Clinical characteristics and outcome of familial nonmedullary thyroid cancer: a retrospective controlled study.

Background: Familial nonmedullary thyroid cancer (FNMTC) is a disease defined by clustering of thyroid cancers of follicular cell origin, and it is estimated to account for 5% of all thyroid cancers. Several studies found FNMTC to be more aggressive than sporadic disease, whereas others found them to have a similar course and outcome. The purpose of this study was to determine whether FNMTC is more aggressive than sporadic thyroid cancer.