Papillary thyroid cancer is the most common type, accounting for about 90% of all thyroid cancer cases.
It usually has an excellent prognosis and responds well to treatment. It is the most frequently diagnosed cancer overall. While lymph node metastasis around the thyroid is common, survival rates remain very high with proper surgical treatment.
However, if the cancer spreads beyond the carotid artery and jugular vein into the lateral neck region, the extent of surgery increases significantly. Therefore, accurate preoperative evaluation is essential.

Follicular thyroid cancer accounts for about 10-15% of all thyroid cancers. Many patients initially diagnosed with follicular tumors are confirmed to have follicular cancer in about 10–30% of cases after surgery.
Unlike papillary cancer, follicular cancer rarely metastasizes to lymph nodes but can invade blood vessels and spread to the lungs, bones, or other organs, which may be fatal. Because the diagnosis and treatment of follicular thyroid cancer are more complex than papillary cancer, consultation with a thyroid specialist is essential.

Medullary thyroid cancer (MTC) originates from the thyroid's C-cells, which produce the hormone calcitonin.
It progresses rapidly and has a poorer prognosis compared to other thyroid cancer types. Some cases of MTC are hereditary due to genetic mutations, often running in families as familial medullary thyroid cancer or as part of Multiple Endocrine Neoplasia (MEN) syndromes. If diagnosed with MTC, it is crucial to evaluate family history and conduct genetic testing. In hereditary cases, preventive thyroidectomy may be recommended even if cancer has not yet developed.

These are the rarest but most aggressive types of thyroid cancer, with the worst prognosis. They progress extremely rapidly and frequently invade surrounding tissues or metastasize early. Often, surgery is not possible at the time of diagnosis due to extensive disease. It is known that untreated papillary or follicular thyroid cancer can eventually transform into undifferentiated or anaplastic carcinoma.
Therefore, early diagnosis and treatment of thyroid cancer are critically important.