Follicular Thyroid Cancer
Follicular thyroid cancer (FTC) is the second most common differentiated thyroid cancer. It arises from follicular cells and, unlike papillary cancer, cannot reliably be diagnosed by needle biopsy alone — diagnosis requires surgical pathology.
It is less common than papillary cancer but carries a slightly higher risk of distant spread.
Last medically reviewed: 1 November 2025
Features and diagnosis
FTC typically presents as a solitary thyroid nodule. FNAC can identify follicular cells but cannot distinguish a benign follicular adenoma from carcinoma — this requires examining the tumour capsule for invasion. Minimally invasive FTC has an excellent prognosis; widely invasive FTC carries more risk.
Ultrasound and clinical assessment guide whether lobectomy or total thyroidectomy is planned.
Treatment
Surgery is the mainstay. Total thyroidectomy is often preferred for FTC because it enables radioactive iodine treatment if needed and simplifies thyroglobulin surveillance.
Radioactive iodine ablation is considered for tumours with high-risk features — capsular or vascular invasion, larger size, or distant spread. Levothyroxine replaces hormone and suppresses TSH as indicated.
Prognosis and follow-up
Most FTC patients do well. Widely invasive or metastatic disease has a more guarded outlook but remains treatable with radioactive iodine and, in some cases, targeted therapies.
Follow-up mirrors papillary cancer: TSH suppression, thyroglobulin monitoring and periodic neck ultrasound.
Frequently asked questions
Why couldn’t my biopsy confirm cancer?
Follicular lesions are cytologically indistinguishable — cells look identical whether the tumour is benign or malignant. The distinction is made by examining the surgical specimen for capsular or vascular invasion.
Does follicular cancer spread to bones or lungs?
Widely invasive FTC can metastasise, most often to lung and bone. These metastases often still take up iodine and can be treated with radioactive iodine.
Is FTC hereditary?
Sporadic FTC is not typically inherited. Rare familial syndromes exist, and your doctor may suggest genetic counselling if there is a strong family history.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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