Comparison of sporadic and hereditary forms of medullary thyroid carcinoma

Between 1960 and 1988, 185 patients with medullary thyroid carcinoma (MTC) were followed at the Institut Gustave Roussy in France. The screening of the family members by calcitonin measurement (basal or after pentagastrin stimulation) has led to the characterization of 38 sporadic cases and 44 hereditary cases. Among the hereditary cases are seven families with MTC only and two families with multiple endocrine neoplasia type 2A (MEN 2A). MTC only cases and MEN 2B cases are present as apparently sporadic forms. Hereditary cases consisted of 26 females and 18 males; the male:female ratio was 21:17 in sporadic cases. Ten of the sporadic patients were deceased (mean age 46 years) compared to three of the hereditary cases (mean age 59 years). The age at diagnosis was 44 years for the sporadic patients and 35 years for the hereditary MTC only patients with clinical manifestations. Histologic data from the sporadic and hereditary patients showed that the tumor is mostly unilateral without C-cell hyperplasia in sporadic cases and bilateral with C-cell hyperplasia in hereditary cases. The location of tumors was quite variable among the sporadic cases and mostly localized to the middle part of the thyroid lobes in the hereditary cases. Our data suggest that the age at diagnosis is later in sporadic forms of MTC and that the age at diagnosis is later in the hereditary forms of MTC only compared to those with MEN 2A.