Small cell carcinoma of the lung: relation of calcitonin to bone marrow metastases, parathormone and gastrin.

The relations of calcitonin concentrations to the presence of bone marrow metastases and to the concentrations of calcium, parathormone and gastrin in serum were investigated in 74 untreated patients with small cell carcinoma of the lung. Calcitonin concentrations were enhanced in two thirds of the patients, while serum calcium concentrations were normal in all. In 19 of 57 patients parathormone concentrations were slightly above the normal range, but the concentrations of parathormone and calcitonin were not correlated. Bone marrow metastases had no influence on the concentration of serum calcitonin. Finally, a small inverse correlation between the concentrations of gastrin and calcitonin in serum was observed. The results resemble those of the calcitonin-producing medullary carcinoma of the thyroid, supporting the suggestion of an ectopic source of hypercalcitoninemia in small cell carcinoma of the lung.