Background ?Recent data indicate that the risk of cancer in colorectal lesions <10mm is lower than previously reported, possibly reflecting improved detection of flat, low-volume lesions with a low risk of cancer. Few studies have examined the prevalence of cancer in colorectal lesions 10-19mm in size. Methods ?We reviewed a prospectively collected database of all colorectal lesions removed at a single endoscopy center in order to identify lesions of 10-19mm in size and review their histology. Lesions ≥20mm were evaluated as a control group.We reviewed photographs of cancerous lesions to determine the frequency of endoscopic features of cancer. Results ?A total of 5093 lesions ≥10mm were removed from 4020 patients (mean age 63.2 years, 34.4% female). Among 3068 lesions 10-19mm in size, 28 (0.9%) had adenocarcinoma, including 1.2% of conventional adenomas and 0.3% of serrated class lesions. These rates were lower than the 6.9% and 2.0% rates of cancer found in conventional adenomatous lesions and serrated lesions ≥20mm, respectively. Cancer was suggested by endoscopic features in 52.0% of malignancies 10-19mm in size compared with 79.2% of lesions ≥20mm. Conclusions ?The prevalence of cancer in 10-19mm colorectal lesions was much lower than previously reported. The cancer risk was higher in conventional adenomas than in serrated lesions. Cancer was endoscopically evident prior to resection in slightly more than half of colorectal lesions 10-19mm in size.
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