Incidence Rates of Colorectal Cancer in South Asians, Other Asian Groups, and Non-Hispanic Whites in California

Abstract

Introduction: The incidence of colorectal cancer (CRC) varies by race and region. South Asians constitute a fast-growing group in the U.S. and are concentrated in California. We studied the most recent incidence rates and trends of CRC in South Asians in comparison to other Asian groups and Non-Hispanic Whites in California. Methods: Using the California Cancer Registry SEER*Stat database, we calculated age-adjusted CRC incidence rates between 2011-2015 for South Asians, other Asian groups, and Non-Hispanic Whites. We defined South Asians as Asian Indians, Pakistanis, Bangladeshis, Sri Lankans, Nepalis, Bhutanese, and Maldivians. We also studied the annual percentage change (APC) in CRC incidence rates in South Asians, other Asian groups, and Non-Hispanic Whites between 1988-2014. Results: South Asians had a significantly lower incidence of colon, rectal, and rectosigmoid cancer than other Asian groups and non-Hispanic Whites, among both males and females (Table 1). Males in other Asian groups had higher CRC rates than Whites. Both proximal and distal CRC incidence rates in South Asians were lower than other Asians and Whites. Distal CRC rates were higher in other Asian groups than in Whites. Whites had the highest CRC incidence in the <50-year age group. No significant change was noted in the incidence rates of CRC in South Asians between 1988-2014 (Table 2, p<0.05). There was a significant decrease in the rates of colon (proximal and distal) and rectal carcinoma in other Asians in both males and females between 2000-2014 (Table 2, p<0.05), and in Whites (proximal and distal) in both males and females between 1988-2014 (Table 2, p<0.05). CRC rates in the <50-year age group increased significantly in Whites between 1992-2014, and non-significantly in South Asians and other Asians (Table 2, p<0.05). Conclusion: In this study, we found that South Asians had a significantly lower incidence of CRC in comparison to other Asian groups and Non-Hispanic Whites. CRC rates in other Asians is approaching that of Whites. CRC incidence trends show a significant decrease in other Asian groups and in Non-Hispanic Whites between 1988-2014, but not in South Asians. CRC rates are increasing in the <50-year age group across all racial groups. Continued efforts are needed to reduce the incidence of CRC in Asian populations, and to further investigate the etiologies of younger onset CRC.256_A Figure 1. Age adjusted incidence rates of CRC in South Asians, other Asian groups, and Non-Hispanic Whites in California between 2011-2015.256_B Figure 2. Trend in CRC incidence rates in South Asians, other Asian groups, and Non-Hispanic Whites in California between 1988-2014.