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Right-sided colon polyps with advanced pathology smaller than lesions in left colon
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Colon polyps with high-grade dysplasia, adenocarcinoma or advanced neoplasia are of smaller size in the right colon than the left, suggesting a need for improved colorectal cancer detection, according to recent study results.
In a cross-sectional study, researchers evaluated 233,414 colon polyps occurring in 142,686 patients (53.4% male) aged 40 to 85 years. The size of polyps with high-grade dysplasia (HGD), adenocarcinoma or advanced neoplasia was compared between those located in the left (51% of evaluated polyps) and right colon. Polyp size was identified according to the largest analyzed fragment in each case.
Polyps with high-grade dysplasia (HGD) or adenocarcinoma were smaller in the right colon than the left colon (mean size 8.2 mm vs. 12.4 mm), as were polyps with advanced neoplasia (7.6 mm compared with 11.1 mm) (P<001). The majority of polyps in the right colon with HGD, adenocarcinoma or advanced neoplasia were 9 mm or smaller (69.7%, HGD or adenocarcinoma; 76.7%, neoplasia), while most polyps located in the left colon were larger than 9 mm (62.7%, HGD/adenocarcinoma; 53.3%, neoplasia).
Both polyps with HGD or adenocarcinoma (OR=5.27, 4.06-6.82) and those with advanced neoplasia (OR=4.89, 4.34-5.51) were significantly more likely to be less than 6 mm in the right colon than in the left colon. Polyps with adenocarcinoma specifically were even more likely to be smaller than 6 mm in the right colon (OR=5.80, 3.27-10.24). All associations were slightly reduced after adjusting for age and sex, but remained significant (OR=4.10, 3.15-5.34, polyps with HGD or adenocarcinoma; OR=4.39, 3.85-5.01, advanced neoplasia; OR=4.28, 2.42-7.61, adenocarcinoma specifically) (95% CI for all).
“We found that the average size of polyps with advanced pathology was smaller in the right colon as compared with the left colon,” the researchers wrote. “This observation supports the hypothesis that colonoscopy inconsistently protects against right-sided [colorectal cancer] because right-sided lesions with advanced histology are more likely to be small and therefore more likely to be missed at time of colonoscopy and progress to cancer. These data may have important implications for developing strategies to reduce right-sided [colorectal cancer] incidence and mortality.”
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