[Medullary cancer of the thyroid gland].

Thirty-one cases of medullary carcinoma of the thyroid have been studied over the past fifteen years at the University Hospital of the Canton of Vaud, Switzerland (CHUV). Twenty cases were of sporadic nature and eleven presented as part of the familial MEN II syndrome (multiple endocrine neoplasia), one of which showed the classical features of the rare MEN IIb type. It is important to distinguish between the familial and sporadic cases, because membership of the former group implies the investigation of associated endocrinopathies (pheochromocytoma, hyperparathyreoidism) and study of the family tree as the syndrome is autosomal dominant. Medullary carcinoma of the thyroid is a constant feature of the MEN II syndrome and is the cause of premature death in these patients. The familial type should be suspected if the carcinoma appears early in life, is located in the superior pole of the thyroid or is bilateral or multicentric, if the histology shows hyperplasia of the C cells and, of course, if there is a history of surgery for pheochromocytoma or hyperparathyroidism. Although total thyroidecomy is the rule for these familial cases, its role is debatable in sporadic medullary carcinoma of the thyroid. Postoperative follow-up of these patients is based on serum calcitonin determination, as this is an extremely sensitive marker. The ten year survival rate is 50%, with the worst prognosis in MEN IIb type.