Among patients with diminutive (1-5 mm) colonic polyps, multiplicity was a significant risk factor for advanced metachronous colonic neoplasia, while advanced histologic features alone were not, according to the results of a pooled analysis of data from 64,344 patients.
Metachronous advanced neoplasia affected similar proportions of patients with and without high-risk diminutive polyps (17.6% vs. 14.6%, respectively; relative risk, 1.13; 95% confidence interval, 0.79-1.61), reported Jasper L.A. Vleugels, MD, of the University of Amsterdam, together with his associates. However, patients with at least three nonadvanced (diminutive or small) adenomas were at significantly increased risk of metachronous advanced neoplasia, compared with low-risk patients (overall risk ratio, 2.12; 95% CI, 1.89-2.38), the investigators wrote in the February issue of Gastroenterology.
This multicenter study spanned 12 prospectively evaluated cohorts of patients in the United States and Europe. All patients underwent colonoscopy because of a positive fecal immunochemical test result or for the purpose of screening, surveillance, or evaluation of symptoms. The researchers defined low-risk patients as individuals with one or two diminutive or small nonadvanced adenomas. In contrast, “high-risk” patients had a polyp with advanced histology (at least a 25% villous component, high-grade dysplasia, or colonic rectal carcinoma), at least three diminutive (1-5 mm) or small (6-9 mm) nonadvanced adenomas, or an adenomatous or sessile serrated lesion measuring at least 10 mm.
Among more than 50,000 diminutive polyps in the dataset, the prevalence of advanced histologic features was 7.1% among patients who underwent colonoscopy because of a positive fecal immunochemical test and 1.5% among those who had a colonoscopy for other reasons (P = .04). However, statistically similar proportions of patients in each of these subgroups were classified as “high risk” because of advanced histology (0.8% and 0.4%, respectively) or multiplicity (3.8% and 3.0%, respectively). Because metachronous advanced neoplasia was detected in similar proportions of patients with and without diminutive polyps with advanced histologic features (17.6% vs. 14.6%, respectively), the presence of such features did not independently predict metachronous advanced neoplasia, either overall (relative risk, 1.13; 95% CI, 0.79-1.61), or in either subgroup.