Treatment of medullary carcinoma of the thyroid. Value of calcitonin as tumour marker.

Changes in immunoreactive serum calcitonin were measured in 11 patients with medullary carcinoma of the thyroid, before and after surgery, external high-voltage irradiation, 131I therapy, and chemotherapy. Measurement of serum calcitonin concentration was found to be a useful method for evaluating tumour mass and function during treatment. Contrary to previous reports, treatment with 131I resulted in a positive effect on serum calcitonin and diarrhoea, and in one patient with bone metastases these disappeared. No response was found following chemotherapeutic regimes. Calcitonin was found to be more sentitive than palpation, radiography, and scintigraphy for determining the amount of tumour tissue, but a definite correlation between this amount and the concentration of serum calcitonin was not found.