⚡ Quick Start — If You Read Nothing Else

The 8 most important things to know right now.

Most thyroid cancers are highly curable. Papillary thyroid cancer — the most common type (80–85% of cases) — has a 10-year survival rate above 98% when appropriately treated. Even many patients with regional lymph node spread do very well. This is genuinely one of the most treatable cancers.
Not all thyroid nodules need surgery. The majority of thyroid nodules are benign. Fine-needle aspiration (FNA) biopsy and molecular tests like Afirma and ThyroSeq can now determine with high confidence whether a nodule is low-risk, potentially sparing you an unnecessary operation.
Active surveillance is a real option for some small cancers. If you have a papillary thyroid microcarcinoma (under 1 cm) without aggressive features, watching it with regular ultrasound may be just as safe as immediate surgery — with 30 years of follow-up data from Japan supporting this approach.
Molecular testing has changed everything. Knowing whether your cancer carries a BRAF, RET, NTRK, or RAS mutation now directly influences treatment decisions — from surgery extent to whether highly effective targeted therapies are available for you.
There are four major types — and they behave very differently. Papillary and follicular (together called "differentiated") are the most common and most curable. Medullary thyroid cancer (MTC) arises from different cells and requires different monitoring. Anaplastic thyroid cancer (ATC) is rare but aggressive and now has targeted therapy options that didn't exist five years ago.
After thyroidectomy, you will need thyroid hormone for life. Levothyroxine replaces what your thyroid used to make. The dose is carefully managed — in many patients it is intentionally set higher than normal to suppress TSH and reduce recurrence risk. Getting this balance right matters.
Targeted therapies have transformed advanced disease. RET inhibitors (selpercatinib, pralsetinib) achieve response rates above 80% in RET-altered cancers. Lenvatinib nearly triples progression-free survival in RAI-refractory disease. Even anaplastic thyroid cancer with BRAF V600E mutations now responds to dabrafenib plus trametinib.
The overdiagnosis problem is real — and worth understanding. Thyroid cancer incidence has increased dramatically worldwide (up to 15-fold in South Korea), driven largely by detecting small, slow-growing tumors that might never cause harm. Understanding this helps you and your doctor calibrate how aggressive your treatment needs to be.

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Overview — Understanding Thyroid Cancer in 2026

Thyroid cancer occupies a unique position in oncology. It is the most rapidly increasing cancer diagnosis globally, yet the vast majority of cases are highly curable. This apparent contradiction has a straightforward explanation: improved imaging (particularly neck ultrasound) now detects tiny cancers that were always there but previously went unnoticed. Most of these small papillary thyroid cancers grow so slowly that many would never cause symptoms in a lifetime.

That does not mean thyroid cancer is trivial. A subset of thyroid cancers are aggressive, can spread to lymph nodes and distant organs, and require intensive, sophisticated treatment. The art of modern thyroid cancer care is matching treatment intensity to disease risk — avoiding both overtreatment of indolent disease and undertreatment of dangerous disease.

The four major types. Thyroid cancer is not one disease. Papillary (80–85%) and follicular (10–15%) together form "differentiated thyroid cancer" (DTC) — they arise from thyroid follicular cells, usually take up iodine, and respond to radioactive iodine therapy. Medullary thyroid cancer (MTC, 3–5%) arises from C cells that produce calcitonin — it does not respond to RAI and requires different monitoring. Anaplastic thyroid cancer (ATC, 1–2%) is one of the most aggressive human cancers, but BRAF-targeted therapy has begun to change outcomes.

What has changed recently

Molecular testing is now central to care. Tests like Afirma GSC and ThyroSeq v3 can help determine whether an indeterminate thyroid nodule needs surgery, and tumor molecular profiling (BRAF, RET, NTRK, RAS) guides therapy selection in advanced disease.
Active surveillance has been validated. The Kuma Hospital program in Japan has followed over 5,600 patients with small papillary microcarcinomas for up to 30 years. Only 3.8% showed tumor enlargement, and there have been zero thyroid cancer deaths in the surveillance group. This is now a recognized alternative to surgery for carefully selected patients.
Precision-targeted therapies have arrived. Selpercatinib and pralsetinib for RET-altered cancers, dabrafenib plus trametinib for BRAF V600E-mutant ATC, larotrectinib and entrectinib for NTRK-fusion cancers — these represent genuine breakthroughs for patients whose disease once had limited options.
Treatment de-escalation is gaining traction. Guidelines increasingly support less extensive surgery (lobectomy instead of total thyroidectomy) and less radioactive iodine for low-risk patients, recognizing that more aggressive treatment doesn't improve outcomes but does increase complications.

This is a legitimate and important question. Studies from South Korea, where widespread screening programs led to a 15-fold increase in thyroid cancer diagnoses between 1993 and 2011, showed no decrease in thyroid cancer mortality — strong evidence that the additional cancers detected were mostly indolent. Similar patterns have been observed in Italy, France, and the United States.

This does not mean your diagnosis is unimportant. It means that the intensity of your treatment should be calibrated to your specific cancer's biology: its size, location, molecular profile, presence or absence of lymph node involvement, and pathologic features. A 7 mm intrathyroidal papillary cancer without aggressive histologic variants or BRAF V600E mutation is a fundamentally different disease from a 4 cm papillary cancer with extrathyroidal extension and lateral neck lymph nodes.

Ask your team specifically about your risk stratification and what evidence supports the treatment intensity being recommended.

What type of thyroid cancer do I have, and what is my risk category (low, intermediate, or high)?
Has molecular testing been done on my biopsy or surgical specimen? What mutations or fusions were found?
Am I a candidate for active surveillance, or do I definitely need surgery?
If surgery is recommended, do I need a lobectomy or total thyroidectomy? What is the evidence for each in my case?
Will I need radioactive iodine after surgery? Why or why not?
What is my expected long-term prognosis?

If you are supporting someone through a thyroid cancer diagnosis, some things that help early on:

The word "cancer" hits hard regardless of prognosis. Even though most thyroid cancers are curable, hearing "you have cancer" is frightening. Don't minimize the diagnosis, but also don't catastrophize. Help your loved one understand their specific situation.
Attend the surgical consultation together. Surgery decisions (lobectomy vs. total thyroidectomy, central neck dissection) have lifelong implications. Two sets of ears help, especially when nerves are high.
Expect a long follow-up journey. Unlike many cancers where treatment is intensive and then stops, thyroid cancer follow-up often continues for years or decades with blood tests, ultrasounds, and dose adjustments. This marathon pace requires patience.
Help track medications and labs. After thyroidectomy, levothyroxine doses and TSH levels need regular monitoring. Helping keep a log of labs and medication changes is practical and valuable.

Diagnosis & Molecular Testing

The path to a thyroid cancer diagnosis typically begins with a nodule — a lump in the thyroid gland found during a physical exam, incidentally on imaging done for another reason, or noticed by the patient. Most thyroid nodules are benign (95% or more), so the central diagnostic challenge is figuring out which ones need treatment.

The Bethesda system — your biopsy result explained

Fine-needle aspiration (FNA) biopsy is the cornerstone of thyroid nodule evaluation. Results are reported using the Bethesda System for Reporting Thyroid Cytopathology, with six categories:

Bethesda Classification

Bethesda I — Nondiagnostic: Not enough cells to evaluate. Usually requires a repeat FNA. Malignancy risk: 5–10%.
Bethesda II — Benign: No evidence of cancer. Follow-up with ultrasound, no surgery needed in most cases. Malignancy risk: 0–3%.
Bethesda III — Atypia of Undetermined Significance (AUS): Some abnormal cells but not clearly cancerous. This is where molecular testing is most valuable. Malignancy risk: 6–18% (before molecular testing).
Bethesda IV — Follicular Neoplasm: Cannot distinguish benign follicular adenoma from follicular carcinoma on cytology alone. Molecular testing or diagnostic surgery usually recommended. Malignancy risk: 10–40%.
Bethesda V — Suspicious for Malignancy: Likely cancer but not definitive. Surgery usually recommended. Malignancy risk: 45–75%.
Bethesda VI — Malignant: Cancer confirmed. Surgery planned. Malignancy risk: 97–99%.

Molecular testing — avoiding unnecessary surgery

For Bethesda III and IV results (the "indeterminate" categories), molecular testing has been transformative. Instead of proceeding directly to diagnostic surgery to find out if a nodule is cancerous, these tests analyze the genetic profile of the biopsy cells:

Afirma Genomic Sequencing Classifier (GSC): A "rule-out" test. A benign Afirma result carries a negative predictive value of 96% for Bethesda III and 95% for Bethesda IV nodules — meaning you can safely avoid surgery. If suspicious, surgery is typically recommended.
ThyroSeq v3: A "rule-in and rule-out" test that sequences 112 genes. Sensitivity of 87.5% with a negative predictive value of 80% for Bethesda IV nodules. It identifies specific mutations (BRAF, RAS, RET, NTRK) that inform both cancer risk and aggressiveness.
ThyGeNEXT/ThyraMIR: A combined approach using mutation analysis plus microRNA expression.

The practical impact: molecular testing has reduced the rate of unnecessary diagnostic surgery for indeterminate nodules by approximately 50%. If your biopsy comes back Bethesda III or IV, ask whether molecular testing has been performed or would be appropriate before proceeding to surgery.

What your molecular profile means

Beyond diagnosis, molecular testing of thyroid cancer tissue identifies mutations that matter for treatment:

BRAF V600E: The most common mutation in papillary thyroid cancer (40–60%). Associated with more aggressive behavior, higher recurrence risk, and lower RAI avidity. In anaplastic thyroid cancer, it opens the door to dabrafenib plus trametinib targeted therapy.
RET fusions (in papillary TC) and RET point mutations (in medullary TC): RET-selective inhibitors (selpercatinib, pralsetinib) are highly effective. All medullary thyroid cancer patients should have RET testing.
NTRK fusions: Rare (approximately 2–5% of papillary TC) but important because larotrectinib and entrectinib show excellent response rates across NTRK-fusion cancers regardless of tumor origin.
RAS mutations (NRAS, HRAS, KRAS): Common in follicular thyroid cancer and follicular variant of papillary TC. Generally associated with lower aggressiveness and higher RAI responsiveness compared to BRAF-mutant tumors.
TERT promoter mutations: When combined with BRAF V600E, associated with significantly worse prognosis. More common in older patients and aggressive histologic variants.

