Ondansetron does not stimulate prolactin release in breast cancer patients

Prolactin (PRL) may be a tumor growth factor, mainly for breast cancer. The antidopaminergic drugs commonly used in the treatment of chemotherapy-induced vomiting stimulate PRL release, and this finding could represent a potentially negative biologic event for cancer patients. This study was performed to analyze PRL response to the serotonin-type 3 receptor antagonist ondansetron, a new active drug in the treatment of vomiting due to chemotherapy, in cancer patients.

The study included 8 premenopausal breast cancer patients undergoing adjuvant chemotherapy. Ondansetron was given intravenously at a dose of 8 mg, and venous blood samples were drawn at 0, 20, 60 and 120 min. The result were compared to those seen in 10 breast cancer patients treated with metoclopramide (10 mg. i.v.).

PRL mean levels significantly increased in response to metoclopramide. In contrast, no significant changes in PRL mean values occurred after ondansetron injection.

The study showed that ondansetron, whose efficacy in the treatment of chemotherapy-induced vomiting is well known, does not stimulate the tumor growth factor PRL in cancer patients, in contrast the the action of the most commonly used antidopaminergic drugs.