A direct LHRH-agonist action on cancer cells is unlikely to be the cause of response to LHRH-agonist treatment.

LHRH-Agonist therapy has been shown to have some effect in cancer treatment. Chronic administration of LHRH-agonists may lead to a decreased gonadal steroidogenesis. A direct anti-tumor action of LHRH-agonists has also been reported. We observed only a small direct inhibitory effect of the LHRH-agonist Buserelin at high concentrations on the proliferation of three human ovarian cancer cell lines, and on estrogen-stimulated proliferation of human breast cancer cells in vitro. Proliferation of rat prostate cancer cells was not inhibited by Buserelin. It is unlikely that a direct anti-tumor effect is the major mechanism of action of LHRH-agonists in cancer treatment.