Kisiel, John B.

Patients with inflammatory bowel disease (IBD) are at increased risk for colorectal cancer (CRC). Despite weak supporting evidence, important logistic barriers and high cost, colonoscopy is currently the only recommended approach to CRC surveillance in patients with IBD. As such, there is imperative to explore alternative or complementary strategies with potential to improve the efficiency and effectiveness of surveillance in IBD. Given our increasing understanding of tumorigenesis in IBD and the accompanying cascade of molecular alterations, there is a strong rationale to pursue biomarker assays for this application. Stool-based DNA testing with advanced technology has been shown to be highly discriminatory for detection of sporadic colorectal cancer and advanced precancers. In early observations, stool DNA testing also shows promise for the accurate detection of IBD-associated colorectal neoplasms. These findings raise important clinical and translational questions about how to best evaluate and develop this technology, and devise clinical algorithms that will complement colonoscopy to improve patient outcomes.

SummaryBackgroundCurrent approaches to the detection of colorectal neoplasia associated with inflammatory bowel disease (IBD‐CRN) are suboptimal.AimTo test the feasibility of using stool assay of exfoliated DNA markers to detect IBD‐CRN.MethodsThis investigation comprised tissue and stool studies. In the tissue study, gene sequencing and methylation assays were performed on candidate genes using tissue DNA from 25 IBD‐CRNs and from 25 IBD mucosae without CRN. Mutations on p53, APC, KRAS, BRAF or PIK3CA genes were insufficiently informative, but several aberrantly methylated genes were highly discriminant. In the stool study, we evaluated candidate methylated genes (vimentin, EYA4, BMP3, NDRG4) in a prospective blinded study on buffered stools from 19 cases with known IBD‐CRN and 35 age‐ and sex‐matched IBD controls without CRN. From stool‐extracted DNA, target genes were assayed using quantitative allele‐specific real‐time target and signal amplification method.ResultsIBD‐CRN cases included 17 with ulcerative colitis (UC) and two with Crohn's disease (CD); nine had cancer and 10 had dysplasia. Controls included 25 with UC and 10 with CD. Individually, BMP3, vimentin, EYA4 and NDRG4 markers showed high discrimination in stools with respective areas under the ROC curve of 0.91, 0.91, 0.85 and 0.84 for total IBD‐CRN and of 0.97, 0.97, 0.95 and 0.85 for cancer. At 89% specificity, the combination of BMP3 and mNDRG4 detected 9/9 (100%) of CRC and 80% of dysplasia, 4/4 (100%) of high grade and 4/6 (67%) of low grade.ConclusionThese findings demonstrate the feasibility of stool DNA testing for non‐invasive detection of colorectal neoplasia associated with inflammatory bowel disease.