Postprandial levels of prolactin and gut hormones in breast cancer patients: association with stage of disease, but not dietary fat.

Previous studies of the relationship between dietary fat and breast cancer have produced conflicting results and have provided no definitive evidence of a mechanistic link between fat and breast tumorigenesis. We conducted a study to compare postprandial levels of prolactin (Prl), a hormone suspected of promoting the growth of some human breast cancer, and several gut hormones, i.e., gastrin (Gs), vasoactive intestinal polypeptide (VIP), neurotensin (Nt), and cholecystokinin (CCK), following high- and low-fat isocaloric test meals. Data were obtained in the posttreatment period from 13 patients with breast cancer (nine stage I and four stage II), who were disease free clinically, and nine healthy controls. Subjects admitted to the research unit on 2 days were given the high-fat meal on day 1 and the low-fat meal on day 2. Blood samples were drawn before (i.e., fasting) and after test meal consumption. All hormone analyses were performed by radioimmunoassay. Results indicated a significant rise in postprandial Prl levels for stage II patients, but not for stage I patients or the controls. Postprandial Gs levels were also elevated, whereas VIP levels were markedly reduced in patients versus controls; these differences were most marked in stage II patients. No significant intergroup differences were noted in postprandial levels of Nt and CCK. Hormone levels of patients and controls did not differ between the test meal situations, which indicated that some other component of the test meals might have been responsible for altered Prl and Gs levels. The differences observed between the stage I and II patients indicated that diet may influence the aggressiveness of tumor behavior and development through alterations in postprandial hormone release.