Effects of social inequality on stage of diagnosis of colorectal cancer in Illinois

Early detection is crucial in survival improvement for colorectal cancer (CRC). Thus, stage at diagnosis of CRC is recognized as an important measure of the effectiveness of cancer control. Based on social epidemiological theory, socio-contextual factors play a critical role in understanding individuals' health status and health behavior. To understand contextual effects on CRC diagnosis stage, the Illinois stage cancer registry between 1989 and 1998 and the 1990 US Census of Population and Housing were used to develop a random effect logistic regression model.; The major contextual variables included urban/rural contrast, income inequality, and two major socioeconomic attributes representing availability of resources and relative social position. Individual characteristics, including age, race, gender, and smoking status, were simultaneously taken into account. The temporal trend was also assessed.; Results indicated that the socioeconomic condition of the residential neighborhood had a significant impact on stage at diagnosis of CRC. Communities with fewer resources and at lower levels of the social hierarchy present a greater risk of late diagnosis. A reverse effect of urbanization from the original prediction was observed. The data suggested that in Illinois, CRC cases reported from communities with more urban residents had a greater risk of late diagnosis, even when individual attributes and other neighborhood characteristics were statistically controlled. Results also indicated that with equal neighborhood living conditions and area random effects, being younger, African American, and a smoker increased the risk of late diagnosis. No significant interaction was found, except that relative ranking of social position appeared to have greater impact on men than women. Although an improving trend of diagnosis stage was observed between 1989 and 1998, the effect was not statistically significant.; This study illuminated the factors at both the contextual and the individual level related to stage at diagnosis of CRC in Illinois. Identifying areas with excess rate of late diagnosis and then exploring associated factors should help to improve cancer control in these neighborhoods. The findings should help policy makers to design more effective interventions to promote CRC screening and to eliminate barriers to receiving other preventive health care services.