Association of response to neoadjuvant chemotherapy (NAC) in premenopausal patients with hormone receptor-positive early breast cancer with chemotherapy-induced ovarian function suppression by NAC.

e11017 Background: The purpose of this study is to assess the additive endocrine effect by chemotherapy-induced ovarian function suppression (CIOS) for premenopausal women with early breast cancer in neoadjuvant chemotherapy (NAC). Methods: We retrospectively compared the clinical efficacy to NAC between premenopausal and postmenopausal patients with early breast cancer to evaluate the endocrine effect by CIOS. One-hundred twenty two patients received NAC with anthracycline-containing regimen and/or taxane in Kumamoto University Hospital between April 2004 and March 2011. Results: Objective response rate by NAC in premenopausal ER-positive/HER2-negative patients is greater than that in postmenopausal ER-/HER2+ patients (premenopausal 93% vs. postmenopausal 63%, p=0.0121). Reduction rate of primary tumor by NAC on imaging studies in premenopausal ER+/HER2- patients is greater than that in postmenopausal ER-/HER2+ patients (premenopausal 54% vs. postmenopausal 40%, p=0.006). However, no significant difference in response rate between in premenopausal patients with other subtypes and postmenopausal patients with those was found (ER+/HER2+; premenopausal 50% vs. postmenopausal 48%, ER-/HER2+; premenopausal 43% vs. postmenopausal 77%, Triple-negative; premenopausal 86% vs. postmenopausal 65%). All of premenopausal women were suppressed ovarian function within two months after initiation of NAC. Expression levels of progesterone receptor on primary tumor in premenopausal ER+ cancer were significantly decreased after NAC compared with that in postmenopausal ER+ cancer (premenopausal -40.3% vs. postmenopausal +3.6%, p<0.001). Conclusions: These data suggests that CIOS by NAC contributes the additive effects through the endocrine fashion in premenopausal patients with ER+/HER2- breast cancer.