What causes thyroid cancer?

The exact cause of thyroid cancer is not known as of 2014, but certain inherited conditions likely contribute, according to the American Cancer Society. Genetic changes or mutations in a person's thyroid typically lead to thyroid cancer.

Papillary cancer is the most common form of thyroid cancer, according to Mayo Clinic. It results from mutation in a person's follicular cells. People from 30 to 50 years old are most afflicted with this form. Follicular thyroid cancer is a distinct form common in people 50 and older. Medullary thyroid cancer develops in C cells. Anaplastic thyroid cancer and thyroid lymphoma are rare forms that grow aggressively.