Medullary thyroid carcinoma in children.

Medullary cancer of the thyroid (MCT) in children, although uncommon, represents not only a most intriguing problem but also one that is a model of early cancer detection that results in cure. MCT in children is usually a part of the multiple endocrine neoplasia (MEN) syndrome (MCT, pheochromocytoma, and hyperparathyroidism) and is detected by screening studies. MCT arises from C cells that secrete calcitonin, with C-cell hyperplasia representing the precancerous state. Both are diagnosed by measuring calcitonin levels both basally and after stimulation with pentagastrin. Screening studies should begin shortly after birth in infants at risk for MEN IIb and by age 1 year in children at risk for MEN IIa. Application of this approach should result in near elimination of the spread of cancer in children with MCT.