nWDTC’s behave more aggressively, accordingly requiring more aggressive treatment, and have worse prognosis.
- They comprise 10% of all thyroid cancers, and include:
- Poorly Differentiated Thyroid Carcinoma (PDTC, 5%).
- Anaplastic Thyroid Carcinoma (ATC, 1%).
- Both PDTC and ATC also derive from follicular cells of the thyroid and start out as WDTC’s.
- However, after an accumulation of multiple DNA alterations (mutations, gene rearrangements, etc.) they lose all their normal function, and are no longer susceptible to radioactive iodine treatments or visible on whole body iodine scans.
- As the result of multiple DNA alterations, they begin to behave more aggressively – invading nearby structures, spreading more quickly, and more likely to spread to distant sites in the body.
- Medullary Thyroid Carcinoma (MTC, 4%).
- Arise from Parafollicular C Cells in the thyroid gland.
- 25% of patients have germline (hereditary) mutations associated with MEN 2A and 2B syndromes.