Abstract B51: Racial differences in socioeconomic status, health-related behaviors, and rectal cancer risk

Background: Racial differences in colorectal cancer (CRC) persist despite the overall decreases in both incidence and mortality attributable to screening and improved treatment modalities, with African Americans having the highest rates among all U.S. race/ethnic groups. Most of the reasons for this disparity remain unknown.

Objectives: 1) To assess the differences in socioeconomic factors, health conditions, and health-related behaviors between Whites and African Americans without rectal cancer, and 2) determine if risk of rectal cancer associated with these factors differs by race.

Methods: We used self-reported data from the North Carolina Colon Cancer Study-Phase 2, a population-based case-control study of 998 rectal (including sigmoid and rectosigmoid junction) cancer cases (751 White, 247 African American) and 989 controls (820 White, 169 African Americans). A chi-square test for independence was used to determine if socioeconomic factors (education, income, marital status, health insurance) health conditions (body mass index, diabetes, hypertension, history of cancer), and health-related behaviors (smoking, alcohol use, fruit/vegetable consumption, physical activity, screening) differed by race. Logistic regression with control for confounders was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI).

Results: Among controls,Whites had significantly higher education and income levels than African Americans, while a significantly larger portion of African Americans (5.4%) had no health insurance compared to Whites (2.1%). African Americans reported a greater prevalence of hypertension, diabetes, and obesity than Whites (all chi-square p-values <0.001), and Whites were more likely to have a family history of CRC (11.2%) than African Americans (5.4%). Smoking status and physical activity did not differ by race, but more Whites reported consuming at least five servings of fruits/vegetables per day than African Americans (73.8% vs. 62.7%, p=0.004). After adjusting for age and sex, diabetes was positively associated with rectal cancer risk in Whites (OR: 1.55 95% CI: 1.17–2.06); for African Americans, the association was inverse but not statistically significant (OR: 0.73 95% CI: 0.46–1.16). In Whites, high fruit/vegetable consumption correlated with reduced risk of rectal cancer (OR: 0.69 95% CI: 0.55–0.86), and surprisingly, with significantly elevated risk in African Americans (OR: 1.73 95% CI: 1.13–2.66).

Conclusion: These findings suggest that socioeconomic indicators, chronic health conditions, and health behaviors differ by race, which may in part contribute to racial differences in rectal cancer risk. This study underscores the need to examine these associations separately by race, ideally in racially diverse study populations.