Lack of association between hyperprolactinemia and colon carcinoma.

Two recent studies reported that many patients with colorectal carcinoma have elevated serum prolactin (PRL) concentrations and have suggested ectopic PRL secretion as the cause. In the present study, serum PRL was minimally elevated in 16 of 116 colon cancer patients and 2 of 25 control subjects; medications or chemotherapy appeared to be responsible for the PRL elevations in 11 of 16 cancer patients. Serum PRL was not correlated with either plasma carcinoembryonic antigen or disease stage. Preoperative and postoperative serum PRL concentrations were similar in 26 evaluated patients. None of 19 colorectal tumors was positive for PRL staining by immunohistochemistry. Thus, we could not confirm previous reports of frequent hyperprolactinemia in patients with colorectal cancer; factors such as medications, anxiety, pain, and nausea may have raised serum PRL in these earlier studies. Serum PRL is not a useful marker for colon carcinoma, at least in patients in the United States.