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

Background and Aims: 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. Methods: 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 kappa statistic. Results: Over 39 months to March 2021, 400 consecutive LNPCPs (median lesion size, 35 mm; 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 thorn VCE was very high (kappa = .96) with no benefit gained by the addition of DBC. Conclusions: 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.

Automated summary

The use of high-definition white-light imaging and virtual chromoendoscopy may be sufficient for predicting submucosal invasive cancer in large nonpedunculated colorectal polyps. Additionally, the absence of a demarcated area strongly predicts the absence of submucosal invasive cancer, regardless of the use of dye-based chromoendoscopy.