Going against the tide: increasing incidence of colorectal cancer among Koreans, Filipinos, and South Asians in California, 1988–2007

Abstract

Colorectal cancer has declined markedly in California for all major racial/ethnic groups, including Asian/Pacific Islanders as a whole. Analyzing cancer data for Asian/Pacific Islanders collectively masks important differences that exist between individual Asian subgroups. This study examines secular, sex-, age-, and socioeconomic-specific trends in colorectal cancer incidence among six Asian subgroups-Chinese, Japanese, Filipino, Korean, Vietnamese, and South Asian-to determine whether these groups experienced a decline in colorectal cancer incidence and to assess possible differences in colorectal cancer incidence trends among these groups. Cases of invasive colorectal cancer diagnosed among Japanese, Chinese, Filipinos, Koreans, Vietnamese, and South Asians between 1988 and 2007 were identified using the California Cancer Registry database. Secular, sex-, age-, and socioeconomic-specific trends in the age-adjusted colorectal cancer incidence rates for each Asian subgroup were examined using joinpoint analysis to estimate the annual percent change (APC). Among males, Koreans (APC, 3.6%) were the only group that experienced a significant increase in colorectal cancer incidence. Among females, Koreans (APC, 2.7%), South Asians (APC, 2.8%), and Filipinos (APC, 1.6%) experienced significant increases. Stratification by age at diagnosis revealed that Korean males (APC, 3.4%) and females (APC, 2.9%) as well as Filipino females (APC, 1.8%) aged 50years and older experienced a significant increase in colorectal cancer incidence. Korean males aged less than 50years (APC, 3.4%) also experienced a significant increase. Japanese (APC, -1.2%) and Chinese (APC, -1.6%) males aged 50years and older experienced a significant decrease in colorectal cancer incidence. Stratification by socioeconomic status (SES) revealed that Korean males (APC, 2.5%) and females (APC, 2.9%) as well as Filipino females (APC, 2.1%) in the lowest SES category experienced a significant increase in colorectal cancer incidence. Korean males (APC, 5.2%) and females (APC, 3.1%) as well as Filipino males (APC, 1.5%) in the highest SES category also experienced a significant increase. Japanese males (APC, -2.5%) and females (APC, -2.0%) as well as Chinese males (APC, -2.8%) and females (APC, -2.9%) in the lowest SES category experienced a significant decrease. Chinese males in the middle (APC, -3.4%) and highest (APC, -3.5%) SES categories also experienced significant decreases in colorectal cancer incidence. In contrast to the decreasing trends in colorectal cancer incidence reported among all major racial/ethnic groups including Asian/Pacific Islanders, colorectal cancer is actually increasing among some Asian subgroups in California including Korean males and females, as well as South Asian and Filipino females. Furthermore, the colorectal cancer incidence trends for these Asian subgroups differ with respect to age at diagnosis and socioeconomic status. These findings suggest that more efforts need to be made to target these populations with culturally sensitive cancer prevention and screening programs. More research is needed to examine the differences in the colorectal cancer burden among these populations.