Effectiveness of a 6-Month 22.5-mg Leuprolide Acetate Depot Formulation With Tamoxifen for Postoperative Premenopausal Estrogen Suppression in Hormone Receptor-Positive Breast Cancer

Abstract

BackgroundIn patients with hormone receptor-positive (HR+)/premenopausal breast cancer, luteinizing hormone-releasing hormone analogs (LHRHas) are used as standard endocrine treatment. Based on previous clinical studies, 1-month formulations are recommended in most breast cancer treatment guidelines, but long-acting formulations facilitate reductions in side effects and patient discomfort caused by frequent administration. However, few efficacy studies have been conducted on 6-month formulations. Therefore, this study aimed to evaluate the efficacy of 6-month formulations of LHRHas.MethodsThis retrospective study was conducted from January 2018 to December 2019 and involved premenopausal patients with HR+ breast cancer administered 6-month LHRHas as adjuvant treatment after surgery, and those previously administered chemotherapy or other LHRHa types were excluded. Patients’ estradiol (E2) and follicle-stimulating hormone (FSH) levels were measured before surgery, and their E2 levels were also measured at 3, 6, 12, 18, and 24 months at periodic postsurgical examinations.ResultsA total of 228 patients were included, and the median patient age was 44 (range, 25–54) years. The mean serum E2 and FSH levels before surgery were 69.7 (range, 4–683) pg/mL and 7.3 (range, 0.4–88.9) mIU/mL, respectively, whereas the mean serum E2 level monitored at intervals during the 6-month LHRHa administration was 5.5 (range, 4.0–52) pg/mL. No women menstruated during the follow-up period after the LHRHas administration, and the E2 levels were less than 30 pg/mL in all patients except one.ConclusionsThe 6-month LHRHa formulation adequately suppressed ovarian function in premenopausal patients with HR+ breast cancer. This indicates that long-acting LHRHas can be effectively used for patient convenience and that there is high compliance with long-term use.