Background: The use of preoperative endocrine therapy for breast cancer has increased during the last decade. Although several studies have reported favorable response rates in postmenopausal women, its effectiveness in premenopausal women remains unknown. This study therefore aimed to evaluate the potential benefits of preoperative endocrine therapy in premenopausal women.
Methods: Fifty-three patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative invasive breast cancer were included in this study. Preoperative endocrine therapy with goserelin acetate and tamoxifen was administered for 3 months. Clinical evaluations were performed by ultrasonography before and after endocrine therapy. Pathological evaluations were performed using core biopsy and surgical specimens. Immunohistochemical evaluations of ER, progesterone receptor (PgR), HER2, and Ki-67 were performed before and after endocrine therapy.
Results: Partial response (PR) was observed in 23 % (12/53) and progressive disease (PD) in 2 % (2/53) of patients. Significant suppression of Ki-67 was observed following endocrine therapy in 90 % (47/52) of patients (P < 0.0001). Significant downregulation of PgR was observed after endocrine therapy (P = 0.0002), which tended to be correlated with clinical response (P = 0.058).
Conclusions: Three months of preoperative endocrine therapy with goserelin acetate and tamoxifen was safe and effective in premenopausal patients with invasive breast cancer, with a 23 % PR rate. Changes in PgR and Ki-67 expression might be promising markers for endocrine responsiveness.