Obesity and survival in the neoadjuvant breast cancer setting: Role of tumor subtype and race.

Abstract

e12136 Background: Obesity may adversely influence survival in breast cancer; however, studies are conflicting and limited in the neoadjuvant setting. Results may also vary by tumor subtype and race/ethnicity. Our study seeks to examine associations between obesity and survival in women receiving neoadjuvant chemotherapy (NAC) and the role of tumor subtype and race/ethnicity. Methods: In a retrospective review of women with operable invasive breast cancer administered Adriamycin/Taxane-based NAC at a single intuition from 2004-2016, we identified n = 273 women with completed BMI data at diagnosis. Obesity was defined as body mass index (BMI) > = 30. We assessed associations between obesity and progression-free survival (PFS), using STEEP criteria, and overall survival (OS), using all-cause mortality, both overall and stratified by tumor subtype in three groups: Hormone Receptor Positive (HR+)/HER2- (n = 135), HER2+ regardless of hormonal status (n = 94), and Triple Negative Breast Cancer (TNBC) (n = 44), examining race/ethnicity (Non-Hispanic White, Black and Hispanic) in each subtype. Results: There were 60 events and 33 deaths observed. Overall, obesity was associated with worse PFS (HR1.71 95% CI 1.03-2.85, p = 0.04) and a trend towards worse OS (HR 1.70 95% CI 0.86-3.37, p = 0.13). In HR+/HER2- disease, there was an interaction between obesity and hormonal therapy. In those receiving only tamoxifen (n = 35), obesity was associated with worse PFS (HR 2.96 95% CI 1.02-8.6, p = 0.047) and OS (HR 14.3 95% CI 1.67-123.1, p = 0.015). In those receiving an aromatase inhibitor (AI) (n = 96), there was no association between obesity and survival, p > 0.05. In TNBC, obesity was associated with worse PFS (HR 2.62 95% CI 1.03-6.66, p = 0.043) and OS (HR 3.00 95% CI 0.95-9.51, p = 0.062). In HER2+ disease, obesity was associated with worse PFS (HR 3.37 95% CI 0.97-11.72, p = 0.056) but not OS (HR 1.35 95% CI 0.22-8.19, p = 0.75). Race/ethnicity was not significantly associated with survival in any tumor subtype, and there were no interactions between race/ethnicity and obesity with survival. Conclusions: Obesity negatively impacts survival in all tumor subtypes, including TNBC, and may be influenced by hormonal therapy class in HR+/HER2- disease.