Location-dependent ethnic differences in the risk of colorectal adenoma: a retrospective multiethnic study.

Background And Aims: Epidemiological data have demonstrated that Hispanics have a lower incidence rate of colorectal cancer (CRC) compared with other major race/ethnicity groups in the United States. However, data regarding the relative prevalence of colorectal adenomas (CRAs) in Hispanic versus non-Hispanic populations are currently sparse and inconclusive.

Methods: We conducted a retrospective review of colonoscopy patients (n=1656) at a single tertiary-care community hospital from 2007 to 2011, to evaluate the association of self-reported race/ethnicity status with CRA prevalence and characteristics. Established CRC risk factors were also included in multivariate regression models.

Results: Overall, the CRA prevalence was lower in Hispanic subjects than non-Hispanic subjects (14.8% vs. 22.5%) and this difference was statistically significant (adjusted odds ratio, 0.67; 95% confidence interval, 0.47-0.96; P<0.01). Conversely, no difference in CRA prevalence was observed between non-Hispanic white and black subjects. Further analyses by adenoma location revealed more pronounced reduction in proximal CRA prevalence for Hispanics versus non-Hispanics (5.3% vs. 13.1%; adjusted odds ratio, 0.42; 95% confidence interval, 0.26-0.70; P<0.001), whereas CRA prevalence in distal colon, rectum or multiple locations did not differ significantly between race/ethnicity groups.

Conclusions: Our data showed a marked distinction in CRA prevalence, particularly proximal adenomas, between Hispanics and non-Hispanics. Additional multicenter studies are needed to confirm these findings, elucidate the underlying mechanisms, and clarify the implications for CRC screening and other preventive and/or therapeutic interventions.