, prompting investigators to suggest that the age at which screening starts need not differ based on race.
There was also no difference in advanced neoplasia in the proximal colon between black and white screen-eligible individuals in the most rigorous of the studies included in the meta-analysis, investigators reported.
Those findings support eliminating the age difference at which to begin screening of average-risk individuals, as is currently recommended in some guidelines, said Thomas F. Imperiale, MD, the Lawrence Lumeng Professor of Gastroenterology and Hepatology at Indiana University, Indianapolis, and his coinvestigators.
In areas with no disparities in screening access, average-risk screening could begin at age 50 years, regardless of race, at least based on results of this meta-analysis, Dr. Imperiale and his colleagues said in their report.
“To the extent that advanced adenoma is the precursor lesion for colorectal cancer, tailoring the age at which to begin screening and how to screen based on race is not supported by our findings,” they said in the report, which appears in the journal Gastroenterology.
Dr. Imperiale and his coinvestigators scanned the medical literature and identified nine studies looking at the prevalence of advanced adenomas or advanced precancerous colorectal neoplasms in both black and white individuals of average risk who had undergone screening colonoscopy.
Those nine cross-sectional studies, all published during 2010-2017, represented a total of 302,128 participants. Six studies were of high methodologic quality and had a low risk of bias, while the remaining three failed to adjust for age and sex, authors of the meta-analysis said in their report.
Prevalence of advanced adenomas or advanced precancerous colorectal neoplasms ranged from 2% to 10% for whites and from 5% to 12% for blacks in the nine studies, with only one study, which had no histology results available, showing a higher prevalence in blacks, investigators found.
Taken together, there was no difference between racial groups, with a point prevalence of 6.57% for blacks and 6.20% for whites (odds ratio, 1.03; 95% confidence interval, 0.81-1.30) and an absolute risk difference of zero, according to the statistical analysis.
Of five studies that included data on proximal advanced adenomas or advanced precancerous colorectal neoplasms, two showed a greater prevalence in blacks versus whites, with point prevalences of 3.30% and 2.42%, respectively. However, there was no difference in prevalence for the “best subset” of three studies with a moderate degree of heterogeneity, investigators said.
Given these findings, the higher colorectal cancer incidence and mortality seen in black adults is less likely because of biology, and more likely from differences in symptom recognition, diagnostic evaluation, or acceptance of preventive services, Dr. Imperiale and his coauthors said in a discussion of the results.
Some current guidelines suggest starting colorectal cancer screening at age 40 years for average-risk blacks, which is 5-10 years earlier than for nonblacks, investigators said, though of note, the most recent American Cancer Society recommendations recommend screening starting at age 45 years for all average-risk individuals.
“If this recommendation is followed broadly, it would lessen the clinical and policy implications of our findings,” they wrote. “However, the uptake of this recommendation is yet to be determined, as it differs from those of all other professional organizations.”
The study was supported by Indiana CTSI Collaboration in Translational Research Grants. Dr. Imperiale and hiscoauthors reported no conflicts of interest.
SOURCE: Imperiale TF et al. Gastroenterology. 2018 Aug 21. doi: 10.1053/j.gastro.2018.08.020.