Abstract PD1-05: Real-world adoption, disparities and impact of neoadjuvant chemoimmunotherapy (NACT-IO) in early-stage, high-risk triple negative breast cancer (TNBC)

Abstract Background: NACT-IO has transformed the treatment landscape for early-stage, high-risk TNBC, a clinically aggressive subtype of breast cancer (BC) associated with less favorable survival outcomes. However, the real-world adoption and impact of NACT-IO on BC outcomes are not clearly understood. Using data from a large national hospital-based cancer registry, we examined trends and factors associated with NACT-IO use and pathologic complete response (pCR), and the impact on breast-conserving surgery (BCS) and overall survival (OS). Methods: Patients aged 18 years or older with clinical stage II-III TNBC diagnosed between 2017-2022 who received neoadjuvant chemotherapy (NACT) and underwent surgery were identified in the National Cancer Database. Trends in NACT-IO use and pCR over time were evaluated using the Cochran-Armitage test for time trend. Multivariable logistic regression was used to assess factors associated with receipt of NACT-IO and likelihood of pCR. The association between NACT-IO use and receipt of BCS was also examined using multivariable logistic regression. The impact of pCR on OS was evaluated using a multivariable Cox proportional hazards model with propensity score (PS) weighting and 1:1 matching by year of diagnosis and clinical stage. Results: Among 41,339 patients with early-stage TNBC who received NACT, 28.8% received NACT-IO. NACT-IO use increased significantly over time from 2.9% in 2017 to 81.9% in 2022 (p