Differences in breast cancer survival across Asian American ethnicities compared with non-Latina White females in Kaiser Permanente Northern California.

Abstract

In the US, Asian American females with breast cancer have better survival than other groups, and survival differs across Asian American ethnicities. Reasons remain unclear. We compared the survival of 5294 Asian American ethnicities and 5294 non-Latina White (NLW) females with incident stage I-IV breast cancer (2000-2015) in Kaiser Permanente Northern California. With follow-up through December 31, 2020, survival analysis was conducted using cause-specific Cox proportional hazards models adjusting for sociodemographic, clinical, treatment, social environment, and lifestyle factors. Overall, 1048 deaths (581 breast cancer-related) occurred in Asian American females and 1673 deaths (779 breast cancer-related) in NLW females. Compared with NLW females, Asian American females were younger (median = 56.2 vs. 63.0 years), lived in the highest socioeconomic status neighborhoods (Quintiles 4/5 = 57.7% vs. 50.3%), had fewer comorbidities (45.2% vs. 35.9% with zero), had a lower body mass index (BMI) (median = 24.8 vs. 27.4 kg/m2), and never smoked (47.2% vs. 26.9%), varying by Asian American ethnicity. All-cause mortality was lower in Asian American than NLW females (hazard ratio [HR] = 0.82; 95% CI = 0.74 to 0.91). Chinese (HR = 0.84; 95% CI = 0.70 to 1.00), Japanese (HR = 0.69; 95% CI = 0.55 to 0.88), and South Asian (HR = 0.73; 95% CI = 0.53 to 0.99) females had persistent survival advantages over NLW females. Adjusting for BMI and smoking attenuated associations. For breast cancer-specific mortality, associations were similar, though statistically non-significant. Asian American females-especially those of Chinese, Japanese, and South Asian descent-had better survival than non-Latina NLW females. Disaggregating Asian American ethnicities clarifies survival differences and may inform research on personal, social, and lifestyle factors to benefit all patients.