Objectives: We investigated heterogeneity in ethnic composition and immigrant status among US Asians as an explanation for disparities in breast cancer survival.
Methods: We enhanced data from the California Cancer Registry and the Surveillance, Epidemiology, and End Results program through linkage and imputation to examine the effect of immigrant status, neighborhood socioeconomic status, and ethnic enclave on mortality among Chinese, Japanese, Filipino, Korean, South Asian, and Vietnamese women diagnosed with breast cancer from 1988 to 2005 and followed through 2007.
Results: US-born women had similar mortality rates in all Asian ethnic groups except the Vietnamese, who had lower mortality risk (hazard ratio [HR] = 0.3; 95% confidence interval [CI] = 0.1, 0.9). Except for Japanese women, all foreign-born women had higher mortality than did US-born Japanese, the reference group. HRs ranged from 1.4 (95% CI = 1.2, 1.7) among Koreans to 1.8 (95% CI = 1.5, 2.2) among South Asians and Vietnamese. Little of this variation was explained by differences in disease characteristics.
Conclusions: Survival after breast cancer is poorer among foreign- than US-born Asians. Research on underlying factors is needed, along with increased awareness and targeted cancer control.