Ethnic Differences in Prevalence and Location of Colorectal Adenoma: Possible Link between Hispanic Advantage and Vitamin D Status

Abstract

Purpose: Ethnic differences in the incidence of colorectal cancer (CRC) and colorectal adenoma (CRA) are well documented. The majority of these studies have been focused on black-white disparities for CRC, however research on CRA prevalence among Hispanics is lacking. The objective of this study is to evaluate ethnic disparities in prevalence of CRA and its possible mechanism, particularly for Hispanics. Methods: In this retrospective case-control study in a suburban community of New York State, 1,656 patients who underwent complete colonoscopies from 2007 to 2011 were enrolled. 1,340 pathologically confirmed adenoma cases and 316 adenoma-free controls were analyzed for the association of CRA overall or by location with ethnicity, using multivariate logistic regression analyses after adjusting for other risk factors. A secondary analysis assessed a possible link between vitamin D status and observed ethnic differences using a subset of subjects with serum 25-hydroxyvitamin D level available.Table: [1957] Association between ethnicity and colorectal adenoma by locationResults: The study participants consisted of 45% Hispanics, 17% non-Hispanic whites, 32% non-Hispanic blacks and 6% others. Of 1656 patients, 316 (19%) were diagnosed with adenomas, 142 (8.6%) proximal adenomas, 93 (5.6%) distal adenomas, 37 (2.2%) rectal adenomas and 44 (2.7%) were found to have adenomas at multiple sites. The prevalence of CRA for Hispanics was lower than non-Hispanic whites and blacks (14.8% vs 22.5%; adjusted OR, 0.67; 95% CI, 0.47-0.96; P<0.01), while no differences were noted between whites and blacks. The reduced CRA prevalence among Hispanics vs. non-Hispanics was more pronounced for proximal adenoma (5.3% vs 11.2%; adjusted OR, 0.42; 95% CI, 0.26-0.70; P<0.001), but not significant for adenoma at other locations. In a subset of patients (n=128), we found higher serum 25-hydroxyvitamin D levels among Hispanics than non-Hispanics, as well as in controls than adenoma cases. Conclusion: Our data suggest a distinction between Hispanics and non-Hispanics in the risk of CRA. The lower adenoma rates, particularly proximal adenoma rates, for Hispanics might be partially attributed to better vitamin D status. These findings might be community-specific, thus additional multi-center studies are needed.