Survival of distinct Asian groups among colorectal cancer cases in California

Abstract

It has been reported that Asian ethnicity confers a survival benefit in colorectal cancer (CRC) compared with other ethnicities, but it is not known if this is limited to specific Asian subsets. In the current study, the authors attempted to determine differences using data from the large, population-based California Cancer Registry (CCR). The authors conducted a case-only analysis of CCR data (1994-2003), including descriptive analysis of relevant clinical variables. Overall survival univariate analyses were conducted using the Kaplan-Meier method. Multivariate survival analyses were performed using Cox proportional hazards ratios (HR). The 61,494 incident cases of colon and 24,350 incident cases of rectal cancer analyzed included 1905 Chinese, 1162 Filipino, 414 Vietnamese, 391 Korean, 1091 Japanese, 148 Asian Indian, and 77,554 Caucasians. After adjustment for age, sex, grade, histology, site within the colon, stage of disease, insurance status, socioeconomic status (SES), and therapy, Filipino (colon: HR, 0.85; 95% confidence interval [95% CI], 0.76-0.95) (rectum: HR, 0.82; 95% CI, 0.71-0.94) and Chinese ethnicity (colon: HR, 0.90; 95% CI, 0.92-0.98) had significantly decreased risk of death compared with Caucasians. Sigmoid lesions were independently associated with improved survival among all cases (HR, 0.92; 95% CI, 0.88-0.95) (referent group were proximal and transverse lesions), and among Asian-only cases in separate analysis (HR, 0.78; 95% CI, 0.70-0.87). Although survival after CRC diagnosis is improved for Asians in general, significant survival differences are observed only in specific Asian subsets. Data from the current study suggest that survival among Asians is less affected by SES or treatment disparities, and may be because of biologic factors.