Abstract P6-09-38: Interaction between body mass index and hormone receptor status as a prognostic factor in node-positive breast cancer

Abstract Purpose: The aim of this study was to investigate the interaction between BMI at breast cancer diagnosis and the various factors including hormone-receptor, menopausal and nodal status, and to find a specific subgroup where BMI has an effect on breast cancer prognosis. Methods: We retrospectively analyzed the data of 8,763 non-metastatic invasive breast cancer patients from the Asan Medical Center's research database. Overall survival (OS) and breast cancer-specific survival (BCSS) among BMI groups were compared using the Kaplan-Meier method and Cox proportional hazard model with interaction term. Results: Only in node-positive breast cancer, there was a significant interaction between obesity (BMI ≥ 30.0 kg/m2) at diagnosis and positive hormone receptor which showed worse overall survival (OS) and breast cancer specific survival (BCSS) than normal weight patients (adjusted hazard ratio [HR] = 1.65, 95% confidence interval [CI] = 1.01 to 2.69 and HR = 1.90, 95% CI = 1.15 to 3.15, respectively). Underweight (BMI<18.50 kg/m2) which interacted with negative hormone receptor status in node-positive breast cancer was associated with decreased OS (HR = 2.01, 95% CI = 1.02 to 3.98) and BCSS (HR = 2.15, 95% CI = 1.08 to 4.26). There was no significant interaction between BMI and hormone receptor status in node-negative setting and BMI did not interact with menopausal status in any population. Conclusions: BMI interacts with hormone receptor status in node positive setting, thereby playing a role in the breast cancer prognosis. Citation Format: Chung IY, Lee JW, Lee JS, Park YR, Lee Y, Lee SB, Kim HJ, Ko BS, Son BH, Ahn SH. Interaction between body mass index and hormone receptor status as a prognostic factor in node-positive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-38.