Neighborhood socioeconomic status and behavioral pathways to risks of colon and rectal cancer in women

BACKGROUND: Neighborhood amenities and resources plausibly determine individual modifiable risk factors for colon and rectal cancer. Evidence on the associations between neighborhood socioeconomic status (SES) and incident colon and rectal cancer is limited. METHODS: The authors analyzed a prospective cohort of 111,129 women in the Nurses' Health Study with no history of cancer in 1986 followed to 2006. Neighborhood SES was based on Census-derived characteristics of block groups of residence. Cox models were used to estimate the multivariate-adjusted associations between neighborhood SES and incident colon and rectal cancer, and to examine for effect modification. For significant associations, path models were estimated with behavioral risk factors included as potential mediators. RESULTS: Neighborhood SES was unassociated with colon cancer among all women. However, among women with college or greater education, higher neighborhood SES was inversely related to colon cancer (P for trend = .01; P for interaction between neighborhood SES and education = .03). Path analysis suggested mediation by red meat intakes and body mass index (BMI). Higher neighborhood SES was inversely related to rectal cancer among all women (relative risk in highest quintile, 0.64; 95% confidence interval, 0.44-0.93; P for trend = .08). Path analysis was consistent with mediation by multivitamin use and BMI. CONCLUSIONS: These findings suggest that living in a higher-SES neighborhood may protect against rectal cancer in women and colon cancer in higher-educated women, mediated by selected behavioral risk factors. Risk factor differences between colon and rectal cancer may account for discrepancies in estimated neighborhood effects by cancer site.