Change in Estradiol Levels among Premenopausal Patients with Breast Cancer Treated Using Leuprolide Acetate 11.25 Milligrams 3-Month Depot and Tamoxifen

The combination of luteinizing hormone-releasing hormone analogs (LHRHa) with tamoxifen is used as a standard postoperative adjuvant therapy in patients with hormone receptor-positive/premenopausal breast cancer. Long-acting LHRHa formulations offer advantages in terms of patient convenience. However, data on the effectiveness of the 3-month (3M) acting formulation are still insufficient. This study was performed on patients who received the 3M LHRHa after surgery. The serum estradiol (E2) and follicle-stimulating hormone levels were measured before surgery, and periodically after surgery. In total, 318 patients were included in the study and analyzed. The mean E2 level before surgery was 63.7 pg/mL, while the mean E2 level during the administration of 3M LHRHa was 4.9 pg/mL. None of the patients were menstruating and had E2 values above 30.0 pg/mL. It is thought that the 3M LHRHa formulation can suppress the ovarian function effectively and be safely used to improve compliance.