Colon Cancer Screening: Race as an Determinant of Risk

MedicalResearch.com Interview with: Paul C. Schroy III, M.D., M.P.H.
Professor of Medicine, Boston University School of Medicine
Director of Clinical Research, GI Section, Boston Medical Center
85 East Concord Street, Room 7715
Boston, MA 02118

MedicalResearch.com: What are the main findings of the study?

Dr. Schroy:  Our study affirms the importance of race as an independent determinant of risk.

However, contrary to the results of several previously published studies, we found that the prevalence of advanced colorectal neoplasia (ACN), the target of colorectal cancer screening, was higher among whites than blacks overall, and in particular, white men compared to black men in a safety-net health care system after adjustment for other known CRC risk factors.  Although no significant differences were observed between white and black women, our findings are inconclusive, presumably due to the low prevalence of ACN in this subgroup.  Like others ,, we did observe a predilection for proximal disease among blacks compared to whites with ACN.  The findings related to differences in the overall prevalence of ACN are noteworthy since similar sex-specific relationships were observed for CRC incidence rates among whites and blacks prior to the rise in screening rates.

MedicalResearch.com: Were any of the findings unexpected?

Dr. Schroy:  Our findings are provocative since prior studies found either higher rates among blacks or no differences. We speculate that differences in the primary endpoint (e.g., polyp size vs. histopathology), selection criteria, setting, racial misclassification, ethnic mix, and/or differential exposure to modifiable risk factors for ACN (e.g., smoking or prior colonoscopy) may explain this variance.

MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Schroy:

*  Our findings provide new evidence suggesting that disparities in access to screening and differential exposure to modifiable risk factors rather than genetic differences are largely responsible for the higher overall incidence of CRC among blacks, especially black men.  We believe these findings have important public health implications since they highlight the need for targeted strategies aimed at increasing screening rates among blacks in settings where disparities exist.  These strategies must not only address barriers to access (e.g., lack of health care insurance) but also patient and physician level barriers to acceptance, adherence and utilization.  Despite the predilection for proximal disease among blacks with ACN, the relatively high proportion of patients with proximal disease in both groups supports the use of colonoscopy over flexible sigmoidoscopy for whites and blacks undergoing endoscopic screening.  Our study also reinforces the importance of risk-reducing lifestyle changes (e.g., smoking cessation), which may account for another 34-46% of the variation in risk.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Schroy:

*  Future research is warranted to identify cost-effective strategies for addressing patient, provider and system-level barriers to CRC screening that promote uptake in settings where disparities exist.  Future research is also warranted to better define the extent to which genetic or biologic factors might explain the predilection for proximal disease among blacks.

Prevalence of Advanced Colorectal Neoplasia in White and Black Patients Undergoing Screening Colonoscopy in a Safety-Net Hospital

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