Multiple Endocrine Neoplasias

Abstract Multiple endocrine neoplasia (MEN), types 1 and 2 (MEN1, MEN2) are autosomal dominant hereditary syndromes that predispose to wide variety of both hormone‐secreting and nonsecreting tumours throughout the body. MEN1 most classically demonstrates neoplasia of the parathyroid glands, anterior pituitary and neuroendocrine tumours of the pancreas and foregut. MEN2 has several variants, but medullary carcinoma of the thyroid is the dominant feature in all. Understanding of the molecular genetics of each disease has greatly affected treatment, especially for MEN2, which generally carries a worse prognosis. Therapy has evolved from symptomatic management of clinically detected tumours to resection of susceptible tissues even prior to tumour development based on genetic testing. This has vastly improved the outcomes for patients with these disorders. Key Concepts: The multiple endocrine neoplasia (MEN) syndromes are hereditary cancer syndromes that drive selected tissues in the body to develop both benign and malignant tumours. Like most other hereditary cancer syndromes, MEN syndromes cause tumour growth by causing unregulated cell growth in susceptible tissues. Unlike most hereditary cancer syndromes, MEN syndromes predominantly cause tumour growth in endocrine tissues, which can produce manifestations of hormone excess in affected patients. Although MEN syndromes are relatively rare, patients with suspicious clinical presentations should undergo genetic testing, as the consequences of a missed MEN diagnosis can be catastrophic in certain variants of the disease. Treatment of MEN syndromes is primarily via surgery, although medical therapy plays an important role for certain manifestations of the disease. The evolution of MEN therapy is a prototype for demonstrating how molecular genetics can improve disease management.