Prolactin and colorectal cancer: is there a connection?

The purpose of this study was to confirm the reported incidence of hyperprolactinemia in colorectal cancer and to find further evidence for an ectopic prolactin production by the tumor.

Thirty two consecutive patients with an adenocarcinoma of the colon (n = 17) or the rectum (n = 15) were included. Preoperative serum prolactin concentrations were determined and correlated with CEA concentrations and tumor stages. To exclude an ectopic production by the colon cancer, prolactin concentrations were determined during the operation, in the peripheral blood and in the efferent venous drainage area of the tumor. After resection, immunohistochemical staining for prolactin was made in all resected tumors.

In all except two patients with a rectal cancer, preoperative plasma prolactin concentrations were normal. Peroperative serum concentrations of prolactin were high in all patients. No significant gradient was found between the peripheral venous concentration and the local venous concentration in the drainage area of the tumor. Immunohistochemical staining for prolactin was positive in only one rectal cancer. Finally, no correlation was found between plasma prolactin concentrations and tumor stages or CEA concentrations.

Our results do not support the hypothesis of an ectopic prolactin production by colon adenocarcinoma. Only in a subgroup of rectal cancers, an ectopic prolactin production remains probable. At present, prolactin cannot be recommended as a tumor marker in colorectal cancer.