Thyroid cancer

Most thyroid nodules are not cancer. Ultrasound assesses the nodule and neck nodes, and guides whether a needle sample is needed. Normal thyroid hormone tests do not exclude cancer. A growing neck lump, persistent hoarseness or swallowing difficulty needs assessment; noisy breathing or breathlessness requires urgent care.

WHO classification distinguishes papillary, follicular and oncocytic carcinomas, high-grade follicular-derived cancers, medullary carcinoma and anaplastic carcinoma. Oncocytic carcinoma is the current name for what older reports may call Hürthle cell carcinoma. High-grade or poorly differentiated components change the risk assessment.

“Follicular neoplasm” on a needle sample is not a definite diagnosis of follicular carcinoma. Establishing invasion into the capsule or blood vessels often requires removed tissue. Clarify whether the report means confirmed cancer, an indeterminate sample or a low-risk neoplasm such as NIFTP.

AJCC stage combines tumor extent, nodes and distant spread. In differentiated thyroid cancer, age also affects stage grouping. Medullary cancer has a different grouping; all anaplastic cancers fall within stage IV, including those without distant spread. Stage numbers cannot be compared directly across these types.

Recurrence risk asks how likely disease is to remain or return. Pathology, invasion and nodal burden inform the initial estimate; ultrasound, blood markers and response refine it over time. A small tumor with adverse findings should not be judged by diameter alone.

The 2025 ATA guideline allows active surveillance for selected adults with cT1aN0M0 papillary cancer: no larger than 1 cm, without clinical nodal or distant disease. Favorable location and reliable long-term ultrasound follow-up are essential. Aggressive pathology, invasion or a threatening location changes suitability.

The same guideline conditionally allows ultrasound-guided percutaneous ablation in selected patients in this group, with low-certainty evidence. Radiofrequency or microwave treatment requires an experienced team to assess the whole lesion and nearby nerves. Compare surveillance, ablation and surgery; ablation still requires follow-up and may need further treatment.

For tumors up to 2 cm without gross extrathyroidal extension or clinical metastases, the 2025 ATA guideline recommends initial lobectomy when surgery is chosen, unless bilateral cancer or another indication calls for total thyroidectomy. Selected low-risk, unilateral tumors over 2 cm and up to 4 cm may also be treated with lobectomy.

Larger or invasive disease, involved nodes, findings in the other lobe and a plan for radioactive iodine may favor total thyroidectomy. Neck dissection is tailored to nodal disease and risk. Completion surgery after lobectomy depends on final pathology and the treatment goal, not simply the word “cancer.”

Discuss voice and swallowing function, nerve injury and low calcium from parathyroid damage. These risks matter when comparing an adequate smaller operation with a larger one. Invasive disease or repeat surgery particularly benefits from a team experienced in that procedure.

Radioactive iodine works on cells that retain iodine uptake. It is not routine after every differentiated cancer operation and does not treat medullary or anaplastic cancer. Clarify the proposed aim: remnant ablation, additional treatment for recurrence risk, or treatment of known iodine-avid disease.

Preparation may include a low-iodine diet and raising TSH with medication or temporary hormone withdrawal. Review iodine contrast and supplements. Pregnancy and breastfeeding preclude treatment; discuss fertility, future pregnancy and written radiation-safety instructions before scheduling.

Dry mouth, salivary-gland injury and cumulative exposure matter. Repeating iodine when disease no longer takes it up or progresses despite adequate treatment may add harm without useful control. Ask what finding would justify another course.

A single neck recurrence, a few growing metastases and widespread progression need different plans. Surgery, focused radiation or ablation may address limited disease. Slowly changing, asymptomatic disease may be monitored; continuous systemic treatment depends on pace, symptoms and organ threats, not a positive scan alone.

Molecular testing can identify selective treatment. US selpercatinib covers patients aged 2 or older with RET fusion-positive advanced or metastatic thyroid cancer requiring systemic therapy and radioactive iodine resistance when iodine is appropriate. This fusion indication differs from the RET mutation indication in medullary cancer.

An NTRK fusion may support a TRK inhibitor under its label; expression alone is insufficient. US larotrectinib also requires metastatic disease or surgery likely to cause severe morbidity, and no satisfactory alternative or progression after treatment.

US lenvatinib monotherapy is used for adults with progressive, locally recurrent or metastatic iodine-refractory differentiated cancer. Cabozantinib tablets cover patients aged 12 or older with locally advanced or metastatic disease progressing after VEGFR-targeted treatment and refractory or ineligible for iodine. Blood pressure, proteinuria, weight loss, diarrhea, bleeding and wound risks need monitoring. Confirm access and sequencing in the treatment country.

Medullary cancer arises from C cells. Calcitonin and CEA help assess and monitor it; thyroglobulin is not its main marker. Offer germline RET testing and counseling even without a family history. A tumor-only mutation differs from an inherited variant affecting relatives.

MEN2 assessment includes pheochromocytoma and, when relevant, parathyroid disease. An unrecognized pheochromocytoma can make thyroid surgery dangerous and needs identification and management first. Relatives carrying a germline RET variant need a specialist plan based on the variant and age.

Surgery is central for localized disease; radioactive iodine has no role. For advanced or metastatic RET-mutant medullary cancer requiring systemic treatment, US selpercatinib is approved from age 2 without requiring prior vandetanib failure. Marker changes should be interpreted with scans and disease tempo.

Rapid neck enlargement, airway pressure and swallowing problems can develop quickly. Confirm pathology, assess the airway and disease extent, and obtain urgent BRAF V600E testing with broader testing when feasible. Airway planning and symptom support proceed alongside treatment decisions.

Surgery, radiation and systemic therapy are combined according to resectability and patient goals. US dabrafenib plus trametinib is approved for BRAF V600E-positive locally advanced or metastatic anaplastic cancer without satisfactory locoregional options. A response may allow reassessment, but does not guarantee surgery or cure.

Total thyroidectomy requires lifelong hormone replacement; after lobectomy the remaining gland may or may not produce enough. Take medication consistently and review calcium, iron and other products that affect absorption. Unexpected blood results may also reflect testing interference.

Not everyone needs lifelong, extreme TSH suppression. Current guidance adjusts the target to disease and response, balancing benefit against heart-rhythm and bone risks. Medullary cancer does not require cancer-directed TSH suppression. Do not change the dose using a generic online target.

For differentiated cancer, neck ultrasound and appropriately selected thyroglobulin and antibody measurements help monitor response. A detectable thyroglobulin after lobectomy is not automatically recurrence because normal thyroid remains. Persistent hoarseness, low-calcium symptoms or new neck findings deserve earlier assessment.

Bring cytology and surgical pathology, ultrasound images, the operative report, prior iodine treatments and scans, and a dated series of TSH, thyroglobulin and antibody results. For MTC, add calcitonin, CEA and germline/tumor RET reports. Advanced disease review needs the full molecular report and previous treatment record.

Ask: What makes this low or high risk? What would trigger treatment during monitoring? Is a smaller operation sufficient? What should iodine achieve? Why start systemic treatment now, and which result supports the selected drug?