Active surveillance means monitoring a confirmed small papillary thyroid cancer with regular ultrasound instead of proceeding immediately to surgery. This is appropriate when all of the following criteria are met:

Tumor is less than 1 cm (a "microcarcinoma")
Confined within the thyroid (no extrathyroidal extension)
No suspicious lymph nodes on ultrasound
No aggressive histologic variant or high-risk molecular profile (e.g., BRAF V600E alone is not an absolute contraindication, but BRAF + TERT may be)
Not located adjacent to the recurrent laryngeal nerve or trachea
Patient is willing and able to commit to regular follow-up (typically ultrasound every 6 months for the first 2 years, then annually)

The evidence base is strongest from Japan. Kuma Hospital has followed over 5,600 patients for up to 30 years: 3.8% showed tumor enlargement, 1.6% developed new lymph node metastases, and there were zero thyroid cancer deaths in the surveillance cohort. The key finding: patients who eventually needed surgery after a period of active surveillance had outcomes no different from those who had immediate surgery.

Active surveillance programs are now offered at major centers worldwide including Memorial Sloan Kettering, MD Anderson, and Huntsman Cancer Institute. This is not "doing nothing" — it is a structured, evidence-based monitoring program.

What was my Bethesda category? If III or IV, has molecular testing been done?
If molecular testing was done, what specific mutations or fusions were found?
Based on the molecular results, what does this mean for my cancer's likely behavior?
Am I a candidate for active surveillance, or are there features that make surgery the better choice?
If active surveillance is possible, what does the monitoring schedule look like?
Should my family members be screened? (Especially relevant if medullary thyroid cancer is suspected.)
Do I need any additional imaging (CT, PET) before treatment planning?

The waiting is the hardest part. FNA results take days, molecular tests can take 2–3 weeks. This limbo period is emotionally draining. Help by being present, not by Googling worst-case scenarios.
Write down the Bethesda category and any molecular results. These are the essential data points that drive every subsequent decision.
If active surveillance is offered, support the choice. It can feel counterintuitive to "watch" a cancer, but the evidence is strong. If your loved one chooses surveillance over surgery, validate that decision.
If medullary thyroid cancer is diagnosed, the whole family matters. About 25% of MTC is hereditary (MEN2 syndrome), and genetic testing of family members is essential. Help coordinate this.

Surgery, Radioactive Iodine & Targeted Therapy

Treatment for thyroid cancer is highly individualized, guided by cancer type, stage, molecular profile, and risk stratification. The core pillars are surgery, radioactive iodine (for differentiated thyroid cancer), TSH suppression, and — for advanced disease — targeted systemic therapy.

Surgery — the foundation of treatment

Lobectomy vs. total thyroidectomy. One of the most important shifts in thyroid cancer surgery is the recognition that many patients do equally well with removal of only the affected lobe (lobectomy) rather than the entire thyroid (total thyroidectomy). Current ATA guidelines recommend lobectomy may be sufficient for: unifocal tumors 1–4 cm, no extrathyroidal extension, no clinical lymph node involvement, no aggressive histologic variant, and no prior radiation exposure. Total thyroidectomy is preferred for: tumors >4 cm, bilateral disease, extrathyroidal extension, lymph node metastases, known aggressive variants, distant metastases, or when RAI therapy is planned.

Central neck dissection (level VI): Routine prophylactic central neck dissection remains debated. ATA guidelines suggest it should be considered for clinically involved nodes (therapeutic) or advanced primary tumors, but routine prophylactic dissection for small, low-risk cancers has not been shown to improve survival and increases the risk of hypoparathyroidism.
Lateral neck dissection: Performed only when lateral compartment lymph node metastases are confirmed by biopsy. Never done prophylactically.
Surgical complications to understand: Recurrent laryngeal nerve injury (temporary in 5–10%, permanent in 1–2% at experienced centers), hypoparathyroidism (temporary in 10–30% after total thyroidectomy, permanent in 1–4%), bleeding. Surgeon experience and case volume are among the strongest predictors of complication rates.

Radioactive iodine (RAI) therapy

After total thyroidectomy for differentiated thyroid cancer, RAI may be recommended to destroy any remaining thyroid tissue and treat microscopic disease. Whether you need RAI depends on your risk:

Low-risk (ATA): Small (≤4 cm), intrathyroidal, no aggressive features, no vascular invasion, no lymph node involvement. RAI is generally not recommended. Observation with thyroglobulin monitoring is preferred.
Intermediate-risk: Minor extrathyroidal extension, small lymph node metastases, vascular invasion, aggressive histologic variants. RAI is considered and often recommended. Typical activity: 30–100 mCi.
High-risk: Gross extrathyroidal extension, large lymph node metastases, distant metastases, incomplete surgical resection. RAI is recommended. Typical activity: 100–200 mCi.

RAI works best when TSH levels are high (above 30 mU/L), which is achieved either by:

Thyroid hormone withdrawal (THW): Stopping levothyroxine for 3–4 weeks. You will experience hypothyroid symptoms (fatigue, brain fog, cold intolerance, weight gain). This is temporary but can be significant.
Recombinant human TSH (rhTSH / Thyrogen): Two injections over two days, without stopping levothyroxine. Avoids hypothyroid symptoms. Approved for remnant ablation and increasingly used for adjuvant therapy. Not recommended for treatment of known distant metastases (THW preferred).

Low-iodine diet: For 1–2 weeks before RAI, you'll follow a diet restricted in iodine (avoiding seafood, dairy, iodized salt, processed foods with iodine-containing additives). This depletes iodine stores so thyroid tissue takes up the radioactive iodine more effectively.

Radiation safety precautions: After receiving RAI, you'll emit low levels of radiation for several days to weeks. You'll need to limit close contact with others (especially children and pregnant women), sleep separately, use separate utensils, and flush the toilet twice. Your nuclear medicine team will provide specific instructions based on your dose.

Side effects: Most common are neck tenderness, dry mouth (sialoadenitis — drink plenty of fluids and use sour candy to stimulate salivary flow), taste changes, and nausea. Most are temporary. At higher cumulative doses, concerns about secondary malignancies (very low risk) and fertility effects are discussed.

TSH suppression — levothyroxine as therapy

After thyroidectomy, levothyroxine serves a dual purpose: replacing thyroid hormone and suppressing TSH (which can stimulate thyroid cancer growth). Target TSH levels are risk-stratified:

High-risk or active disease: TSH <0.1 mU/L (full suppression)
Intermediate-risk, initial treatment: TSH 0.1–0.5 mU/L
Low-risk with excellent response: TSH 0.5–2.0 mU/L (near-normal)
Long-term with no evidence of disease: TSH in normal range (0.5–2.0 mU/L)

Over-suppression for prolonged periods carries risks: atrial fibrillation (especially in patients over 65), decreased bone density (especially postmenopausal women), anxiety, and insomnia. Dynamic risk stratification allows TSH targets to be relaxed over time as your disease response becomes clear.

Targeted therapy — when cancer is advanced

For patients whose differentiated thyroid cancer no longer responds to RAI, or for medullary and anaplastic thyroid cancers, targeted therapies represent major advances:

Lenvatinib (Lenvima): A multikinase inhibitor. In the SELECT trial, it extended progression-free survival from 3.6 to 18.3 months in RAI-refractory DTC, with an overall response rate of 64.8%. NCCN Category 1 recommendation. Side effects include hypertension, diarrhea, hand-foot syndrome, fatigue, and weight loss.
Sorafenib (Nexavar): Another multikinase inhibitor. The DECISION trial showed PFS of 10.8 vs. 5.8 months in RAI-refractory DTC. Generally used when lenvatinib is not tolerated or available.
Cabozantinib (Cabometyx/Cometriq): Approved for MTC (EXAM trial: PFS 11.2 vs. 4.0 months) and for differentiated thyroid cancer after prior therapy (COSMIC-311: PFS 11.0 months post-lenvatinib/sorafenib).
Selpercatinib (Retevmo): A RET-selective inhibitor. Received FDA full approval for RET-mutant MTC and RET-fusion thyroid cancer. LIBRETTO-001 showed overall response rates exceeding 80% in MTC and over 90% in RET-fusion DTC. LIBRETTO-531 showed 72% reduction in progression risk vs. cabozantinib/vandetanib as first-line MTC therapy. Better tolerated than multikinase inhibitors.
Pralsetinib (Gavreto): Another RET-selective inhibitor. ARROW trial data show similar efficacy in RET-altered thyroid cancers.
Dabrafenib + trametinib: FDA-approved for BRAF V600E-mutant anaplastic thyroid cancer. The ROAR trial showed a 56% response rate in ATC with median overall survival of 15 months — remarkable for a cancer that previously had median survival of 3–5 months.
Larotrectinib and entrectinib: NTRK inhibitors for NTRK-fusion cancers. Larotrectinib showed an 86% response rate in differentiated thyroid cancer; entrectinib 54% with median PFS of 44 months.

Not all differentiated thyroid cancers respond to radioactive iodine. Cancer is considered "RAI-refractory" when:

The tumor does not take up RAI on a post-therapy scan
The cancer progresses despite adequate RAI treatment
Cumulative RAI dose has reached 600 mCi with no further benefit
Some metastatic sites take up iodine while others do not (mixed response)

At this point, additional RAI is unlikely to help, and systemic therapy (lenvatinib, sorafenib, or molecularly targeted agents) becomes the mainstay. This transition should be managed by a team experienced in thyroid cancer, ideally at a high-volume center.

Thyroid cancer often affects younger adults, making fertility a critical concern:

RAI and fertility: RAI can temporarily affect ovarian and testicular function. Women are advised to avoid pregnancy for 6–12 months after RAI. Men may have temporary decreases in sperm count. Sperm banking should be discussed before high-dose or repeated RAI treatments.
Thyroid cancer during pregnancy: Papillary thyroid cancer discovered during pregnancy can often be monitored safely until after delivery if it is not rapidly growing or involving lymph nodes. Surgery, if needed, is safest in the second trimester. RAI is absolutely contraindicated during pregnancy and breastfeeding.
Levothyroxine in pregnancy: TSH targets change during pregnancy. Dose typically needs to increase by 25–50%. Close monitoring every 4 weeks during the first half of pregnancy is essential.
Targeted therapies and pregnancy: All TKIs and targeted agents are contraindicated in pregnancy. Effective contraception is mandatory during treatment.

Do I need a lobectomy or total thyroidectomy? What is the specific evidence supporting your recommendation?
How many thyroid surgeries does this surgeon perform per year? (High-volume surgeons have lower complication rates.)
Based on my pathology and risk level, do I need radioactive iodine? If so, what dose?
Should I use thyroid hormone withdrawal or Thyrogen injections for RAI preparation?
What is my TSH target, and how long will it need to stay suppressed?
If my cancer comes back or doesn't respond to RAI, what systemic therapy options are available based on my molecular profile?
I am planning to have children — how does this affect my treatment timeline?

