Plasma and tumor prolactin in colorectal cancer patients.

Fifteen consecutive patients with recently diagnosed colorectal cancer were studied for plasma and tumor tissue prolactin content. In eight patients (four men and four postmenopausal females), preoperative high plasmatic prolactin was found (mean 1553 nmol; range 516-3677 nmol). In three of them, prolactin was also present in the tumor cells. All plasma prolactin levels returned to normal after tumor resection and remained so during a three-month follow-up. The tumor stage by Duke distribution was similar for both high and normal plasmatic prolactin patients. The role of prolactin in the pathogenesis of colorectal cancer, and as a marker of the tumor, remains to be established. This is the first time that prolactin has been detected in human colon cancer.