Abstract PD2-4: Association between body mass index change during neoadjuvant chemotherapy and pathologic complete response and overall survival in patients with inflammatory breast cancer or locally advanced non-inflammatory breast cancer

Abstract

Abstract Background: The rate of pathologic complete response (pCR) to neoadjuvant systemic treatment (NST) of patients with a body mass index (BMI) of ≥25 has been reported to be significantly lower than that of patients with a BMI <25. However, only patients with a BMI of ≥30 have been found to have worse overall survival (OS) than patients with a BMI <25. Several studies have shown that an increasing body weight after surgery is a poor prognostic factor for OS. Whether a higher BMI after NST and before surgery truly predicts response to chemotherapy or outcomes remains unclear. We hypothesized that higher BMI will be associated with lower rates of pCR and long-term clinical outcomes. The purpose of this study was to determine whether a change in BMI from baseline to after NST and definitive surgery affects pCR and OS in patients with inflammatory breast cancer (IBC) or locally advanced non-IBC. Material and Methods: We retrospectively reviewed the medical records of 263 patients with primary IBC and 865 patients with stage III non-IBC who underwent standard NST consisting of anthracyclines and/or taxanes with or without concurrent trastuzumab followed by definitive surgery at our institution between November 1, 2006, and December 31, 2012. Results: The median follow-up time for survivors was 19.8 months (0.1-69.9 months). One hundred forty-five (55.1%) IBC and 566 (65.7%) non-IBC were hormone receptor-positive and 91 (34.6%) IBC and 198 (22.9%) non-IBC were human epidermal growth factor receptors (HER2)-positive. One hundred forty-four (54.8%) IBC and 446 (51.9%) non-IBC were postmenopausal. Of the 1128 patients included in the study, 223 (19.8%) achieved pCR, including 42 (16.0%) IBC and 181 (20.9%) non-IBC. The median change in BMI during NST of the patients who achieved pCR (0.1) was significantly higher than that of the patients who did not achieve pCR (-0.1; p = 0.04). The pCR rate of the patients whose BMIs had positive change post NST (23.2%) was higher than that of the patients whose BMIs were lower after NST (18.2%), but this difference was not significant (p = 0.054). Multivariate analysis did not reveal positive change in BMI post NST to be a significant predictor of pCR. Univariate analysis with the log-rank test revealed that higher BMI change from pre NST as a categorical variable (BMI change >0 vs. ≤0) predicted increased OS in all patients (p = 0.005) and in IBC patients (p<0.001). After adjust for other clinical variables, none of the BMI-related measures (i.e., baseline BMI, BMI at surgery, and BMI change during NST) predicted OS. Although univariate analysis revealed that BMI change as a continuous variable predicted OS in IBC patients (p = 0.031), after adjust for other clinical variables BMI change no longer predicted OS. None of the BMI measures as continuous or categorical variables predicted recurrence-free survival. Conclusion: In patients with stage III breast cancer, a higher BMI after NST than at baseline does not predict lower pCR rate or decreased survival after adjust for other clinical variables. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD2-4.