Post-surgical recovery is usually quick. Most patients go home the same day or the next day after thyroid surgery. Monitor for signs of low calcium (tingling around the mouth, fingertips, muscle cramps) — this indicates hypoparathyroidism and needs medical attention.
RAI isolation can be lonely. Your loved one will need to stay physically distant for several days after radioactive iodine. Prepare separate sleeping arrangements, separate bathroom supplies, and a plan for meals and emotional support from a distance.
Hypothyroid preparation periods are miserable. If thyroid hormone withdrawal is used before RAI, expect significant fatigue, cognitive slowing, and mood changes. Be patient, practical, and don't expect productivity during this time.
Medication management is ongoing. Levothyroxine should be taken at the same time daily, on an empty stomach, 30–60 minutes before food or other medications. Help establish this routine.

Monitoring & Survivorship

One of the defining features of thyroid cancer care is the extended monitoring period. Unlike many cancers where surveillance tapers after five years, thyroid cancer follow-up often continues for decades — because recurrences can occur late, and because thyroid hormone management is lifelong.

Dynamic risk stratification — your risk changes over time

A crucial concept in modern thyroid cancer care: your initial risk category (determined at diagnosis and surgery) is not fixed. It is updated based on your response to treatment. The ATA defines four response categories:

Response to Therapy Categories

Excellent response: Thyroglobulin <0.2 ng/mL (suppressed) or <1 ng/mL (stimulated), negative thyroglobulin antibodies, negative neck ultrasound, negative RAI scan (if done). Recurrence risk drops to 1–4% regardless of initial risk category.
Biochemical incomplete: Elevated thyroglobulin or rising thyroglobulin antibodies without structural disease on imaging. 15–20% will eventually have identifiable structural disease.
Structural incomplete: Persistent or newly identified disease on imaging. Requires further treatment consideration.
Indeterminate: Nonspecific findings that can't be confidently classified. Usually observed with continued monitoring.

This dynamic approach means that a patient initially classified as intermediate-risk who achieves an excellent response can have their TSH target relaxed and monitoring intervals extended — acknowledging that the cancer is behaving like low-risk disease.

Thyroglobulin — your key blood marker

After total thyroidectomy and RAI, thyroglobulin (Tg) is the most important tumor marker for differentiated thyroid cancer. Any thyroglobulin remaining after complete treatment suggests residual thyroid tissue — either normal remnant or cancer.

What's normal: After successful treatment, suppressed Tg should be undetectable (<0.2 ng/mL). Stimulated Tg (after TSH elevation or Thyrogen) should be <1 ng/mL.
Thyroglobulin antibodies (TgAb): Present in 20–25% of thyroid cancer patients. When present, they can falsely lower Tg levels (immunometric assays) or falsely elevate them (RIA). TgAb trends become the proxy marker — declining TgAb is reassuring; rising TgAb is concerning.
Rising Tg or TgAb: Triggers additional imaging — usually neck ultrasound first, then potentially CT, RAI diagnostic scan, or FDG-PET/CT depending on the clinical picture.

Monitoring schedule

First 1–2 years: Physical exam, TSH, Tg, TgAb every 3–6 months. Neck ultrasound at 6–12 months post-surgery, then every 6–12 months.
Years 2–5 (excellent response): Labs every 6–12 months. Neck ultrasound annually or as clinically indicated.
After 5 years (excellent response): Labs annually. Ultrasound can be spaced to every 2–3 years or discontinued if low-risk with sustained excellent response.
Lobectomy patients: Thyroglobulin interpretation is different (normal remaining thyroid produces Tg). Ultrasound of the remaining lobe and thyroid bed is the primary monitoring tool.

Living well with thyroid cancer

Take on an empty stomach, at least 30–60 minutes before eating or drinking anything other than water.
Separate from calcium supplements, iron supplements, and antacids by at least 4 hours (they impair absorption).
Coffee can reduce absorption — take levothyroxine at least 30 minutes before coffee, or consider the liquid or gel cap formulation which is less affected.
Maintain consistency — same time each day, same brand if possible (different generics can have slightly different bioavailability).
If you miss a dose, take it as soon as you remember. If close to the next dose, you can double up once without concern.
Pregnancy, significant weight changes, GI conditions, and new medications may all require dose adjustment. Notify your doctor.

Thyroid cancer patients often face a paradox: the cancer is "the good cancer" in the eyes of others, but the experience of diagnosis, surgery, RAI, and lifelong follow-up can cause significant anxiety, depression, and fear of recurrence. Studies show that thyroid cancer survivors report quality-of-life impacts comparable to those with cancers considered much more serious.

Cancer-related anxiety is real and valid. Regular scans and blood tests can trigger "scanxiety." Acknowledge this to yourself and your care team.
Hypothyroid symptoms affect mood. Even with "normal" lab values, some patients continue to experience fatigue, brain fog, mood changes, and weight fluctuations. Work with your endocrinologist on optimizing not just TSH but free T3 and free T4 levels.
Body image and voice changes. A neck scar, voice changes after surgery, and thyroid hormone-related weight fluctuations can all affect self-image. These concerns are legitimate and deserve attention.
Connect with others. ThyCa: Thyroid Cancer Survivors' Association (thyca.org), the American Thyroid Association patient resources, and local support groups can help you feel less alone.

What is my current response category (excellent, biochemical incomplete, structural incomplete, or indeterminate)?
Can we relax my TSH target based on my response to treatment?
My thyroglobulin is [value] — what does that mean for me specifically?
I have thyroglobulin antibodies — how does that affect monitoring?
How often do I need ultrasound and blood work at this point?
I'm still experiencing fatigue / brain fog / weight issues despite "normal" labs. What can we try?
At what point can we consider me in long-term remission?

Don't minimize the "good cancer" experience. Comments like "at least you had the good kind" are well-intentioned but invalidating. Your loved one is dealing with a cancer diagnosis, surgery, lifelong medication, and ongoing surveillance. Treat it as serious as it feels to them.
Help with appointment scheduling. The monitoring schedule is frequent early on and can feel overwhelming. Help keep a calendar of labs, ultrasounds, and specialist visits.
Watch for signs of depression. The combination of hypothyroid symptoms, scanxiety, and the post-treatment emotional drop can lead to clinical depression. Encourage professional support if you notice persistent withdrawal, hopelessness, or loss of interest.
Celebrate milestones. Each clean scan, each drop in thyroglobulin, each year without recurrence is worth acknowledging.

If radioactive iodine therapy is recommended, a low-iodine diet (LID) for 1–2 weeks beforehand maximizes the amount of RAI your thyroid tissue absorbs. This makes the treatment more effective.

What to avoid on LID (2 weeks before RAI):

Iodized salt and sea salt — use non-iodized kosher salt or sea salt labeled "non-iodized"
Seafood of all kinds — fish, shellfish, seaweed, sushi
Dairy products — milk, cheese, yogurt, butter, ice cream
Egg yolks (egg whites are allowed)
Commercial bread and most cereals (many contain iodine from dough conditioners or enriched flour)
Red dye #3 (FD&C Red No. 3) — found in some foods and medications
Multivitamins or supplements containing iodine — hold these for 2 weeks; discuss with your doctor
Amiodarone (heart medication) — contains large amounts of iodine; discuss with your cardiologist before holding

What IS allowed:

Fresh meat, chicken, turkey (not canned)
Fresh fruits and most vegetables
Oatmeal, rice, plain pasta, non-enriched grains
Egg whites, most nuts and seeds
Black coffee, tea without milk, most fruit juices

The TSH boost — two options:

Thyrogen (rhTSH) injections: Two injections over 2 days while you stay on your levothyroxine. You feel normal throughout. This is the standard and preferred approach for most patients.
Thyroid hormone withdrawal (THW): Stop levothyroxine 4–6 weeks before RAI, allowing TSH to rise naturally. You will experience significant hypothyroid symptoms (fatigue, brain fog, cold intolerance, mood changes). This is generally used only when maximum TSH elevation is needed for therapeutic RAI dosing.

After RAI — radiation precautions:

Avoid close contact with pregnant women and children under 12 for 3–7 days (your doctor will give specific guidance based on dose)
Sleep alone for a few nights
Use separate utensils/dishes for a few days; flush twice after using the toilet
ThyCa (thyca.org) has a free Low-Iodine Cookbook with meal plans and recipes specifically designed for this period

Many thyroid cancer survivors experience fatigue, brain fog, weight changes, or mood issues even when their TSH is "within the normal range." This is one of the most common quality-of-life concerns after thyroid cancer treatment — and it deserves a real conversation with your endocrinologist.

TSH is not the whole picture. TSH is the pituitary signal telling the thyroid to produce hormone. Free T4 (the storage hormone) and free T3 (the active hormone that cells actually use) give additional information about how your body is actually using thyroid hormone. Some patients feel better when free T3 is in the upper half of the normal range.
The T3 discussion. Some patients feel better with a small amount of liothyronine (T3) added to their levothyroxine (T4). A small but growing body of evidence supports a combination approach in selected patients. This is not right for everyone, and TSH must be carefully monitored to avoid over-treatment. Ask your endocrinologist about combination T4/T3 therapy if you continue to have symptoms despite optimized T4 dosing.
TSH suppression side effects. If your cancer is intermediate or high risk, your doctor may keep your TSH lower than normal to suppress stimulation of any residual cancer cells. This "subclinical hyperthyroid" state can cause palpitations, mild anxiety, insomnia, and over time increases atrial fibrillation risk and contributes to bone loss. As your risk reclassification improves, advocate for relaxing TSH to a more physiologic range. Your doctor can guide when this is safe based on your response to treatment.
Timing and consistency matter. Levothyroxine absorption varies significantly based on timing, food, and other medications. If your labs fluctuate or you feel inconsistent, review your dosing habits. Taking the medication at the same time each day, 30–60 minutes before eating or drinking anything other than water, improves absorption stability.
Questions to ask your endocrinologist:
- Can you check my free T3 and free T4 in addition to TSH?
- Am I a candidate for T3/T4 combination therapy?
- Can we try relaxing my TSH target given my current response category?
- Is my continued fatigue/brain fog related to thyroid hormone levels, or could something else be contributing?

Advanced Disease & Clinical Trials

While most thyroid cancer patients have excellent outcomes with surgery and RAI, a subset will develop advanced, progressive, or refractory disease that requires systemic therapy. This section covers the latest treatment approaches and emerging options.

