Familial nonmedullary thyroid cancer.

Familial nonmedullary thyroid cancer (FNMTC) is a syndrome of familial clustering of thyroid cancers of follicular cell origin. It is characterized by multifocality, early onset, more recurrences, and a higher degree of aggressiveness than nonfamilial thyroid cancers of follicular cell origin. An autosomal dominant inheritance pattern with reduced penetrance appears likely in most pedigrees. Although several candidate genes responsible for isolated clinical variants of FNMTC have been identified in single families, the gene(s) responsible for the vast majority of FNMTC cases has yet to be identified. Members of FNMTC cohorts should be followed longitudinally with physical examination and ultrasonography, and aggressively treated when cancer is diagnosed. When cancer is diagnosed, total thyroidectomy should be performed, and most patients should have a prophylactic central neck dissection and a therapeutic lateral functional neck dissection, postoperative radioiodine ablation and thyroid-stimulating hormone (TSH) suppressive therapy. Close follow-up with stimulated thyroglobulin levels, neck ultrasounds, and radioiodine scans are also central to the management strategy.