Abstract P3-05-53: IMPACT OF THE BODY MASS INDEX (BMI) ON THE SURVIVAL OF BREAST CANCER WOMEN WHO ACHIEVED A COMPLETE PATHOLOGICAL RESPONSE (pCR) AFTER NEOADJUVANT CHEMOTHERAPY (NACT) IN BRAZIL

Introduction Breast cancer (BC) it is highly prevalent in the world with a significant mortality rate despite advances in systemic therapies. Obesity increases the risk of this cancer specially in post-menopause women and may even affect the prognosis at all ages. Objective To evaluate the impact of BMI on overall (OS) and disease free interval (DFI) of Brazilian women with BC undergoing NACT and who achieved pCR. Methods This is a retrospective study that included patients with confirmed breast cancer clinical stage I to III, age more than 18 years old and complete records that were submitted to NACT. These patients were divided in four groups based on their BMI by the World Health Organization definition BMI < 18,5 kg/m2: underweight; BMI 18,5 to < 25 kg/m2: healthy weight; BMI 25 a < 30 kg/m2: overweight; BMI ≥30kg/m2: obesity. pCR was defined as absent of invasive tumor in the breast or axilla. Student t test or chi-square test were used to analyze the association of each variable between groups with and without pCR. Univariate and multivariate analyzes were used to calculate odds ratios (OR) and 95% of confidence intervals (CI) of the independent variables BMI, age, clinical stage, immunohistochemistry and correlated with pCR (p value < 0.05 was assumed as statistically significant). The study was approved by local ethics committee. Results A total of 1.481 patients from a single reference center between January 2011 to May 2020 were included. The mean age was 50 years and mean BMI was 28,08 (SD 5,59). Most of the patients presented clinical stage III (67,3%) at diagnosis. Invasive carcinoma nonspecial type was the most frequent (95,11%). After NACT 1.138 (76.84%) still had invasive disease and only 343 (23.16%) had pCR. BMI ratio was 1.6% underweight, 30.5% healthy weight, 34.9% overweight and 33.0% obese. Regarding survival analyses, there was no statistical significance for the different BMI categories for both OS (p=0.43) and DFS (p=0.7) and no statistical significance when evaluated pCR and BMI OS (p=0.26) and DFS (p=0.22). OS was estimated for three groups (healthy weigh: 109 months, overweight: 105 months, obese: 79 months). For patients with underweight, the median OS was not reached. The 5-year OS rate in Brazil, according to this study, was 85.4%. Of these 1,481 women, 387 relapsed after surgery (22 cases: local relapse; 355: systemic relapse; 10: both relapses). Only the underweight reached the median (58 months) but this group is very small, and the other categories still have immature data because the median was not reached to define DFS. The association of the most aggressive subtypes of cancer as predictors of pCR was statistically significant (Luminal B: p=0.019; HER 2: p< 0.001; Triple negative: p< 0.001, in relation to Luminal A). There wasn’t any statistical significance for the different BMI categories. Conclusion This study did not show interference of BMI on OS and/or DFS in Brazilian women with BC undergoing NAC. Few patients reached pCR (23.16%) probably due to the advanced initial stage. On the other hand, pCR was much more frequent in the more aggressive subtypes (Triple negative, HER 2 and Luminal B). Obesity as an independent chronic condition and despite not having an impact on survival in these analyses, most women were overweight or obese (72.85%), showing the frequency of obesity in Brazilian women, which should be understood as a public health problem in the country. In addition, following these women for 10 years can help to understand better the real impact of obesity in breast cancer survival. Table 1. Percentual of breast cancer in different clinical stages. Table 2. Logistic regression considering pCR as an outcome. Citation Format: FERNANDA GRACE BAUk RICHTER, ANDRE MATTAR, Marcelo Antonini, REGINALDO G. COELHO LOPES, Jorge Y. Shida, Luis Henrique Gebrim, Juliana Monte Real. IMPACT OF THE BODY MASS INDEX (BMI) ON THE SURVIVAL OF BREAST CANCER WOMEN WHO ACHIEVED A COMPLETE PATHOLOGICAL RESPONSE (pCR) AFTER NEOADJUVANT CHEMOTHERAPY (NACT) IN BRAZIL [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-53.