Treatment sequencing for RAI-refractory differentiated thyroid cancer

When differentiated thyroid cancer no longer responds to radioactive iodine and is progressing, systemic therapy is considered. Important principles:

Not all RAI-refractory disease needs immediate treatment. Slowly growing, asymptomatic disease may be safely observed. The decision to start systemic therapy considers rate of progression, tumor burden, symptoms, and patient preference.
Molecular profiling guides therapy selection. Before starting any systemic agent, ensure comprehensive molecular testing has been done. RET fusions, NTRK fusions, and specific BRAF mutations may qualify you for highly effective, better-tolerated selective inhibitors rather than broad multikinase inhibitors.
First-line for non-targeted cases: Lenvatinib (preferred based on SELECT trial data showing superior PFS and response rates) or sorafenib.
Second-line: Cabozantinib (COSMIC-311 data) or clinical trial.
Mutation-specific: Selpercatinib or pralsetinib for RET fusions; larotrectinib or entrectinib for NTRK fusions.

Redifferentiation therapy — restoring RAI sensitivity

An exciting frontier: using targeted agents to make RAI-refractory tumors take up iodine again. This approach exploits the fact that many "refractory" tumors have suppressed but not entirely lost the ability to concentrate iodine:

Selumetinib (MEK inhibitor): In a key study, 60% of patients with RAI-refractory DTC showed restored RAI uptake after selumetinib treatment, and some achieved partial responses with subsequent RAI. However, the larger phase 3 ASTRA trial did not meet its primary endpoint, tempering initial enthusiasm.
Other approaches under investigation: Dabrafenib (for BRAF-mutant tumors), trametinib, and combination strategies are being studied for redifferentiation potential.

Immunotherapy in thyroid cancer

Checkpoint inhibitors are being studied in thyroid cancer, particularly in combination with TKIs:

Pembrolizumab + lenvatinib: Phase 2 data show a 65.5% overall response rate in RAI-refractory DTC and 52% in ATC. Studies are ongoing.
Nivolumab and ipilimumab combinations: Being evaluated in ATC and advanced MTC in clinical trials.
Note: Single-agent immunotherapy has shown limited activity in thyroid cancer. The combination approach appears more promising.

Next-generation targeted agents

Next-gen RET inhibitors: LOXO-260, enbezotinib (EP0031), SY-5007, and TY-1091 are in development to overcome resistance mutations (particularly the solvent front G623R mutation) that can develop during treatment with selpercatinib or pralsetinib.
Neoadjuvant targeted therapy: Using dabrafenib/trametinib or selpercatinib before surgery to shrink locally advanced tumors is being studied in clinical trials (including NCT04675710 for BRAF-mutant ATC).

Key clinical trials — past and ongoing

The following trials have shaped or are actively shaping thyroid cancer treatment. Knowing their names and identifiers helps you discuss options with your oncologist and search for enrollment opportunities.

SELECT (NCT01321554) — The landmark trial that led to lenvatinib approval for RAI-refractory DTC. Showed PFS of 18.3 vs 3.6 months.
DECISION (NCT00984282) — Led to sorafenib approval for RAI-refractory DTC. PFS 10.8 vs 5.8 months.
COSMIC-311 (NCT03690388) — Established cabozantinib as a second-line option for RAI-refractory DTC after prior TKI therapy.
LIBRETTO-001 (NCT03157128) — The pivotal basket trial for selpercatinib in RET-altered cancers. Response rates above 80% in MTC and above 90% in RET-fusion DTC.
LIBRETTO-531 (NCT04211337) — Head-to-head comparison of selpercatinib vs cabozantinib/vandetanib as first-line MTC therapy. Showed 72% reduction in progression risk.
ARROW (NCT03037385) — Pivotal trial for pralsetinib in RET-altered thyroid cancer.
ROAR (NCT02034110) — Demonstrated dabrafenib + trametinib efficacy in BRAF V600E-mutant ATC (56% response rate).
ASTRA (NCT01843062) — Phase 3 trial of selumetinib + RAI for RAI-refractory DTC. Did not meet its primary endpoint.
ESTIMABL2 (NCT01837745) — French trial showing that omitting RAI was non-inferior to low-dose RAI for low-risk DTC. Changed practice in Europe and influenced US guidelines.
NCT04675710 — Ongoing trial evaluating neoadjuvant dabrafenib/trametinib before surgery for BRAF V600E-mutant ATC.

Finding and joining clinical trials

Where to search for thyroid cancer clinical trials:

ClinicalTrials.gov — search "thyroid cancer" filtered by your cancer type and location
American Thyroid Association clinical trials page
NCCN clinical trial resources
Huntsman Cancer Institute (Utah) clinical trials office: healthcare.utah.edu/huntsmancancerinstitute/clinical-trials. Phone: 801-585-0303
Ask your oncologist about trials at MD Anderson, Memorial Sloan Kettering, and other NCI-designated cancer centers

Multikinase inhibitors and targeted agents have significant side effects that require proactive management. Knowing what to watch for helps you stay on therapy longer and at effective doses:

Hypertension (lenvatinib, cabozantinib): Very common (up to 70% with lenvatinib). Requires blood pressure monitoring at home and often one or more antihypertensive medications. Uncontrolled hypertension can be dangerous.
Hand-foot syndrome (sorafenib, lenvatinib, cabozantinib): Painful redness, swelling, and peeling on palms and soles. Moisturize aggressively, wear comfortable shoes, report early symptoms for dose adjustment.
Diarrhea: Common with most TKIs. Loperamide and dietary modifications help. Report persistent diarrhea — dehydration can be serious.
Hepatotoxicity: Liver function must be monitored regularly. Report jaundice, dark urine, or right upper abdominal pain immediately.
Fistula risk (particularly with cabozantinib): Rare but serious. Increased risk in patients with tumors involving the aerodigestive tract. Report any new or worsening cough with eating, or any unusual wound.
Fatigue and weight loss: Nearly universal. Nutritional support and activity as tolerated are important.

Has comprehensive molecular profiling been done on my tumor? Are there targetable mutations?
Is my disease truly RAI-refractory, or would a redifferentiation approach be worth trying?
What is the rate of progression, and does it warrant starting systemic therapy now, or can we continue watching?
Given my molecular profile, is there a clinical trial I should consider?
What are the realistic goals of systemic therapy — cure, long-term control, or symptom management?
How will side effects be monitored and managed? Do you have experience managing TKI toxicities?
Should I be seen at a high-volume thyroid cancer center for a second opinion?

This is a different phase — adjust expectations. When thyroid cancer becomes advanced, the treatment landscape shifts from curative to managing a chronic, serious illness. This is an emotional turning point for both patient and family.
Help with medication management. Targeted therapy drugs have specific timing, food requirements, and interaction profiles. Pillboxes, medication apps, and a written schedule help.
Monitor blood pressure. If your loved one is on lenvatinib or cabozantinib, home blood pressure monitoring (twice daily) is essential. Help track and report readings.
Advocate for clinical trials. If you are near a major cancer center, help explore trial options. Sometimes patients need a push to consider this path.
Take care of yourself. Advanced cancer caregiving is exhausting. Use available support resources and don't neglect your own health.

Starting lenvatinib, cabozantinib, selpercatinib, or another targeted therapy is a significant transition. Knowing what to expect — practically and emotionally — helps you stay on therapy longer and at effective doses.

Blood pressure monitoring is non-negotiable on lenvatinib or cabozantinib. These drugs cause hypertension in 60–70% of patients. You will need a home blood pressure cuff. Check and log your BP twice daily for the first month. Your oncology team will give you parameters for when to call vs. take extra BP medication vs. go to urgent care. Do not skip this step — uncontrolled high BP is one of the most common reasons for dose reductions or hospitalization on these drugs.
Start foot and hand care on Day 1, before symptoms appear. Hand-foot syndrome (painful redness and peeling on palms/soles) is common and largely preventable with aggressive early moisturizing. Start urea cream (20% or 40%) on hands and feet daily before treatment begins. Wear comfortable, well-fitting shoes with good cushioning. Avoid prolonged walking on hard floors, high heels, or activities that create pressure on your feet. If you notice redness, tingling, or tenderness starting on your palms or soles, call your oncology team immediately — early intervention prevents dose-limiting Grade 2–3 toxicity.
Fatigue and appetite loss are nearly universal. Build rest into your schedule — especially the first 4–8 weeks as your body adjusts. Eat small, frequent meals and focus on protein and calorie density. Some patients lose significant weight on these drugs; bring someone with you to appointments to help track changes you may not notice yourself.
Diarrhea is common and manageable. Have loperamide (Imodium) at home from day 1. Contact your team after 3–4 loose stools in a day, or sooner if you feel dehydrated (dizziness, very dark urine, not urinating). Staying hydrated is as important on TKIs as the drug itself.
Selpercatinib (Retevmo) is substantially better tolerated than the broad multikinase inhibitors above. If you have a RET fusion or RET mutation, this is one of the main benefits of precision therapy: similar or better efficacy with a much more manageable side-effect profile. The most common side effects are dry mouth, constipation, elevated blood pressure, and elevated liver enzymes. Most patients describe selpercatinib as much more livable than lenvatinib.
Dose reductions are not failures. Clinical trials show that most patients need at least one dose reduction; this is built into the treatment plan. A dose reduction that keeps you on therapy for 18 months is far better than staying at full dose for 3 months and stopping. Report side effects early so your team can manage them proactively.
Patient support resources: The Light of Life Foundation (lightoflifefoundation.org) and ThyCa (thyca.org) both have resources specifically for patients on systemic therapy. Your pharmaceutical company's patient support program (e.g., Eisai's Engage patient support for Lenvima, Lilly's RETSearch for Retevmo) offers nursing support, financial assistance, and practical guidance.

If your thyroid cancer has been identified as RET-positive — either a RET fusion (in differentiated or papillary thyroid cancer) or a RET mutation (in medullary thyroid cancer) — you qualify for selpercatinib (Retevmo), a drug designed specifically to block the RET protein. Understanding what this means can help you ask the right questions and know what to expect.

What "RET fusion" means in plain language. Every cancer cell has DNA. In RET fusion-positive papillary thyroid cancer, a piece of the RET gene has accidentally joined with another gene (most commonly CCDC6 or NCOA4). This fusion creates an abnormal RET protein that is permanently "on," constantly signaling cells to grow and divide. Selpercatinib is specifically designed to block this signal. Because it targets only RET — and not dozens of other proteins like lenvatinib does — selpercatinib causes fewer off-target side effects.
What the clinical trial results showed. In the LIBRETTO-001 trial (the study that led to FDA approval), selpercatinib produced a response rate of greater than 90% in patients with RET fusion-positive differentiated thyroid cancer — meaning the cancer shrank significantly in over 9 out of 10 patients. In medullary thyroid cancer, the LIBRETTO-531 trial showed selpercatinib reduced the risk of disease progression by 72% compared to cabozantinib or vandetanib. These are some of the best results seen in advanced thyroid cancer.
What happened to pralsetinib (Gavreto)? Pralsetinib is a similar RET inhibitor that was FDA-approved in 2020 but was voluntarily withdrawn from the US market by Genentech/Roche in 2024 for commercial reasons (not because of safety or effectiveness problems). If you were on pralsetinib, you were transitioned to selpercatinib or a clinical trial. Pralsetinib is still available in Canada and some other countries.
Asking about molecular testing. If you have advanced thyroid cancer and have NOT had comprehensive molecular testing, ask your oncologist: "Have I been tested for RET fusions or mutations? If not, can we test a tumor sample?" This is especially important if you have MTC (where RET mutations are very common) or if you have papillary thyroid cancer with a history of prior neck radiation or young age at diagnosis (where RET fusions are more common).
Next-generation RET inhibitors. Resistance to selpercatinib can develop over time. Several next-generation RET inhibitors (LOXO-260, enbezotinib, others) are being evaluated in clinical trials for patients who develop resistance. If you progress on selpercatinib, ask about trial eligibility at an academic center.

