Colorectal cancer risk after removal of polyps in fecal immunochemical test based screening

Background: Colonoscopy surveillance intervals are based on the predicted risk of metachronous colorectal cancer (CRC) after polyp removal. However, risk estimation per polyp subtype is difficult due to the fact that many patients have multiple polyps. To enable risk estimation per polyp subtypes we examined the metachronous CRC risk of subgroups based on presence or absence of co-occurring findings. Methods: Using high-quality screening colonoscopies performed after a positive fecal immunochemical test between 2014 and 2020 within the Dutch CRC screening program, we applied Cox regression analysis to evaluate the association between findings at baseline colonoscopy and metachronous CRCs. For our primary outcome, we appointed each patient to unique subgroups based on removed polyp subtypes that were present or absent at baseline colonoscopy and used the groups without polyps as reference. High-risk subgroups were individuals with high-risk serrated polyps, defined as serrated polyp ≥10 mm, sessile serrated lesions with dysplasia, or traditional serrated adenomas, as well as high-risk adenomas, defined as adenoma ≥10 mm or containing high-grade dysplasia. Findings: In total 253,833 colonoscopies were included. Over a median follow-up of 36 months (IQR, 21–57), we identified 504 metachronous CRCs. Hazard ratios for metachronous CRC was 1.70 (95% CI, 1.07–2.69) for individuals with high-risk serrated polyps without high-risk adenomas, 1.22 (0.96–1.55) for individuals with high-risk adenomas without high-risk serrated polyps, and 2.00 (1.19–3.39) for individuals with high-risk serrated polyps and high-risk adenomas, compared to patients without polyps. Interpretation: Accounting for co-occurring findings, we observed an increased metachronous CRC risk for individuals that had high-risk serrated polyps with the presence of high-risk adenomas, or individuals with high-risk serrated polyps without high-risk adenomas. These findings could provide more evidence to support post-polypectomy surveillance guidelines. Funding: None.</p

Computer-aided classification of colorectal polyps using blue-light and linked-color imaging

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths. Since most CRCs develop from colorectal polyps (CRPs), accurate endoscopic differentiation facilitates decision making on resection of CRPs, thereby increasing cost-efficiency and reducing patient risk. Current classification systems based on whitelight imaging (WLI) or narrow-band imaging (NBI) have limited predictive power, or they do not consider sessile serrated adenomas/polyps (SSA/Ps), although these cause up to 30% of all CRCs. To better differentiate adenomas, hyperplastic polyps, and SSA/Ps, this paper explores the feasibility of two approaches: (1) an accurate computer-aided diagnosis (CADx) system for automated diagnosis of CRPs, and (2) novel endoscopic imaging techniques like blue-light imaging (BLI) and linked-color imaging (LCI). Two methods are explored to predict histology: (1) direct classification using a support vector machine (SVM) classifier, and (2) classification via a clinical classification model (WASP classification) combined with an SVM. The use of probabilistic features of SVM facilitates objective quantification of the detailed classification process. Automated differentiation of colonic polyp subtypes reaches accuracies of 78−96%, thereby improving medical expert results by 4−20%. Diagnostic accuracy for directly predicting adenomatous from hyperplastic histology reaches 93% and 87−90% using NBI and the novel BLI and LCI techniques, respectively, thus improving medical expert results by 26% and 20−23%, respectively. Predicting adenomatous histology in diminutive polyps with high confidence yields NPVs of 100%, clearly satisfying the PIVI guideline recommendation on endoscopic innovations (≥90% NPV). Our CADx system outperforms clinicians, while the novel BLI technique adds performance value

Advanced serrated polyps as target of screening: detection rate and positive predictive value within a fecal immunochemical test based colorectal cancer screening population

Aims Advanced serrated polyps (ASPs) have a comparable risk as advanced adenomas (AAs) to progress into colorectal cancer (CRC). The yield of most CRC screening programs, however, is based on AAs and CRC only. We assessed the ASP detection rate, and increase in positive predictive value (PPV) including ASPs in the yield of a FIT-based screening program. Methods We analysed findings of follow-up colonoscopies of FIT-positive screenees in the Dutch CRC screening program from 2014 until 2020. Data was retrieved from the national screening and pathology database. ASP was defined as any serrated polyp ≥10mm, sessile serrated lesion with dysplasia or traditional serrated adenoma. ASP detection rate was defined as the proportion of colonoscopies with ≥1 ASP. PPV was defined as proportion of persons with a CRC or AA. The updated PPV definition included CRC, AA and/or ASPs. Results In total, 322,882 colonoscopies were included in the analyses. Overall detection rate of ASPs was 5.9%. ASPs were more often detected in females than males (6.3% vs 5.6%, pConclusion A proportion of 5.9% FIT-positive screenees had ASPs, but half of these were detected in combination with CRC or AA. Therefore, including ASPs results in a small increase in the yield of FIT-based screening