Familial Nonmedullary Thyroid Cancer

Approximately 3% to 9% of all nonmedullary thyroid cancers (NMTCs) are inherited. Familial nonmedullary thyroid cancer (FNMTC) may be part of familial cancer syndromes (syndromic) or the predominant or only feature (nonsyndromic). The majority of FNMTCs are nonsyndromic (95%). Syndromic FNMTCs include familial adenomatous polyposis (FAP); PTEN hamartoma tumor syndrome; Carney complex type 1; Werner, Pendred, and DICER1 syndromes; and ataxia-telangiectasia. Although the risk of thyroid cancer is higher in syndromic FNMTC than in the general population, it is commonly a minor component with incomplete penetrance. On the other hand, nonsyndromic FNMTC has an autosomal-dominant pattern of inheritance and is associated with more aggressive disease than sporadic NMTC. In this chapter, we discuss screening for FNMTC, the clinical and pathologic features of syndromic and nonsyndromic FNMTC, and the treatment of patients with FNMTC.