A Population Based Analysis of Breast Cancer Outcomes Among Disaggregated Asian American and Pacific Islander Women

Breast cancer incidence is rising among Asian women, yet aggregation of Asian American and Pacific Islander (AAPI) populations obscures meaningful subgroup differences. This study evaluated tumor biology, treatment patterns, and overall survival (OS) among disaggregated AAPI subgroups.

Using the National Cancer Database, we identified AAPI women with stage I-III invasive breast cancer diagnosed from 2004 to 2021, disaggregated into East Asians (EA), Southeast Asian (SE), South Asian (SA), and Pacific Island (PI) women. Descriptive statistics, log-rank tests, multivariable Cox regression, and Kaplan-Meier estimates were used.

A total of 72,253 AAPI women met the inclusion criteria: EAs 40%, SEAs 30%, SAs 21%, and PIs 8%. PIs had the highest comorbidity burden, lowest private insurance rates, and greatest travel burden (31% lived >20 miles from their treatment center). Tumor biology differed by subgroup: PIs had the highest Luminal A prevalence (61% vs. 54-58%), SEAs had higher human epidermal growth factor receptor 2-positive rates (5.0% vs. 3.2-3.8%), and SAs had the highest triple-negative rate (9.4% vs. 5.8-7.3%). EAs had the highest proportion of stage I disease (62% vs. 56-57%). PIs were least likely to receive hormone therapy among hormone receptor-positive patients (82% vs. 85-86%) and adjuvant radiation after lumpectomy (82% vs. 84-85%). Ten-year OS was 84% (EAs), 86% (SAs), 84% (SEAs), and 75% (PIs) (p<0.01); Cox regression confirmed the highest mortality risk among PIs (hazard ratio 1.4; 95% confidence interval 1.3-1.5, p<0.01).

Despite more favorable tumor biology, PI women experienced the poorest OS, underscoring the need for subgroup-specific strategies to improve access, treatment, and outcomes.