Background: Black persons are more likely than white persons to be diagnosed with colorectal cancer and to die from it. The extent to which genetic or biological factors versus disparities in screening rates explain this variance remains controversial.
Objective: To define the prevalence and location of presymptomatic advanced colorectal neoplasia (ACN) among white and black persons undergoing screening colonoscopy, controlling for other epidemiologic risk factors.
Design: Cross-sectional survey between 22 March 2005 and 31 January 2012.
Setting: Urban, open-access, academic, safety-net hospital in Massachusetts.
Participants: Asymptomatic, average-risk white (n = 1172) and black (n = 1681) persons aged 50 to 79 years undergoing screening colonoscopy.
Measurements: Adjusted prevalence and location of ACN, defined as a tubular adenoma 10 mm or more in size, any adenoma with villous features or high-grade dysplasia, any dysplastic serrated lesion, or invasive cancer.
Results: The prevalence of ACN was higher among white patients than black patients (6.8% vs. 5.0%; P = 0.039) but varied by sex (white vs. black men, 9.3% vs. 5.7%; white vs. black women, 3.5% vs. 4.3%; interaction P = 0.034). After controlling for many risk factors, black men were 41% less likely than white men (adjusted odds ratio [AOR], 0.59 [95% CI, 0.39 to 0.89]) to have ACN. No statistically significant difference was seen for women (AOR, 1.32 [CI, 0.73 to 2.40]). Black patients with ACN had a higher percentage of proximal disease (52% vs. 39%) after adjustment for age and sex (P = 0.055).
Limitation: Single-institution study with inadequate statistical power for subgroup analyses and recall bias.
Conclusion: Black men are less likely than white men to have ACN at screening colonoscopy in a safety-net health care setting. Disparities in access to screening and differential exposure to modifiable risk factors rather than genetic or biological factors may be largely responsible for the higher incidence of CRC among black men. Genetic or biological factors may explain the predilection for proximal disease.