Mastectomy stimulates prolactin release in breast cancer patients.

Hyperprolactinaemia has been described to occur after mastectomy in breast cancer patients, but whether it may be the result of surgery or breast cancer is particularly unknown. Plasma prolactin levels were measured in 51 patients one day before, and 1, 7, 30, and 180 days after mastectomy (23 primary breast cancer patients), tumourectomy (10 patients with benign or malignant breast lesions), and cholecystectomy (18 patients with cholelithiasis). Elevated prolactin levels were found on the 7th and 30th postoperative day in mastectomized and laparotomized patients, but not in patients who underwent tumourectomy of benign or malignant breast lesions (p less than 0.01). The prolactin levels were in the normal range one day before and again 180 days after surgery in all patients. We conclude, therefore, that postoperative hyperprolactinaemia in breast cancer patients is a result of surgery rather than the disease.