Hereditary non-medullary thyroid cancer.

An estimated 5% of all non-medullary thyroid cancers are hereditary. If three or more first-degree relatives are affected, there is a greater than 94% chance that these cases are hereditary non-medullary thyroid cancer (HNMTC). Although, the susceptibility gene(s) for HNMTC has not been identified, there are enough epidemiologic studies and kindreds reported to suggest a hereditary predisposition to thyroid cancer. Until the susceptibility genes are identified, clinicians will have to rely on comprehensive history taking to identify at-risk families and clinically screen at-risk family members. When families are at risk for HNMTC, it is unclear whether neck examination and or neck ultrasound is most effective for screening. Hereditary non-medullary thyroid cancer is associated with more aggressive disease than sporadic HNMTC, especially in index cases, with higher rates of multicentric tumors, lymph node metastasis, and extrathyroidal invasion. Aggressive screening may benefit other members of the affected kindred because the outcome for the non-index cases is better. Although no studies have demonstrated any difference in mortality in patients with HNMTC versus sporadic disease, disease-free survival is shorter in HNMTC. Aggressive surgical and postoperative medical therapy is warranted in patients with HNMTC. It is likely that emerging molecular approaches may help identify the gene or genes involved in HNMTC which would have important clinical ramifications.