Chromogranin A and the alpha-subunit of glycoprotein hormones in medullarythyroid carcinoma and phaeochromocytoma

Using specific immunoradiometric assays, we evaluated the clinical usefulne ss of chromogranin A and the a-subunit of glycoprotein hormones in neuroend ocrine tumours of neuroectodermic origin. The serum cc-subunit of glycoprot ein hormones was only slightly increased in 2 out of 44 medullary thyroid c arcinoma or phaeochromocytoma patients with increased calcitonin or 24-hour urinary metanephrine levels. Serum chromogranin A was increased in 12 of 4 5 (27%) medullary thyroid carcinoma patients with an elevated calcitonin le vel and in 4 of 16 medullary thyroid carcinoma patients (25%) with an undet ectable calcitonin level, in 5 of 7 phaeochromocytoma patients with increas ed urinary catecholamine and metabolite excretion, and in 2 of 3 patients w ith a non-functioning phaeochromocytoma. During follow-up, the course of ch romogranin A was found to parallel that of tumour burden and/or 24-hour uri nary metanephrine in 5 phaeochromocytoma patients. We conclude that chromog ranin A measurement is not recommended for the diagnosis of medullary thyro id carcinoma patients. It may be useful in patients with functioning and no n-functioning phaeochromocytomas as a follow-up marker. In neuroendocrine t umour patients with elevated calcitonin secretion, the serum cr-subunit of glycoprotein hormone measurement may help differentiate medullary thyroid c arcinoma or phaeochromocytoma patients from other endodermal-derived neuroe ndocrine tumour patients in whom it is frequently elevated. (C) 2001 Cancer Research Campaign http://www.bjcancer.com.