The impact of obesity on triple negative breast cancer (TNBC) outcomes at a diverse academic cancer center.

Abstract

e12529 Background: Multiple studies have linked obesity (BMI ≥30 kg/m2) to poor outcomes from triple negative breast cancer (TNBC). To further explore the association between obesity and TNBC, we conducted a retrospective chart review at our institution to examine the association of race and obesity with disease free survival (DFS) and pathologic complete response (pCR) rates. Our institution is a unique setting in which to study this because of its large African-American (AA) pt population relative to other academic medical centers in the United States. Methods: A chart review of 247 early-stage TNBC pts treated from 2004- 2017 was conducted. All cases were retrieved from pathology archival reports. Of these 247 pts, 116 were treated with adjuvant chemotherapy and 131 were treated with neoadjuvant chemotherapy (NAT). Pts were categorized as obese (BMI = / > 30) and non-obese (BMI < 30), AA [n = 151], Caucasian [n = 84], other [n = 11], and missing [n = 1]. The association of race and BMI with pCR following NAT (for the NAT group), and the association of race and BMI with DFS (for all pts) was evaluated. Results: 50.3% of AA pts and 32% of Caucasians were obese. 43% of obese pts had node-positive disease at diagnosis, compared with 31% of non-obese pts. Among the node-positive TNBC pts, non-obese pts had a trend towards a longer DFS than obese pts with a HR 0.80 (95% CI 0.37 – 1.71) and a non-statistically significant p-value of 0.562. We evaluated pCR rates based on race and BMI. Among AA pts, 56.9% did not achieve pCR after NAT, and of these pts 44.4% were obese; 43.1% achieved pCR and of these 58.8% were obese (p = 0.206). Among Caucasian pts, 65% did not achieve pCR, and of these 43.3% were obese; of the 35% of Caucasian pts who achieved pCR, 31.25% were obese (p = 0.424). Among pts who eventually developed distant metastases, there was a strong trend towards shorter DFS in the obese group, with a HR 1.92 (95% CI 0.94-3.95) and a non-statistically significant p-value of 0.075. Conclusions: In this sizable population of TNBC pts at a racially diverse academic medical center, obesity was associated with a higher incidence of nodal involvement at diagnosis, and shorter interval of time to development of distant metastatic disease. Race was not found to impact pCR or DFS in a statistically significant way. This could have been related to small sample size (particularly in the NAT group), or because some socioeconomic variables often tied to poor outcomes among minority pts may have been minimized in this study. The association of obesity with node positivity at diagnosis and with shorter interval times for development of metastases highlights the importance of adopting initiatives to minimize obesity in oncology practices and in the primary care setting. Improving access to healthy food and to safe spaces for exercise will help to prevent obesity, and thus may reduce the risk of developing TNBC and improve breast cancer outcomes among all pts, regardless of race.