Purpose: To evaluate the endocrinological and clinical activity of a new slow-release formulation of leuprolide acetate in breast cancer patients.
Methods: A total of 50 pre- or perimenopausal patients with early- or late-stage breast cancer who were candidates for endocrine treatment were included in the study and randomly allocated to receive either 3.75 mg of leuprolide acetate every month or 11.25 mg of leuprolide acetate every 3 months. Patients were treated until disease recurrence or progression or for a maximum of 24 months. Treatment outcome, side effects, and serum levels of gonadotrophins, estradiol, progesterone, and delta4-androstenedione were analyzed at different time points.
Results: In all, 23 patients were allocated to the monthly formulation and 27, to the 3-monthly formulation. The median time on treatment was comparable. There was no evidence of any difference in clinical outcome or drug-induced side effects, hot flushes being recorded in about 50% of patients in both groups. Altogether, 35 patients were actively menstruating at the beginning of treatment; all of them became amenorrhoic after 3 months and remained so until treatment with leuprolide was continued, irrespective of the allocated treatment. All endocrine parameters, particularly estradiol levels, were suppressed to a similar extent.
Conclusions: The present results indicate that the two formulations exert a comparable estrogen-suppressive effect and warrant further study of the 3-monthly formulation of leuprolide acetate in breast cancer patients.