Increased serum calcitonin in patients with mammary carcinoma.

Serum calcitonin war within normal range in 11 patients with benign breast tumour. In cases with local malignant breast tumour increased calcitonin was found in 25 per cent (4/16), in cases with regional metastases in 40 per cent (2/5), and in cases with osteolytic bone metastases in 77 per cent (10/13). Two patients with osteosclerotic bone metastases had low calcitonin concentration. It is suggested that increased calcitonin in mammary carcinoma is a physiologic response to osteolytic bone metastases.