Disaggregation of Asian American and Pacific Islander Data Reveals Heterogeneous Outcomes After Neoadjuvant Chemotherapy for Invasive HER2-Positive Breast Cancer.

BackgroundHER2-positive (HER2+) invasive breast cancer is more prevalent among Asian American and Pacific Islander (AAPI) women. We evaluated response to neoadjuvant chemotherapy (NAC) to identify disparities among disaggregated AAPI subgroups.MethodsWomen with HER2+ breast cancer in the 2018-2020 National Cancer Database who received NAC followed by surgical excision were identified. Patients were categorized as White, AAPI, or Non-White Non-Asian (NWNA), followed by analysis of AAPI subgroups. The primary outcome was pathologic complete response (pCR).ResultsOf 14,110 women, 10,603 (75.1%) were White, 964 (6.8%) AAPI, and 2543 (18.0%) NWNA. Asian American and Pacific Islander patients had the highest overall pCR rate at 43.3% compared with 42.5% in White and 36.1% in NWNA patients ( < .001). Disaggregation revealed heterogeneity: Pacific Islander patients had the lowest pCR rate (35.6%), below both White and NWNA cohorts, while Korean patients had the highest pCR rate (54.6%) (both < .001). Pacific Islander patients were more likely to present with comorbidities, advanced clinical stage, lymphovascular invasion, and experienced the longest time to chemotherapy. Korean patients were least likely to present with advanced disease, nodal involvement, or lymphovascular invasion and had the shortest time to chemotherapy. On multivariable analysis, nodal positivity, lymphovascular invasion, and increasing time to chemotherapy-not race/ethnicity-were independent negative predictors of pCR.DiscussionDisaggregated AAPI data are essential to identify vulnerable subgroups, prioritize timely neoadjuvant therapy, and inform targeted interventions that may reduce disparities in treatment response.