Serum calcitonin after pentagastrin stimulation in patients with bronchogenic and breast cancer compared to that in patients with medullary thyroid carcinoma.

Serum immunoreactive calcitonin (iCT) was measured in the peripheral blood of 29 normocalcemic patients with bronchogenic carcinoma of various pathological types and nine patients with breast cancer before and after pentagastrin stimulation. These results were compared to those found in 22 normal subjects and 30 patients with histologically proven medullary carcinoma of the thyroid. Our results revealed that 1) serum iCT levels may be abnormally high in all pathological types of bronchogenic carcinoma and in patients with breat cancer; 2) the basal level of serum iCT may be normal, but it is abnormally high after pentagastrin stimulation; 3) the increment rise of iCT after pentagastrin stimulation in the bronchogenic and breast cancer patients was significantly less than that seen in patients with medullary carcinoma of the thyroid (P less than 0.001).