Abstract P1-06-02: The effect of race on pathologic complete response rates and overall survival in patients with triple negative breast cancer

Abstract Introduction: Despite the recent overall improvement in survival for patients with breast cancer, racial disparities in outcomes persist. While studies have demonstrated that socioeconomic factors and access to treatment play a role, differences in tumor biology may also contribute. Black women are significantly more likely to develop triple negative breast cancer (TNBC), the deadliest of the breast cancer subtypes, with more TNBC patients progressing to incurable, metastatic disease than patients with any other breast cancer subtype. Studies have demonstrated that TNBC patients who achieve a pathologic complete response (pCR), defined as no residual invasive cancer in the breast or lymph nodes after neoadjuvant chemotherapy (NAC), have improved survival. We hypothesize that rates of pCR and overall survival (OS) in patients with TNBC may differ by race/ethnicity, which may account in part for the disparities in outcomes observed. Methods: Adult female patients with stage I-III TNBC diagnosed in 2010-2019 who received NAC followed by surgery were identified from the National Cancer Database (NCDB). Race/ethnicity was defined as Hispanic (H), Non-Hispanic White (NHW), Non-Hispanic Black (NHB), Non-Hispanic Asian (NHA), and Non-Hispanic Other (NHO). pCR was defined as no invasive cancer in either the breast or axilla (ypT0/is,N0) at surgery. Logistic regression was used to estimate the association of race/ethnicity with achievement of pCR after adjustment for covariates. Unadjusted OS was estimated using the Kaplan-Meier method, and the log-rank test was used to compare groups. Cox Proportional Hazards models were used to estimate the association of race/ethnicity and achievement of pCR with OS after adjustment for covariates. Additional interaction and subgroup analyses were also conducted. Results: Of the 40,890 patients identified, 29.8% (n=12,173) demonstrated pCR after NAC. The unadjusted 5-year OS rates for those who achieved pCR were significantly higher compared to patients with no pCR (0.917, 95% CI 0.911-0.923 vs 0.667, 95% CI 0.661-0.673, log-rank p< 0.001). Hispanic patients were more likely to achieve pCR (OR 1.19, 95% CI 1.08-1.31, p=0.001), and NHB patients were less likely to achieve pCR (OR 0.89, 95% CI 0.83-0.95, p=0.001) compared to NHW, even after adjustment. Unadjusted OS was also notably lower for NHB patients compared to every other race group (5-year OS rate: NHB 0.709 vs NHW 0.746 vs NHO 0.771 vs H 0.772 vs NHA 0.816, log-rank p< 0.001); however, this difference did not persist after adjustment for patient and disease factors, including achievement of pCR. Interval from diagnosis to start of chemotherapy (OR 0.95, 95% CI 0.94-0.96, p< 0.001) and duration after chemotherapy start to surgery (OR 1.02, 95% CI 1.02-1.03, p< 0.001) were associated with the odds of achieving pCR. Overall, the effect of achieving pCR on OS did not differ by race/ethnicity (interaction p=0.10). Discussion: Achieving pCR after NAC in patients with TNBC is associated with a significant improvement in OS. Yet, rates of pCR appear to differ based on race/ethnicity, with NHB patients demonstrating significantly lower rates of pCR than NHW patients, which may contribute to the disparities in survival outcomes observed. In addition to addressing socioeconomic factors and access to treatment, further research examining whether biological differences exist based on race that influence response of TNBC to current standard therapies is essential for improving survival outcomes for this disproportionately affected patient population. Citation Format: Hannah E. Woriax, Samantha M. Thomas, Jennifer K. Plichta, Laura H. Rosenberger, Astrid Botty van de bruele, Akiko Chiba, Gayle DiLalla, Carolyn Menendez, E Shelley Hwang, Maggie L. DiNome. The effect of race on pathologic complete response rates and overall survival in patients with triple negative breast cancer [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 P1-06-02.