International Access & Regulatory Landscape

Thyroid cancer treatment is broadly similar worldwide for standard therapies (surgery, RAI, levothyroxine suppression), but access to newer targeted agents, molecular testing platforms, and clinical trial participation varies significantly by region. Patients traveling internationally or comparing treatment options should be aware of these differences.

Sorafenib (Nexavar): FDA-approved 2013 for locally recurrent or metastatic, progressive, RAI-refractory DTC
Lenvatinib (Lenvima): FDA-approved 2015 for RAI-refractory DTC
Vandetanib (Caprelsa): FDA-approved 2011 for symptomatic or progressive medullary thyroid cancer (MTC). Restricted distribution through REMS program due to QTc prolongation risk
Cabozantinib (Cabometyx/Cometriq): FDA-approved 2012 for progressive MTC (Cometriq) and 2021 for RAI-refractory DTC after prior TKI (Cabometyx, based on COSMIC-311)
Selpercatinib (Retevmo): FDA-approved for RET-mutant MTC (age ≥12, prior treatment required initially; first-line approval 2023 based on LIBRETTO-531) and RET-fusion thyroid cancer
Pralsetinib (Gavreto): FDA-approved 2020 for RET-mutant MTC and RET-fusion thyroid cancer. Note: pralsetinib was voluntarily withdrawn from the US market by Genentech in 2024 for commercial reasons, not safety concerns. It remains available in some other countries
Larotrectinib (Vitrakvi) and entrectinib (Rozlytrek): FDA-approved tissue-agnostic for NTRK-fusion cancers, including thyroid cancer
Dabrafenib + trametinib: FDA-approved 2018 for BRAF V600E-positive ATC with no satisfactory locoregional alternatives (based on ROAR trial)
Molecular testing: Afirma GSC and ThyroSeq v3 widely available through commercial labs. Next-generation sequencing panels (FoundationOne, Tempus) routinely used for advanced disease

Lenvatinib and sorafenib: EMA-approved for RAI-refractory DTC. NICE recommends lenvatinib through the Cancer Drugs Fund and sorafenib for DTC
Vandetanib and cabozantinib: EMA-approved for MTC. Access varies by country through national reimbursement decisions
Selpercatinib: EMA-approved 2021 for RET-altered thyroid cancer. NICE approved via the Cancer Drugs Fund. Availability subject to national pricing agreements
Pralsetinib: EMA marketing authorization application was withdrawn by Roche in 2022; not available in the EU
Dabrafenib + trametinib for ATC: Accessible through national compassionate use programs in many EU member states. Not universally reimbursed for this indication
ESMO guidelines: Generally more conservative with RAI use in low-risk DTC compared to US practice. The ESTIMABL2 trial (conducted in France) supports omitting RAI in low-risk patients
Active surveillance: Less uniformly adopted in Europe compared to Japan and increasingly the US, though ESMO 2024 guidelines include it as an option for papillary microcarcinomas

Pioneer of active surveillance: Japan has the longest experience with active surveillance for papillary thyroid microcarcinoma (<1 cm). Landmark studies from Kuma Hospital and Cancer Institute Hospital in Tokyo demonstrated that most PTMCs do not grow over 10+ years of follow-up, leading to worldwide adoption of this approach
Lenvatinib: Developed by Eisai (Japanese company). PMDA-approved for thyroid cancer. The SELECT trial was partly designed and conducted in Japan
Vandetanib and cabozantinib: PMDA-approved for MTC
Selpercatinib: PMDA-approved for RET-altered thyroid cancer
JTA (Japan Thyroid Association) guidelines: More conservative surgical approach overall; stronger endorsement of lobectomy for small, low-risk cancers. Japanese guidelines have historically differed from ATA guidelines on extent of surgery and RAI use

Lenvatinib and sorafenib: Health Canada-approved for RAI-refractory DTC. Provincial formulary coverage varies
Cabozantinib: Approved for MTC and DTC after prior VEGFR-targeted therapy
Selpercatinib: Health Canada-approved for RET-mutant MTC and RET-fusion thyroid cancer. Provincial reimbursement through pan-Canadian Pharmaceutical Alliance negotiation
Pralsetinib: Health Canada-approved (still available in Canada as of 2025, unlike the US where it was withdrawn)
Key Canadian resources: Canadian Cancer Trials Group (CCTG) runs thyroid cancer-relevant studies. Thyroid Cancer Canada provides patient support and advocacy

Australia (TGA): Lenvatinib and sorafenib are TGA-approved and listed on the Pharmaceutical Benefits Scheme (PBS) for RAI-refractory DTC. Selpercatinib received TGA approval. The Australian Endocrine Society follows modified ATA guidelines with local adaptations
South Korea: High thyroid cancer incidence rates (historically among the highest globally, partly due to widespread ultrasound screening). Korean Thyroid Association guidelines align with ATA but emphasize screening-related management. Active surveillance adoption is growing
Iodine-deficient regions (parts of sub-Saharan Africa, South/Southeast Asia): Higher proportion of follicular thyroid cancer. More advanced disease at presentation due to limited access to ultrasound and FNA. Targeted therapy access is often unavailable or unaffordable. RAI may be limited to national referral centers

Key takeaway for patients: If you are considering treatment outside your home country, or if you have been told a medication is unavailable in your region, ask your oncologist about compassionate use programs, clinical trial enrollment, and international second opinions. Some centers (e.g., MD Anderson, Memorial Sloan Kettering, Institut Gustave Roussy) accept international patients.

Failed & De-Adopted Therapies

Knowing what has been tried and did not work is just as important as knowing what does work. These are treatments that were once used or studied for thyroid cancer but have been abandoned, proven ineffective, or withdrawn due to safety concerns. If anyone suggests these approaches, you should discuss the evidence with your medical team.

External beam radiation for routine low-risk DTC

DE-ADOPTED

External beam radiation therapy (EBRT) was historically used after surgery for differentiated thyroid cancer even in low-risk patients. Evidence showed no benefit in this setting, with significant toxicity to surrounding neck structures. EBRT is now reserved only for locally advanced, unresectable disease, gross residual disease that does not respond to RAI, or anaplastic thyroid cancer. It is not part of standard management for low-risk DTC.

Routine high-dose RAI for low-risk papillary thyroid cancer

DE-ADOPTED

High-dose radioactive iodine (100–200 mCi) was once given routinely to nearly all thyroid cancer patients after total thyroidectomy. Multiple studies, including the HiLo trial and ESTIMABL1/ESTIMABL2 trials, demonstrated that low-risk DTC patients either need no RAI at all or only low-dose (30 mCi) ablation. High-dose RAI in low-risk patients causes unnecessary radiation exposure without improving outcomes and increases the rare risk of secondary malignancies and salivary gland damage.

Selumetinib (AZD6244) as standalone RAI-refractory DTC treatment

FAILED

Selumetinib, a MEK inhibitor, generated considerable excitement after a 2013 pilot study showed it could restore radioactive iodine uptake in some RAI-refractory patients. However, the larger phase 3 ASTRA trial did not meet its primary endpoint of improved complete remission rate when combined with RAI versus placebo plus RAI. Research into redifferentiation continues with other agents and combination approaches, but selumetinib alone did not deliver the hoped-for results.

Pralsetinib (Gavreto) — US market withdrawal

WITHDRAWN (US)

Pralsetinib was FDA-approved in 2020 for RET-altered thyroid cancer and showed meaningful clinical activity. In 2024, Genentech/Roche voluntarily withdrew it from the US market for commercial reasons (not safety or efficacy concerns). Selpercatinib remains available and demonstrated superior outcomes versus cabozantinib or vandetanib in the head-to-head LIBRETTO-531 trial. Pralsetinib remains available in Canada and some other countries. Patients previously on pralsetinib were transitioned to selpercatinib or clinical trials.

Doxorubicin monotherapy for advanced thyroid cancer

DE-ADOPTED

Before targeted therapies became available, doxorubicin (Adriamycin) was the only FDA-approved chemotherapy for thyroid cancer. Its response rates were poor (10–20% at best), responses were typically short-lived, and toxicity was significant (cardiac toxicity, myelosuppression). It has been largely replaced by multikinase inhibitors and selective targeted agents for advanced DTC and MTC, and by combination regimens for ATC.

Routine total thyroidectomy for all thyroid cancers

DE-ADOPTED

For decades, total thyroidectomy was performed on virtually every thyroid cancer patient regardless of tumor size or risk factors. The ATA 2015 guidelines and subsequent evidence demonstrated that lobectomy (removing only the affected lobe) is appropriate and equally effective for unifocal tumors 1–4 cm without extrathyroidal extension, lymph node involvement, or high-risk features. Lobectomy avoids the need for lifelong thyroid hormone replacement in some patients and eliminates the risk of bilateral recurrent laryngeal nerve injury and permanent hypoparathyroidism associated with total thyroidectomy.

Thyroid hormone suppression to undetectable TSH in all patients

DE-ADOPTED

Aggressive TSH suppression (TSH <0.1 mU/L) was once applied to all thyroid cancer patients indefinitely. Evidence now shows that this degree of suppression benefits only high-risk and intermediate-risk patients. For low-risk patients who achieve excellent response (undetectable thyroglobulin, no structural disease), TSH can be maintained at 0.5–2.0 mU/L, reducing the risks of atrial fibrillation, osteoporosis, and other complications of subclinical hyperthyroidism. Dynamic risk stratification guides individualized TSH targets over time.

Why this matters: Medicine evolves. Treatments once considered standard are regularly re-evaluated as new evidence emerges. If you are receiving any of these older approaches, it does not necessarily mean your care is wrong — individual circumstances may warrant exceptions. But you should discuss the current evidence with your medical team to ensure your treatment plan reflects the latest understanding.

