Circulating levels of prolactin in human breast cancer.

Serum prolactin concentrations were measured by radioimmunoassays in 98 patients with established carcinoma of breast, 12 patients with cystic mastitis and 10 patients with gynaecomastia and compared with that of age matched normal control women. The serum prolactin levels in the patients with breast cancer, gynaecomastia or cystic mastitis were observed to be similar to that in normal women. It was interesting to note that the levels of prolactin in the luteal phase of the cycle were higher than that in the early follicular phase in normal women.