Abstract 6492: Body mass index characterization of patients undergoing neoadjuvant chemotherapy for breast cancer: Correlation with survival

Abstract Background: The significance of body mass index (BMI) on treatment outcomes of neoadjuvant chemotherapy for breast cancer and impact on overall survival is not well understood. We reviewed our single institution data on BMI of patients who underwent curative intent neoadjuvant chemotherapy for breast cancer. Methods: An IRB-approved retrospective review identified demographics (including BMI), disease presentation, response to treatment, and outcomes. ER and PR status were categorized as low positive (1-9%), positive (≥ 10%) and negative. Treatment response was noted as percent residual cellularity(complete 0%, almost complete < 10%, good 10-30%, moderate >30-80% and poor >80%) in the surgical specimen. Cox proportional hazards models were used to assess relationships with overall survival. Results: 372 patients underwent curative-intent from 2005-2020; mean age was 51.0 years (SD=11.8); mean BMI was 28.6 (SD=6.3). Median follow-up was 4.3 years. There are significant differences in BMI among racial groups: American Indian (mean 31, SD 6.35), black (mean 30.1, SD 6.89), white (mean 28.3, SD 6.11) (p=0.001). There are significant differences in BMI between Hispanic and non-Hispanic patients: Hispanic (mean 29.6, SD 6.07), non-Hispanic (mean 27.5, SD 6.44), (p=0.001). Hormone receptor status (ER, PR, HER2 status) was not significantly associated with BMI, nor was treatment response either as complete pathologic response (p=0.52) or percent residual cellularity (p=0.98). BMI was not significantly associated in tumor shrinkage noted by changes in T stage or N stage categorizations from pre- to post-NAC. BMI was significantly associated with overall survival through interactions with ER status (p=0.01), and residual percent cellularity (p=0.02). ER- vs. ER+ risk was higher for those with low (HR, 95% CI=7.87, 2.60-23.8 at BMI=20) and moderate (HR, 95% CI=3.25, 1.68-6.33 at BMI=27.5). A five-point higher BMI was associated with a 1.6-fold higher mortality risk for those with complete percent residual cellularity (95% CI: 1.1-2.4), but this risk differential was not observed for those with good, moderate, or poor residual percent residual cellularity. Conclusions: In our study, BMI was significantly associated with race and Hispanic ethnicity. Although there were no significant association of BMI with treatment response to neoadjuvant chemotherapy, there appears to be a significant relationship between BMI and overall patient survival, through its interactions with other prognostic factors. Future research efforts should focus on exploring reductions in BMI through modifications of diet and exercise in improving survival of breast cancer patients, particularly those with higher risk tumors. Citation Format: Sangeetha Prabhakaran, Vernon S. Pankratz, Christopher F. McNicoll, Jacklyn M. Nemunaitis, Nadja Falk, Jain Zhou. Body mass index characterization of patients undergoing neoadjuvant chemotherapy for breast cancer: Correlation with survival. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6492.