The failed and de-adopted therapies listed in this section have been superseded in most circumstances. If your care team recommends one, the right response is not automatic refusal — there may be individual circumstances where exceptions are appropriate — but to ask questions that help you understand whether current evidence supports the recommendation for your specific situation.

If total thyroidectomy is recommended for a small, low-risk cancer: "My cancer appears to be unifocal and under 4 cm without concerning features. Is lobectomy an option for me? I've read that ATA 2015 guidelines allow lobectomy in this situation. What factors specific to my cancer make you recommend total thyroidectomy?"
If high-dose RAI (100+ mCi) is recommended for a low-risk cancer: "My cancer appears to be low-risk. The ESTIMABL2 trial showed that low-risk DTC patients don't need high-dose RAI. Am I a candidate for low-dose (30 mCi) ablation, or for skipping RAI entirely? What puts me in a higher-risk category that changes this?"
If aggressive TSH suppression (TSH <0.1) is planned long-term for a low-risk cancer in remission: "My current response category is excellent. I've read that long-term aggressive TSH suppression increases risks of heart problems and osteoporosis. Can we discuss relaxing my TSH target to 0.5–2.0 given my low-risk status and excellent response?"
If doxorubicin chemotherapy is offered: "I understand doxorubicin was historically used but has been replaced by targeted therapies for most thyroid cancer types. Can you tell me why doxorubicin specifically is being recommended for my situation? Are there targeted therapy options or clinical trials I should consider first?"
General approach to any unexpected recommendation:
- Ask: "What current guidelines support this approach for my specific type and stage of thyroid cancer?"
- Ask: "What would a major cancer center like Huntsman, MD Anderson, or Memorial Sloan Kettering typically recommend for a patient in my situation?"
- Consider a second opinion at a high-volume thyroid cancer center for any treatment decision that gives you pause
- Resources: ATA patient education at thyroid.org; NCCN Patient Guidelines at nccn.org/patients

The fact that some treatments listed in this section were once standard and are no longer used can feel unsettling. Did patients get harmed by unnecessary treatments? Did doctors "not know what they were doing?" It's worth understanding how this process of change actually works, because it's a sign that medicine is doing exactly what it should.

Medical knowledge evolves through systematic evidence gathering, not sudden reversals. The shift away from routine total thyroidectomy for small cancers, or routine high-dose RAI for low-risk patients, didn't happen overnight. It happened because researchers designed careful clinical trials that measured actual outcomes in thousands of patients over many years. When those trials showed that the older approaches weren't improving survival but were adding harm, guidelines were updated. This is the system working correctly.
Past patients were not mistreated. Doctors treated patients based on the best available evidence at the time. The trials didn't exist yet; the data were not available. Medicine's highest obligation is to follow the evidence as it develops — and that's exactly what happened.
How to evaluate new claims you find online. Medical claims you encounter outside your care team should be evaluated carefully. Ask: (1) Is this from a peer-reviewed journal or a clinical guideline, or from a patient forum, supplement website, or media story? (2) Is this a small pilot study or a large Phase 3 randomized trial? (3) Do major guidelines (ATA, NCCN, ESMO) reflect this recommendation? (4) Has this been replicated independently? A single promising study rarely changes practice — it initiates a larger investigation. Selumetinib's story is the perfect example: exciting pilot data, then a Phase 3 trial that didn't confirm the same results in a broader population.
The takeaway for your care. You can feel confident asking your oncologist about the evidence base for any recommendation. A good oncologist welcomes informed patients and is happy to cite the guideline or trial supporting their recommendation. If they can't or won't — that's a reason to seek a second opinion. Medicine at its best is a partnership between an informed patient and a clinician committed to evidence-based practice.

Support & Resources

Mountain West / Utah

Huntsman Cancer Institute (HCI) Thyroid/Endocrine Cancer Program: Comprehensive, multidisciplinary team including endocrine surgeons, endocrinologists, nuclear medicine specialists, medical oncologists, and genetic counselors. Clinical trials available. Phone: 801-585-0303. healthcare.utah.edu/huntsmancancerinstitute
University of Utah Endocrine Surgery: High-volume thyroid surgery center performing over 300 thyroid operations annually, with complication rates among the best nationally. Active surveillance program available for eligible patients. Phone: 801-581-2121 (U of U Health main).
University of Utah Nuclear Medicine: Full RAI therapy services including pre-treatment dosimetry, post-therapy whole-body scans, and SPECT/CT for localization. Phone: 801-581-2121.
Intermountain Health Endocrinology: Multiple locations across Utah for ongoing thyroid cancer follow-up, levothyroxine management, and referral coordination with HCI for complex cases. Phone: 801-442-2000.
George E. Wahlen VA Medical Center: Endocrinology and oncology services for veterans, including thyroid cancer follow-up and coordination with HCI for specialized care. Phone: 801-582-1565.
University of Utah Genetic Counseling: Genetic testing and counseling for MEN2 syndrome, familial medullary thyroid cancer, and other hereditary thyroid cancer syndromes (Cowden syndrome, FAP-associated thyroid cancer).

How to choose a center. For newly diagnosed low-risk papillary thyroid cancer (small, intrathyroidal, no suspicious lymph nodes), community endocrinology and a high-volume local surgeon may be all you need. Consider referral to an academic center like HCI if: your cancer is medullary or anaplastic, you have been told your disease is RAI-refractory, targeted or systemic therapy is being discussed, you have a hereditary syndrome (MEN2, Cowden), your molecular testing shows an uncommon mutation (NTRK fusion, RET fusion), or you want a second opinion on surgery extent or active surveillance eligibility. Veterans should contact the VA for coordinated referrals to HCI or other NCI-designated centers through the VA Community Care program.

US National

Memorial Sloan Kettering Cancer Center (MSK) Thyroid Cancer Program: One of the highest-volume thyroid cancer programs in the US. Active surveillance program for PTMC. Molecular profiling and clinical trials. mskcc.org
MD Anderson Cancer Center Thyroid Cancer Program: Multidisciplinary endocrine oncology, clinical trials portfolio, and expertise in advanced and refractory disease. mdanderson.org
Mayo Clinic Thyroid Cancer Program: Comprehensive thyroid cancer care across Rochester, Phoenix, and Jacksonville campuses. Expertise in complex surgical cases and RAI dosimetry. mayoclinic.org
Massachusetts General Hospital Thyroid Unit: Longstanding expertise in thyroid cancer management, molecular testing, and clinical trials.

Veterans

George E. Wahlen VA Medical Center (Salt Lake City): Endocrinology, oncology, and nuclear medicine for thyroid cancer. Coordinates with HCI for complex cases. Phone: 801-582-1565.
VA Community Care Program: Veterans may be eligible for referral to NCI-designated cancer centers (including HCI, MSK, MD Anderson) when specialized thyroid cancer expertise is needed beyond what is available at the local VA.
VA National Oncology Program: Provides clinical pathway guidance for thyroid cancer and facilitates tumor board consultation across VA medical centers.

Canada

Princess Margaret Cancer Centre (Toronto): Canada's largest thyroid cancer referral center. Expertise in RAI-refractory disease, targeted therapy, and clinical trial access. Part of University Health Network.
Sunnybrook Health Sciences Centre (Toronto): Odette Cancer Centre thyroid cancer program with endocrine surgery and nuclear medicine expertise.
McGill University Health Centre (Montreal): Thyroid cancer surgical and medical oncology program, including molecular testing and RET-targeted therapy.
BC Cancer Agency (Vancouver): Provincial thyroid cancer program with coordinated surgical, nuclear medicine, and systemic therapy services.
Thyroid Cancer Canada: Patient advocacy organization providing support, education, and clinical trial information. thyroidcancercanada.org

International

United Kingdom: The Christie NHS Foundation Trust (Manchester) and Imperial College Healthcare NHS Trust (London) — major thyroid cancer referral centers. Access to selpercatinib via the Cancer Drugs Fund.
France: Institut Gustave Roussy (Villejuif, Paris) — one of Europe's leading thyroid cancer research centers. Led the ESTIMABL trials that changed RAI practice worldwide.
Japan: Kuma Hospital (Kobe) — the pioneer of active surveillance for papillary thyroid microcarcinoma with 30+ years of follow-up data. Cancer Institute Hospital (Tokyo) — active surveillance and surgical expertise.
South Korea: Samsung Medical Center and Asan Medical Center (Seoul) — high-volume thyroid cancer programs with extensive active surveillance experience.

National organizations

ThyCa: Thyroid Cancer Survivors' Association — the largest thyroid cancer patient organization, offering free support groups, educational materials, low-iodine cookbook, and annual conference. thyca.org
American Thyroid Association (ATA) — clinical guidelines, patient education, and clinical trial information. thyroid.org
NCCN Patient Guidelines for Thyroid Cancer — free patient-friendly version of clinical treatment guidelines. nccn.org
Light of Life Foundation — focused on advanced and aggressive thyroid cancers, funding research and patient support. lightoflifefoundation.org
Bite Me Cancer — supporting young thyroid cancer survivors. bitemecancer.org

Financial assistance

Manufacturer patient assistance programs: Eisai (lenvatinib/Lenvima), Exelixis (cabozantinib/Cabometyx), Eli Lilly (selpercatinib/Retevmo), and other manufacturers offer co-pay assistance and free drug programs for eligible patients.
Patient Advocate Foundation: Case management for insurance issues, appeals, and financial aid. patientadvocate.org
CancerCare: Financial assistance grants, counseling, and support groups. cancercare.org
Thyrogen (rhTSH) access: Genzyme/Sanofi offers patient assistance for Thyrogen. Discuss with your nuclear medicine team if cost is a barrier.

Research and information

ClinicalTrials.gov: The definitive source for finding thyroid cancer clinical trials. clinicaltrials.gov
Thyroid Cancer Genomic Atlas (TCGA): Foundational research on the molecular landscape of thyroid cancer.
PubMed: For patients who want to read the primary research. Searching "[drug name] thyroid cancer" or "[trial name]" will find the key studies.

When to seek a second opinion

Consider referral to a high-volume thyroid cancer center if:

Your cancer is medullary or anaplastic thyroid cancer
You have been told your disease is RAI-refractory
Systemic therapy is being discussed
You are considering active surveillance and want expert guidance
Your cancer has recurred
Lateral neck dissection is being recommended
You have a hereditary thyroid cancer syndrome (MEN2, Cowden)
Your molecular testing shows an uncommon mutation (NTRK fusion, RET fusion in DTC)

Is there a thyroid cancer support group you'd recommend for my situation?
Should I be referred to a specialized thyroid cancer center for any aspect of my care?
Are there clinical trials I should consider given my cancer type and molecular profile?
What financial assistance programs are available for my medications?
Is genetic counseling recommended for my family?
Can you help coordinate a second opinion at [specific center]?

