The risk of advanced histology in small-sized colonic polyps: Are non-invasive colonic imaging modalities good enough?

Purpose The study aims to evaluate the risk of advanced histology within small colonic polyps and assess whether this risk warrants different recommendation for surveillance and treatment of such polyps. Methods A retrospective study of all patients undergoing their first ever colonoscopy and polypectomy in a tertiary hospital for one of three indications: screening, positive family history, and positive occult blood in stool. The histological reports of all resected polyps were retrieved and stratified according to the various polyps' sizes. Advanced neoplasia was defined as tubular adenoma ≥10 mm or any size polyp with advanced histology, i.e., villous or tubulovillous adenoma, high-grade dysplasia, intramucosal carcinoma, or invasive cancer. Results Seven hundred forty-one patients who had a total of 1,192 resected polyps were included. Of polyps ≤5 mm in size, 1.6% harbored invasive cancer or high-grade dysplasia, and additional 4.1% contained villous component. The rate of advanced histology for polyps sized 6-9 mm was over 15%. The rate of advanced histology in polyps ≤5 mm was not significantly different when employing sensitivity analysis accounting for possible under or overestimation of polyp sizes by 1 and 2 mm. However, 4.6% of polyps sized 6-9 mm were found to harbor an invasive or high-grade dysplasia component when taken into account a 2-mm overestimation. Conclusions A non-negligible fraction of small polyps harbor advanced histology. This finding suggests that expectant follow-up by non-invasive colonic imaging modalities for small polyps or not reporting them may put more than 5% of patients at risk of dysplasia progression.