Impact of immigration and acculturation on mortality in Asian American women with breast cancer

Purpose: Immigration/acculturation may affect breast cancer outcomes among minoritized racial and ethnic populations. Limited data exist on how these factors influence survival in Asian American women with breast cancer. We investigated associations of immigration/acculturation with all-cause (ACM) and breast cancer-specific mortality (BCSM) in this population. Methods: 3971 Asian American women with breast cancer were included from the Asian American Resiliency and Cancer Disparities (ARC) Study. Measures of immigration/acculturation included nativity (born in the US vs. outside the US), number of years (y) and percent (%) of life lived in the US, age at immigration, Asian country of birth, and preferred language at interview. Primary outcomes were ACM and BCSM. Cox proportional hazards were used to estimate hazard ratios (HRs) for ACM and Fine and Gray competing risk models for BSCM, adjusted for clinical, demographic, socioeconomic, reproductive, and lifestyle factors. Analyses were stratified by follow-up duration (≤10 y and >10 y). Results: Women born outside the US had lower ACM compared with women born in the US at 10 y (HR 0.72, 95% CI 0.61-0.85, p<0.001) and beyond 10 y (HR 0.72, 95% CI 0.63-0.82, p<0.001) follow-up. No statistically significant differences by nativity in BCSM were observed overall; however, higher BCSM in women born outside the US after 15 y of follow-up was suggested. Among women born outside the US, living longer in the US was associated with higher ACM, particularly beyond 40 and 50 y (HR 1.49, 95% CI 1.05-2.10, p=0.02; HR 1.94, 95% CI 1.34-2.81, p<0.001, respectively), which became non-significant after adjustment. Earlier age at immigration was associated with lower ACM and BCSM, and immigration in late adulthood (≥55 y) with higher ACM (<10-y HR 2.04, 95% CI 1.09-3.80, p=0.02; >10-y HR 2.05, 95% CI 1.23-3.41, p=0.006). However, after adjustment, associations with ACM remained significant only for immigration in adolescence (13-17 y) (<10-y HR 0.56, 95% CI: 0.36-0.88, p=0.01) and early adulthood (25-34 y) (>10-y HR 0.75, 95% CI: 0.59-0.96, p=0.02). For BCSM, associations were seen for immigration in adolescence (<10-y HR 0.56, 95% CI: 0.34-0.92, p=0.02), adult transition (18-24 y) (>10-y HR 0.71, 95% CI: 0.52-0.97, p=0.03) and middle adulthood (35-54 y) (<10-y HR 0.62, 95% CI: 0.39-0.97, p=0.04; >10-y HR 0.60, 95% CI: 0.40-0.88, p=0.01). No significant associations were observed between % of life in the US, Asian country of birth, or preferred language at interview, and ACM or BCSM. Conclusions: Immigration factors may influence long-term mortality in Asian American women with breast cancer. Women born outside the US demonstrated lower ACM, but the length of stay in the US and age at immigration may have influenced this association. This highlights the need for culturally tailored survivorship and public health interventions that promote native cultural behaviors in this population.