BACKGROUND: It is unclear whether the higher rate of colorectal cancer (CRC) among non-Hispanic blacks (blacks) is due to lower rates of CRC screening or greater biologic risk. OBJECTIVE: We aimed to evaluate whether blacks are more likely than non-Hispanic whites (whites) to develop distal colon neoplasia (adenoma and/or cancer) after negative flexible sigmoidoscopy (FSG). DESIGN: We analyzed data of participants with negative FSGs at baseline in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial who underwent repeat FSGs 3 or 5 years later. Subjects with polyps or masses were referred to their physicians for diagnostic colonoscopy. We collected and reviewed the records of diagnostic evaluations. PARTICIPANTS: Our analytic cohort consisted of 21,550 whites and 975 blacks. MAIN MEASURES: We did a comparison by race (whites vs. blacks) in the findings of polyps or masses at repeat FSG, the follow-up of abnormal test results and the detection of colorectal neoplasia at diagnostic colonoscopy. KEY RESULTS: At the follow-up FSG examination, 304 blacks (31.2 %) and 4183 whites (19.4 %) had abnormal FSG, [adjusted relative risk (RR) = 1.00; 95 % confidence interval (CI), 0.90–1.10]. However, blacks were less likely to undergo diagnostic colonoscopy (76.6 % vs. 83.1 %; RR = 0.90; 95 % CI, 0.84–0.96). Among all included patients, blacks had similar risk of any distal adenoma (RR = 0.86; 95 % CI, 0.65–1.14) and distal advanced adenoma (RR = 1.01; 95 % CI, 0.60–1.68). Similar results were obtained when we restricted our analysis to compliant subjects who underwent diagnostic colonoscopy (RR = 1.01; 95 % CI, 0.80–1.29) for any distal adenoma and (RR = 1.18; 95 % CI, 0.73–1.92) for distal advanced adenoma. CONCLUSIONS: We did not find any differences between blacks and whites in the risk of distal colorectal adenoma 3–5 years after negative FSG. However, follow-up evaluations were lower among blacks.
Bibliographical noteFunding Information:
Dr Laiyemo is supported by a grant award from the National Center for Advancing Translational Science (KL2TR000102 and UL1RT000101) and R21DK100875. The content is solely the responsibility of the authors, and does not necessarily represent the official views of the National Center for Advancing Translational Science and the National Institutes of Health.
Dr. Doubeni is supported by grants numbers 5K01CA127118 and U01CA151736 from the National Cancer Institute of the National Institutes of Health.
© 2015, Society of General Internal Medicine.
- adenomatous polyps
- colorectal cancer disparities
- flexible sigmoidoscopy