ABSTRACT
Medullary thyroid carcinoma (MTC) accounts for approximately 4% of all thyroid malignancies (1). Familial MTC occurs with equal frequency in both sexes, while sporadic MTC has a female/male ratio of 1.5:1. Only about 10% to 20% of MTC cases occur as familial tumors. The other 80% to 90% are sporadic and may occur at any age, but usually are detected later in life than familial MTC. For instance, the median age of patients with sporadic MTC seen at the Mayo Clinic was 51 years, compared with 21 years for those with familial tumors (2). Familial Non-MEN Medullary Thyroid Carcinoma (FMTC) is usually detected later, around 40 to 50 years, as compared with an average age of 20 to 30 years for Multiple Endocrine Neoplasia type 2A (MEN-2A) when detected by screening affected kindreds with calcitonin tests. The diagnosis is made even earlier now that genetic testing is available.
