Survival in colorectal cancer with Asian ethnicity

Abstract

4042 Background: It has been reported that Asian ethnicity confers a survival benefit in colorectal cancer (CRC) when compared to the other major ethnic groups. The reasons for this have not yet been clearly elucidated. We set out to determine differences in CRC clinical characteristics at presentation and survival, among Asian subsets using data from the large, population-based California Cancer Registry (CCR). Methods: The authors conducted a case-only analysis of CCR data (1994–2004), including descriptive analysis of relevant clinical variables and Asian subsets. Overall survival (OS) univariate analyses were conducted using the Kaplan-Meier method. Multivariate survival analyses were performed using Cox proportional hazards ratios. Results: 61,494 incident cases of colon and 24,350 incident cases of rectal cancer were analyzed, including 1,905 Chinese, 1,162 Filipino, 414 Vietnamese, 391 Korean, 1,091 Japanese, 148 Asian Indian, and 77,554 Caucasians. Sigmoid colon tumors were most common among Filipinos (32%) and least common among Caucasians (22%). After adjustment for age, sex, grade, histology, site within the colon, stage, insurance status, socioeconomic status (SES), and therapy, Filipino (Colon: HR, 0.85; 95% CI, 0.76–0.95; Table 1) (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, 0.93; 95% CI, 0.89–0.96) (Reference=prox and transverse lesions), and among Asian-only cases in separate analysis (HR, 0.78; 95% CI, 0.70–0.87). Conclusion: Although survival after CRC diagnosis is improved for Asians in general, significant survival differences are observed only in specific Asian subsets. These differences are not well understood but our data suggest survival among Asians is less affected by SES or treatment disparities, and may be due to biologic factors. Multivariate colorectal cancer-specific survival analysis for colon and rectum by ethnicity Race Colon HR (95% CI) Rectum HR (95% CI) White 1.00 (Reference) 1.00 (Reference) Chinese 0.90 (0.92–0.98) 1.00 (0.87–1.16) Filipino 0.85 (0.76–0.95) 0.82 (0.71–0.94) Vietnamese 0.90 (0.75-1.09) 0.96 (0.73–1.25) Korean Japanese 1.10 (0.91–1.32) 0.92 (0.82–1.03) 0.84 (0.67–1.06) 0.84 (0.70–1.00) Other Southeast Asian 1.22 (0.88–1.67) 1.02 (0.67-1.55) Other Asian Asian Indian 0.87 (0.72–1.06) 0.87 (0.61-1.24) 1.07 (0.82–1.40) 0.98 (0.61–1.55) Adjustment made for age, gender, histologic grade, AJCC stage, insurance status, socioeconomic status, colon site, surgery, radiation, and chemotherapy No significant financial relationships to disclose.