You don't have to do this alone. Connect with ThyCa support groups (online and in-person). Hearing from others on the same journey helps more than almost anything.
Know the care team players. Thyroid cancer care involves multiple specialists: endocrinologist, endocrine surgeon, nuclear medicine physician, medical oncologist (for advanced disease), genetic counselor (for hereditary types). Keep a contact list with each provider's role.
Organize medical records. Keep copies of pathology reports, molecular testing results, RAI treatment summaries, ultrasound reports, and lab trends. You will reference these at every new appointment.
Ask about caregiver support. HCI and other major centers offer caregiver support programs, counseling services, and respite resources.

Key References

Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016;26(1):1–133.
Wells SA Jr, Asa SL, Dralle H, et al. Revised American Thyroid Association Guidelines for the Management of Medullary Thyroid Carcinoma. Thyroid. 2015;25(6):567–610.
NCCN Clinical Practice Guidelines in Oncology: Thyroid Carcinoma. Version 3.2026.
Filetti S, Durante C, Hartl D, et al. Thyroid cancer: ESMO Clinical Practice Guidelines. Ann Oncol. 2019;30(12):1856–1883. Updated 2024.
Schlumberger M, Tahara M, Wirth LJ, et al. Lenvatinib versus placebo in radioiodine-refractory thyroid cancer (SELECT). N Engl J Med. 2015;372(7):621–630. (NCT01321554)
Brose MS, Nutting CM, Jarzab B, et al. Sorafenib in radioactive iodine-refractory, locally advanced or metastatic differentiated thyroid cancer (DECISION). Lancet. 2014;384(9940):319–328. (NCT00984282)
Brose MS, Robinson B, Sherman SI, et al. Cabozantinib for radioiodine-refractory differentiated thyroid cancer (COSMIC-311). Lancet Oncol. 2021;22(8):1126–1138. (NCT03690388)
Wirth LJ, Sherman E, Robinson B, et al. Efficacy of selpercatinib in RET-altered thyroid cancers (LIBRETTO-001). N Engl J Med. 2020;383(9):825–835. (NCT03157128)
Hadoux J, Elisei R, Brose MS, et al. Phase 3 trial of selpercatinib in advanced RET-mutant medullary thyroid cancer (LIBRETTO-531). N Engl J Med. 2023;389(20):1851–1861. (NCT04211337)
Subbiah V, Kreitman RJ, Wainberg ZA, et al. Dabrafenib plus trametinib in BRAF V600E-mutant anaplastic thyroid cancer (ROAR). J Clin Oncol. 2022;40(29):3438–3448. (NCT02034110)
Leboulleux S, Bournaud C, Baudin E, et al. Thyroidectomy without radioiodine in patients with low-risk thyroid cancer (ESTIMABL2). N Engl J Med. 2022;386(10):923–932. (NCT01837745)
Ito Y, Miyauchi A, Kihara M, et al. Overall survival of papillary thyroid carcinoma patients treated during 1960–2019: a long-term follow-up study. Thyroid. 2024.
Cibas ES, Ali SZ. The 2023 Bethesda System for Reporting Thyroid Cytopathology (3rd edition). Thyroid. 2023;33(9):1039–1044.

Glossary

DTC (Differentiated Thyroid Cancer) — The most common group of thyroid cancers, including papillary and follicular types. "Differentiated" means the cancer cells still somewhat resemble normal thyroid cells and usually respond well to treatment.
PTC (Papillary Thyroid Cancer) — The most common type of thyroid cancer, accounting for about 80% of cases. It tends to grow slowly and has an excellent prognosis when caught early.
FTC (Follicular Thyroid Cancer) — The second most common type of thyroid cancer, making up about 10–15% of cases. It can sometimes spread to distant sites like the lungs or bones but is generally very treatable.
MTC (Medullary Thyroid Cancer) — A less common thyroid cancer that arises from C-cells, which produce calcitonin. About 25% of cases are hereditary, linked to RET gene mutations.
ATC (Anaplastic Thyroid Cancer) — A rare but aggressive form of thyroid cancer that grows and spreads quickly. It requires urgent, multimodal treatment and accounts for fewer than 2% of thyroid cancers.
Bethesda Classification — A standardized six-category system used to report the results of thyroid nodule biopsies. Each category (Bethesda I through VI) indicates a different level of cancer risk, guiding decisions about whether surgery or monitoring is needed.
FNA (Fine-Needle Aspiration) — A biopsy procedure where a thin needle is inserted into a thyroid nodule to collect cells for examination under a microscope. It is the primary method for determining whether a nodule is cancerous.
Afirma GSC — A genomic sequencing classifier test used on indeterminate thyroid biopsy samples. It analyzes gene expression patterns to help determine whether a nodule is likely benign, potentially avoiding unnecessary surgery.
ThyroSeq — A molecular test that looks for specific DNA and RNA alterations in thyroid biopsy samples. It helps clarify whether indeterminate nodules are likely benign or malignant and can identify targetable mutations.
RAI (Radioactive Iodine) — A treatment that uses a radioactive form of iodine (I-131) to destroy remaining thyroid tissue or cancer cells after surgery. Thyroid cells naturally absorb iodine, so the radiation is highly targeted.
TSH Suppression — A treatment strategy where levothyroxine (thyroid hormone) is dosed to keep TSH levels below normal. This reduces stimulation of any remaining thyroid cancer cells, lowering the risk of recurrence.
Thyroglobulin — A protein produced by thyroid cells, used as a tumor marker after treatment for differentiated thyroid cancer. Rising thyroglobulin levels in follow-up bloodwork may signal that cancer has returned.
RET Mutation — A change in the RET gene that drives the growth of certain thyroid cancers, especially medullary thyroid cancer. Targeted therapies like selpercatinib can block the faulty RET protein.
BRAF V600E — A specific mutation in the BRAF gene commonly found in papillary thyroid cancer. Its presence can influence treatment decisions and may indicate a slightly higher risk of recurrence in some cases.
NTRK Fusion — A genetic alteration where part of an NTRK gene fuses with another gene, creating a protein that drives cancer growth. FDA-approved drugs (larotrectinib, entrectinib) can target this fusion regardless of cancer type.
Selpercatinib — A targeted therapy drug that specifically blocks the RET protein. It is FDA-approved for RET-mutant medullary thyroid cancer and RET-fusion thyroid cancer that has not responded to other treatments.
Lenvatinib — A multi-kinase inhibitor drug used to treat radioactive-iodine-refractory differentiated thyroid cancer. It works by blocking signals that help tumors grow new blood vessels and proliferate.
Active Surveillance — A management approach for very low-risk thyroid cancers (typically papillary microcarcinomas under 1 cm) where the tumor is monitored with regular ultrasounds instead of immediate surgery. Surgery remains an option if the cancer shows signs of growth.
Dynamic Risk Stratification — An ongoing assessment approach where a patient's risk of recurrence is updated over time based on how they respond to treatment, rather than relying solely on the initial staging at diagnosis.
Calcitonin — A hormone produced by C-cells in the thyroid gland. It serves as the primary tumor marker for medullary thyroid cancer; rising calcitonin levels may indicate disease progression or recurrence.
CEA (Carcinoembryonic Antigen) — A protein that can be elevated in the blood of patients with medullary thyroid cancer. It is tracked alongside calcitonin as a tumor marker to monitor disease status over time.

Appendix · For discussion with your medical team

Recovery from thyroid surgery is typically straightforward for most patients. Pain is mild and managed with acetaminophen; sore throat from the breathing tube resolves in a few days. You may speak with a temporarily hoarse voice if the nerve near the thyroid was affected during surgery — this usually improves within weeks to months, but your surgeon will monitor it. Calcium levels should be checked the first day after surgery: the parathyroid glands sit near the thyroid and can be temporarily affected, causing low calcium (numbness or tingling around the mouth, fingertips, or muscle cramps). Calcium supplements and vitamin D are prescribed if needed. Activity can resume gradually over 1–2 weeks; most patients return to work within 1–2 weeks for desk jobs and 2–4 weeks for physical work. The neck incision heals well with scar tape and sun protection. Thyroid hormone replacement (levothyroxine) begins the morning after surgery or within a few days for total thyroidectomy.

Testing Treatments on a Copy of Your Own Tumor

When a thyroid tumor is removed, surgeons often recover more tissue than the pathology lab needs for diagnosis. Researchers have learned how to take that leftover tissue and grow it in the laboratory — creating small living replicas of your specific cancer. Once those replicas are established, scientists can expose them to dozens of drugs or drug combinations and measure which ones shrink or kill the cancer cells most effectively. The idea is to give your oncologist real data about your particular tumor before committing to a treatment — rather than relying solely on population-level statistics about what works for most people with thyroid cancer.

The most important thing to know: Tumor functional testing for thyroid cancer is still investigational. It is not a standard part of thyroid cancer care, and results are not guaranteed to be available in time to guide your first treatment decision. It works best when planned before surgery — not after. Think of it as additional information to consider alongside your oncologist's standard recommendations, not as a replacement for them.

The basic idea

Most thyroid cancers — papillary, follicular, and medullary — are slow-growing and highly treatable with surgery, radioactive iodine, or targeted drugs. But anaplastic thyroid cancer (ATC) is a different situation entirely: it is one of the most aggressive solid tumors known, with a median survival often measured in months, and standard regimens do not work well for most patients. That urgency makes ex vivo drug testing especially relevant for ATC, where finding an effective combination quickly can matter enormously. Even for differentiated thyroid cancers that stop responding to radioactive iodine or acquire resistance to kinase inhibitors such as lenvatinib or sorafenib, learning which drug your specific tumor responds to — rather than cycling through options by trial and error — is exactly the problem these models are designed to address. Because thyroidectomy is a common and well-established surgery, tissue availability is generally excellent compared with many other cancer types, which removes one of the main practical barriers to this kind of testing.

The main approaches, from fastest to slowest

Tumor Organoids (3-D Mini-Tumors in a Dish)

Typical turnaround: 2–4 weeks · Tissue source: Thyroidectomy specimen or core biopsy · Establishment rate: ~60–75% for papillary; higher success for anaplastic

A small piece of your thyroid tumor is processed into single cells, then suspended in a gel-like matrix where the cells self-organize into tiny three-dimensional clusters that mimic the architecture of the original tumor. Organoids have been successfully established from both papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC). Because ATC grows rapidly in the body, it also tends to grow rapidly in the lab — organoids from ATC can sometimes be tested within two weeks of surgery, which aligns with the urgency of the disease. Drug panels can screen 20 or more agents simultaneously. Results from organoid testing have shown reasonable correlation with clinical drug response in early studies, though large validation trials have not yet been completed.

