Incremental benefit of dye-based chromoendoscopy to predict the risk of submucosal invasive cancer in large nonpedunculated colorectal polyps

Abstract

Detailed lesion assessment of large nonpedunculated colorectal polyps (LNPCPs;≥20mm) can help predict the risk of submucosal invasive cancer (SMIC). Traditionally this has required the use of dye-based chromoendoscopy (DBC). We sought to assess the accuracy and incremental benefit of DBC in addition to high-definition white-light imaging (HDWLI) and virtual chromoendoscopy (VCE) for the prediction of SMIC within LNPCPs. A prospective observational study of consecutive LNPCPs at a single tertiary referral center was performed. Before resection all lesions were assessed for the presence of a demarcated area (DA), defined as an area of disordered pit or microvascular pattern, by 2 trained endoscopists before and after DBC. Diagnostic performance characteristics were calculated with histology as the reference criterion standard, and overall agreement was calculated using the κ statistic. Over 39 months to March 2021, 400 consecutive LNPCPs (median lesion size, 35mm; interquartile range, 25-45) were analyzed. The overall rate of SMIC was 6.5%. Presence of a DA had an accuracy of 91% (95% confidence interval, 87.7-93.5) for SMIC, independent of the use of DBC. The rate of interobserver agreement for presence of a DA using HDWLI+ VCE was very high (κ= .96) with no benefit gained by the addition of DBC. The use of HDWLI and VCE is likely to be adequate for lesion assessment for the prediction of SMIC among LNPCPs. Further, the absence of a DA is strongly predictive for the absence of SMIC, independent to the use of DBC. (Clinical trial registration number: NCT03506321.).