Although thyroid cancer occurs in all age-groups, patients who have had radiation therapy in the neck area are especially susceptible. Papillary and follicular carcinomas are common forms of thyroid cancers and are usually associated with the longest survival times.

Papillary carcinoma accounts for about half of thyroid cancer cases in adults. It can occur at any age but is most common in young adult females. Usually multifocal and bilateral, it metastasizes slowly into regional nodes of the neck, mediastinum, lungs, and other distant organs. It’s the least virulent form of thyroid cancer.

Less common, follicular carcinoma is more likely to recur and metastasize to the regional lymph nodes and spread through blood vessels into the bones, liver, and lungs.

Medullary (solid) carcinoma originates in the parafollicular cells derived from the last branchial pouch and contains amyloid and calcium deposits. It can produce calcitonin, histaminase, corticotropin (producing Cushing’s syndrome), and prostaglandin E₂ and F₃ (producing diarrhea). This form of thyroid cancer is familial, possibly inherited as an autosomal dominant trait, and usually associated with pheochromocytoma and is curable when detected before it causes symptoms. Untreated, it grows rapidly, frequently metastasizing to bones, liver, and kidneys.

Anaplastic carcinoma is a giant and spindly cancer that resists radiation and is almost never curable by resection. Tumors usually occur in older patients with a long history of goiter. This cancer metastasizes rapidly, causing death by invading the trachea and compressing adjacent structures. It accounts for between 10% and 15% of thyroid cancers.