Abstract P6-15-08: Neoadjuvant chemotherapy vs neoadjuvant endocrine therapy in ER/PR positive HER-2 negative post-menopausal women with breast cancer, is one superior than other? A NCDB analysis

Background: Small prospective studies show comparable response rates (RR) and breast conservation rates (BCR) among neoadjuvant endocrine therapy (NET) and neoadjuvant chemotherapy (NCT) in post-menopausal hormone receptor (HR) positive breast cancer patients. Recently we reported statistically significant differences in utilization, trends, RR, BCR and overall survival (OS) outcomes in HR positive post-menopausal women from NCDB (2004-2014) at ASCO 2017 meeting. The absolute difference in OS calculated at 5 yrs for NCT vs NET was 10.9%. However, we were not able to exclude human epidermal growth factor receptor (HER-2) positive group due to the unavailability of information. Therefore, our results might have been skewed. Thus, here we report RR, BCR and OS outcomes in post-menopausal women with HR positive, HER-2 negative breast cancer using NCDB from 2010-2014 during which HER-2 status was recorded. Methods: We extracted data on HR positive, HER-2 negative breast cancer patients aged ≥ 50 without metastasisfrom the NCDB registry (2010-2014). RR and BCR between NET and NCT was assessed using univariate and multivariate analysis. OS was calculated using Kaplan Meier analysis with hazard ratio (HR) from cox regression model. We excluded patients who did not receive adjuvant endocrine therapy after NCT and patients who received adjuvant chemotherapy after NET as this could affect OS. Results: Out of 25,609 breast cancer patients reported in NCDB from 2010-2014, 19,988 women met our inclusion criteria. 5759 received NET and 14,229 received NCT. On multivariate analysis NET use was higher in academic centers [Odds ratio (OR) 1.327, 95% CI 1.222-1.440], patients with age>70 (OR 6.213, 95% CI 5.615-6.875)]. NET use was lower in black race (OR 0.774, 95% CI 0.679- 0.882), tumors with higher grade (OR 0.160, 95% CI 0.141-0.181), higher T stage (OR 0.352, 95% CI 0.314-0.395), higher N stage (OR 0.209, 95% CI 0.177-0.246) and private insurance (OR 0.65, 95% CI 0.525- 0.806), (all p Conclusions : Our analysis demonstrates higher response rate with NCT over NET even in HER-2 negative HR positive breast cancer. However, more patients underwent mastectomy in the NCT group despite high RR. Statistically significant improvement in OS was also seen with the use of NCT however the magnitude was less pronounced compared to our previous cohort which included HER-2 positive as well as negative patients. Limitations that should be considered in this registry based study are: differences in surgical technique, patient9s choice, duration and choices of adjuvant therapy. Citation Format: Basnet A, Wang D, Sivapiragasam A. Neoadjuvant chemotherapy vs neoadjuvant endocrine therapy in ER/PR positive HER-2 negative post-menopausal women with breast cancer, is one superior than other? A NCDB analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-15-08.