Trends, patterns, and outcomes of neoadjuvant chemotherapy (NACT) use among patients with early invasive triple negative breast cancer (TNBC).

602 Background: TNBC is associated with clinically aggressive behavior and poorer survival outcomes. Among patients with TNBC, the use of NACT offers several advantages including improved outcomes among those who achieve a pathological complete response (pCR). We examined the patterns of NACT use, trends of pCR, and the association between pCR and overall survival (OS) in a large cohort of patients. Methods: Patients ≥18 years with stage I-III TNBC diagnosed between 2010-2020 who underwent surgery and received chemotherapy were identified in the National Cancer Database. Trends in NACT use and pCR were assessed using multivariable logistic regression and the Cochran-Armitage test for time trends. Multivariable logistic regression was used to evaluate the factors associated with pCR. The impact of pCR on OS was examined using a multivariable Cox proportional hazards model with propensity score (PS) adjustment and by PS matching (1:1 matching performed by exact year of diagnosis and clinical stage). Results: Of 133,437 patients with TNBC who received chemotherapy, 30.75% received NACT. The rate NACT receipt increased from 19% in 2010 to 44.7% in 2020 (p<0.001). Among patients with NACT, pCR rates increased from 19.8% in 2010 to 35.6% in 2020 (p<0.001). Patients treated with chemotherapy between 2014-2017 (aOR=1.89; 95% CI 1.84–1.95) or 2018-2020 (aOR= 2.89; 95% CI 2.79–2.99) were more likely to receive NACT than those treated in 2010-2013. Compared to non-Hispanic Whites, Black patients were less likely (aOR=0.86; 95% CI 0.83–0.89) to receive NACT. Among patients who received NACT, treatment receipt between 2014-2017 (aOR=1.41; 95% CI 1.33–1.50) or 2018-2020 (aOR= 1.86; 95% CI 1.76–1.98) was associated with higher odds of achieving pCR relative to treatment receipt between 2010-2013. Black patients were less likely (aOR=0.87; 95% CI 0.83–0.94) to achieve a pCR relative to White patients. Other factors associated with NACT receipt and pCR rates were age, cancer stage, comorbidity, type of insurance, income, and facility type. Among patients treated with NACT, pCR was associated with lower risk of death (aHR= 0.26; 95% CI 0.24–0.29). Based on matched pairs, the 5-year OS in patients who achieved pCR was 94% versus 77% among patients who did not (p<0.001). Conclusions: The use of NACT among patients with TNBC has dramatically increased in the last decade. We observed an increase in pCR which is likely associated with improved cancer therapy regimens and use of NACT in patients with low burden disease. Our findings highlight the importance of NACT use and the prognostic significance of pCR in this population. Although TNBC is more prevalent in Black patients, they were less likely to be treated with NACT and less likely to achieve a pCR. Additional studies are needed to explore disparities in NACT receipt and how to address these to further improve survival outcomes.