Medullary thyroid carcinoma: prognosis of familial versus nonfamilial disease and the role of radiotherapy.

A retrospective study of 202 patients with medullary thyroid carcinoma (MTC) diagnosed between 1943 and 1987 was done to compare the prognosis of patients with sporadic disease and those with the familial form of multiple endocrine neoplasia type II (MEN-II) and to study the effect of radiotherapy. The relationship between serum calcitonin (iCT), carcinoembryonic antigen (CEA), and calcitonin gene-related peptide (CGRP) to the extent of disease and prognosis was also studied. Patients with MEN-II had significantly longer survival rates than did patients with the sporadic variety (P less than 0.005), but most patients with sporadic disease were older and had more advanced disease. No differences in survival rates were found when patients from these two groups were matched for age and extent of disease (P greater than 0.7). When patients who received radiotherapy were matched for age, extent of disease, and surgery with patients who had had no radiotherapy, the latter group was found to live significantly longer (P less than 0.05). Our studies suggested (1) that the apparently poor prognosis of patients with sporadic MTC may be related to the patients' older age at detection rather than to inherent differences in the two forms of disease, (2) radiotherapy has little effect on MTC, (3) calcitonin gene-related peptide measurement was not helpful in determining the extent of disease or prognosis, (4) patients with liver metastasis had the highest iCT levels, (5) patients with bone metastasis had the highest CEA levels, and (6) patients with diarrhea had poor prognosis and had high iCT levels.