Abstract P1-12-01: Preoperative Endocrine Therapy with Tamoxifen and Goserelin Acetate for Hormone Receptor-Positive Premenopausal Patients

Abstract

Abstract Background: Clinical trials have consistently shown that the response rates of hormone receptor-positive breast cancer patients to neoadjuvant chemotherapy are low. Preoperative endocrine therapy has therefore become a logical alternative for such patients. Several researchers have reported favorable response rates in postmenopausal women. However, the effectiveness of preoperative endocrine therapy for premenopausal women remains unknown. The aim of this study was to evaluate the potential benefits of preoperative endocrine therapy for premenopausal women. Materials and methods: Forty premenopausal patients with operable estrogen receptor (ER)-positive breast cancer were consecutively treated with neoadjuvant therapy with tamoxifen and Goserelin acetate for 3 months. The patients eligible for this study included clinically node-negative patients with tumors that were less than 2 cm in diameter and negative for human epidermal growth factor receptor 2 (HER2). All the patients were clinically evaluated using ultrasonograpy before and after the endocrine therapy. Further, core-needle biopsy specimens obtained before administration of the endocrine therapy and surgical specimens were pathologically evaluated for ER, progesterone receptor (PgR), HER2, p53, and Ki67 expressions. This study was approved by our institutional IRB. Results: The patients included in this study were 30-52 years old (median age, 43 years). The size of the tumor was 0.9-2.0 cm (median, 1.5 cm). The clinical response rate was 20% (8/40) and disease progression was not observed. In the case of 39 of the 40 patients, grade 0 or grade 1 pathological response was observed. Clinical responses were not correlated with pathological responses. The ER expression level before the endocrine therapy differed from that after the therapy in the case of 8% (2/40) of the patients (increased in 4% and decreased in 4%). Further, PgR expression was altered in the case of 50% (20/40) of the patients (increased in 8% and decreased in 42%). Moreover, Ki67 expression was decreased in 90% (36/40) of the patients after the endocrine therapy. Conclusions: This is the first report on neoadjuvant endocrine therapy for premenopausal patients. Disease progression 3 months after the endocrine therapy was not observed. Because the expressions of Ki67 and PgR decreased, these molecules might be candidate markers of endocrine responsiveness in premenopausal patients. To confirm this assumption, further evaluations involving tumors of a larger size, longer observational period, and more number of eligible patients are planned to be conducted. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-12-01.