Risk Factors of Synchronous Breast and Thyroid Cancer: a Controlled Multicenter Study and Review of the Literature.

Background: Breast cancer (BC) is one of the most common cancers diagnosed in women in the United States. Thyroid cancer (TC) is also one of the fastest increasing cancer types in the United States, with most cases being papillary thyroid carcinomas.

Objective: To identify possible risk factors for the synchronous or metachronous co-occurrence of breast and thyroid cancers.