[Pathophysiology of hyperprolactinemia in breast cancer]

To characterize the prolactin secretion in human breast cancer, plasma prolactin levels were measured in 514 patients with breast cancer in long term follow-up studies. In hyperprolactinemic patients suppression and stimulation tests were performed and the 24-h secretion profile was recorded. Tissue extracts and sera of hyperprolactinemic breast cancer patients were incubated with cultured pituitary cells in vitro to detect a prolactin releasing activity in these specimens. 44% of breast cancer patients developed hyperprolactinemia in the course of the disease. In 35% of measurements hyperprolactinemia was induced by non tumor related causes, e.g. prolactin-stimulating drugs, surgery, uremia, prolactinoma. Excluding such influences on the prolactin level, hyperprolactinemia over 1,000 mU/l was almost only found in patients with progressive metastatic disease. In these patients hyperprolactinemia was associated with tumor load, but not correlated to BSR, CEA or prognostic factors. Hyperprolactinemia in breast cancer was not of paraneoplastic origin. No prolactin-releasing activity was detected in tumor tissue and sera of hyperprolactinemic breast cancer patients.