Zebrafish Avatars

Typical turnaround: 1–2 weeks · Tissue source: Fresh tumor cells from thyroidectomy or biopsy · Establishment rate: Variable; requires fresh viable cells

Your tumor cells are injected into zebrafish embryos, which are transparent and develop very quickly. Within days, researchers can watch whether the human cancer cells grow and spread, and then treat the fish with different drugs to see which ones stop tumor growth. The method is extremely fast — the fastest of all the platforms described here — and can screen many drugs in parallel. For thyroid cancer, zebrafish models have been used in research settings to study tumor invasion and test kinase inhibitors, including drugs that target the BRAF V600E mutation common in papillary thyroid cancer. Access outside specialized research programs is very limited, but the speed makes it theoretically well-suited to ATC.

Chorioallantoic Membrane (CAM) Assay

Typical turnaround: 1–2 weeks · Tissue source: Fresh tumor fragment or cell suspension · Establishment rate: Moderate; less commonly used than organoids

Tumor cells or small tumor fragments are placed onto the surface of a fertilized chicken egg membrane, where they receive a blood supply and continue to grow in a living environment. Drugs can then be applied and their effect on tumor growth measured. The CAM assay sits between organoids and mouse models in terms of biological complexity — it provides a vascularized environment without requiring months of animal work. It is less commonly used for thyroid cancer than organoids, but research groups have used it to study thyroid tumor biology and drug response in experimental settings.

Patient-Derived Xenografts (PDX) — Mouse Models

Typical turnaround: 3–6 months · Tissue source: Surgical specimen · Establishment rate: ~30–50% for differentiated thyroid cancer; higher for ATC

A portion of your tumor is implanted into mice that have been engineered to lack an immune system, so they do not reject human tissue. The tumor grows in the mouse, and then different drugs are tested. PDX models are considered the closest approximation to the original tumor among all laboratory platforms, but the time required — typically three to six months — makes them impractical for guiding urgent treatment decisions. They are most useful for understanding biology and testing drugs for future patients rather than informing your own immediate care.

What the evidence says so far

The evidence base for tumor functional testing in thyroid cancer is still early. Most published work consists of case reports, small series, and proof-of-concept studies rather than prospective randomized trials.

Organoid models have been established from ATC in multiple academic centers and used to identify drug sensitivities, including responses to BRAF/MEK inhibitor combinations and immunotherapy agents, in individual patients.
A 2022 study from the Mayo Clinic demonstrated successful organoid establishment from ATC specimens and showed that drug response patterns in organoids aligned with clinical outcomes in a small series of patients.
PDX models for ATC have been used to validate BRAF V600E-targeted therapy responses before clinical use and to study mechanisms of resistance to dabrafenib/trametinib combinations.
No large prospective trial has yet compared treatment outcomes for patients who received organoid-guided therapy versus standard-of-care selection in thyroid cancer specifically.

Anaplastic thyroid cancer is a special case: Because ATC is so rapidly progressive, the window for tissue collection, organoid establishment, and drug testing may close before results are available. If you or a family member has ATC, this conversation must happen immediately — ideally before surgery — so the surgical team can coordinate tissue collection with a laboratory that has an active program. Do not wait until after pathology is complete.

How tissue is collected and what happens to it

If you and your oncologist decide to pursue functional testing, the process typically works as follows:

Coordination before surgery: Your surgeon contacts the laboratory to arrange same-day tissue transfer. Fresh tissue — not formalin-fixed — is required. This must be arranged in advance; it cannot be done retroactively on stored specimens.
Tissue allocation: The pathologist takes the tissue needed for diagnosis first. Remaining tumor is divided: a portion goes to the functional testing laboratory, often in a special transport medium supplied by the lab.
Processing: The laboratory dissociates the tumor into single cells or small clusters and begins growing them. This step may fail if too few viable cells are recovered, which is why establishment rates are not 100%.
Drug screening: Once the model is established, a panel of drugs — often 20 to 40 agents — is applied at multiple concentrations. Automated imaging measures cell death or growth inhibition for each drug.
Report generation: The laboratory provides a ranked list of agents by sensitivity, often with an interpretation note. This report goes to your oncologist, who considers it alongside genomic testing results, standard guidelines, and your overall health status.

Genomic testing versus functional testing — two different questions

Your oncologist may already have ordered molecular profiling of your tumor — tests such as ThyroSeq, Afirma, or next-generation sequencing panels that look for mutations including BRAF V600E, RET fusions, NTRK fusions, RAS mutations, and others. These tests identify what genetic changes are driving your tumor. Functional testing asks a related but distinct question: given those changes and everything else about your particular cancer cells, which drugs actually kill them?

The two approaches are complementary, not competitive. A BRAF V600E mutation predicts that your tumor may respond to BRAF-targeted drugs — functional testing can confirm whether it does in your specific cells, and may reveal that a combination works better than a single agent. Conversely, functional testing sometimes reveals sensitivity to a drug that genomic profiling would not have predicted, because drug response depends on the entire cellular context, not just a single mutation.

Questions to ask your oncologist or surgeon before pursuing this

Is my tumor type and stage one where functional testing results are likely to come back in time to influence my initial treatment decision?
Does this institution, or a partner laboratory, have an active program for thyroid cancer organoids or other functional testing platforms?
If I have anaplastic thyroid cancer, can tissue collection be coordinated before or at the time of surgery — today?
How will functional testing results be integrated with my molecular profiling results and with standard treatment guidelines?
What is the cost, and is any portion covered by insurance or available through a clinical trial?
If the model fails to establish, what is the plan?
Are there clinical trials at this center that use functional testing to guide treatment assignment?

Finding programs and clinical trials

Tumor functional testing for thyroid cancer is available primarily through academic medical centers with dedicated translational research programs. There is no widely available commercial service for thyroid cancer organoids comparable to what exists for some other tumor types.

To find active programs:

Search ClinicalTrials.gov for "thyroid cancer organoid," "thyroid cancer patient-derived," or "anaplastic thyroid cancer ex vivo" — filter to recruiting studies.
Contact the endocrine surgery or endocrine oncology program at a National Cancer Institute-designated comprehensive cancer center. In the Mountain West, the Huntsman Cancer Institute at the University of Utah (801-585-0303) and Mayo Clinic (507-284-2111) have active thyroid cancer research programs.
Ask specifically whether their laboratory has an ongoing tissue banking protocol for thyroid cancer that includes functional testing.

Summary comparison

Platform	Speed	Biological fidelity	Access	Best for
Zebrafish avatar	1–2 weeks	Moderate	Research only	Rapid screening; ATC urgency
CAM assay	1–2 weeks	Moderate	Research only	Vascularized environment; speed
Tumor organoid	2–4 weeks	Good	Selected academic centers	PTC, FTC, ATC drug screening
PDX mouse model	3–6 months	Very high	Research only	Biology research; future patients

ATC: Anaplastic thyroid cancer — the most aggressive subtype, accounting for fewer than 2% of thyroid cancers but a disproportionate share of thyroid cancer deaths.
BRAF V600E: A mutation found in approximately 60% of papillary thyroid cancers that drives tumor growth and predicts response to BRAF-targeted drugs such as vemurafenib and dabrafenib.
CAM assay: Chorioallantoic membrane assay — a method that grows tumor cells on a chicken egg membrane to test drug effects in a living, vascularized environment.
Ex vivo: Outside the living body — refers to experiments performed on tissue removed from a patient and kept alive in the laboratory.
Organoid: A three-dimensional miniature tissue grown in the laboratory from a patient's own cells that mimics the structure and behavior of the original tumor.
PDX: Patient-derived xenograft — a model in which human tumor tissue is implanted into immune-deficient mice to study drug effects.
PTC / FTC: Papillary thyroid cancer / follicular thyroid cancer — the two most common subtypes of differentiated thyroid cancer, generally slow-growing and highly treatable.
Tumor functional testing: Laboratory testing that measures how a patient's actual tumor cells respond to drugs, as opposed to predicting response based on genetic mutations alone.

This appendix describes investigational research approaches that are not standard medical care. It is intended to help you have informed conversations with your medical team — not to replace their recommendations. All treatment decisions should be made in consultation with your oncologist and care team.

A Research Guide forThyroid Cancer

⚡ Quick Start — If You Read Nothing Else

Overview — Understanding Thyroid Cancer in 2026

What has changed recently

Diagnosis & Molecular Testing

The Bethesda system — your biopsy result explained

Molecular testing — avoiding unnecessary surgery

What your molecular profile means

Surgery, Radioactive Iodine & Targeted Therapy

Surgery — the foundation of treatment

Radioactive iodine (RAI) therapy

TSH suppression — levothyroxine as therapy

Targeted therapy — when cancer is advanced

Monitoring & Survivorship

Dynamic risk stratification — your risk changes over time

Thyroglobulin — your key blood marker

Monitoring schedule

Living well with thyroid cancer

What to avoid on LID (2 weeks before RAI):

What IS allowed:

The TSH boost — two options:

After RAI — radiation precautions:

Advanced Disease & Clinical Trials

Treatment sequencing for RAI-refractory differentiated thyroid cancer

Redifferentiation therapy — restoring RAI sensitivity

Immunotherapy in thyroid cancer

Next-generation targeted agents

Key clinical trials — past and ongoing

Finding and joining clinical trials

International Access & Regulatory Landscape

Failed & De-Adopted Therapies

External beam radiation for routine low-risk DTC

Routine high-dose RAI for low-risk papillary thyroid cancer

Selumetinib (AZD6244) as standalone RAI-refractory DTC treatment

Pralsetinib (Gavreto) — US market withdrawal

Doxorubicin monotherapy for advanced thyroid cancer

Routine total thyroidectomy for all thyroid cancers

Thyroid hormone suppression to undetectable TSH in all patients

Support & Resources

Mountain West / Utah

US National

Veterans

Canada

International

National organizations

Financial assistance

Research and information

When to seek a second opinion

Key References

Glossary

Testing Treatments on a Copy of Your Own Tumor

The basic idea

The main approaches, from fastest to slowest

Tumor Organoids (3-D Mini-Tumors in a Dish)

Zebrafish Avatars

Chorioallantoic Membrane (CAM) Assay

Patient-Derived Xenografts (PDX) — Mouse Models

What the evidence says so far

How tissue is collected and what happens to it

Genomic testing versus functional testing — two different questions

Questions to ask your oncologist or surgeon before pursuing this

Finding programs and clinical trials

Summary comparison

Post-Treatment Surveillance and Long-Term Monitoring

⚠️ Safety Warnings & Critical Drug Risks

Radioactive Iodine (I-131) — Radiation Precautions & Pregnancy Contraindication

Levothyroxine Interactions & TKI Safety (Lenvatinib/Sorafenib/Vandetanib)

A Research Guide for
Thyroid Cancer