Optical diagnosis of colorectal lesions requires technology, dedication, and knowledge of its limits

FIT fecal immunochemical testing NBI narrow band imaging NICE NBI International Colorectal Endoscopic PIVI Preservation and Incorporation of Valuable Endoscopic Innovations Optical diagnosis of small colorectal polyps without the need for histopathology has the potential to improve the cost effectiveness of colonoscopy by reducing the time for polyp retrieval and the cost of histopathology [1,2]. In addition, the ability to tell patients the surveillance interval needed immediately after the procedure reduces the cost associated with follow-up and alleviates patient anxiety. Many studies, including several meta-analyses [3–5], have shown that optical diagnosis of small colorectal polyps is safe and feasible in routine clinical practice and that the results are comparable to those found using histopathology, the current reference standard. In academic centers and in vivo settings, experienced endoscopists have achieved 93% concordance of surveillance intervals neededwhenmade by optical diagnosis and histopathology and>90% negative predictive value for rectosigmoid polyps. Because the risk of malignancy increases with the size of the polyp (>1cm), most studies have focused on evaluating the accuracy of optical diagnosis of smaller polyps (<10mm). Americans, however, are uncomfortable with even the small risk of advanced malignancy that 6–9mm polyps may harbor and tend to concentrate on diagnosis of diminutive polyps (<6mm). The American Society of Gastrointestinal Endoscopy Preservation and Incorporation of Valuable Endoscopic Innovations established diagnostic thresholds for real time endoscopic assessment of the histology of diminutive colorectal polyps to facilitate standardized research and implementation in clinical practice [6]. There are two proposed thresholds for optical diagnosis of diminutive colorectal polyps: 1. For colorectal polyps≤5mm to be resected and discarded without histopathologic assessment, endoscopic technology (used with high confidence) to determine histology combined with histopathologic assessment should provide a≥ 90% agreement in the assignment of post-polypectomy surveillance intervals when compared to decisions based on pathology assessment of identified polyps. 2. For a technology to be used to guide the decision to leave suspected rectosigmoid hyperplastic polyps≤5mm in place (without resection), the technology (used with high confidence) should provide≥90% negative predictive value for adenomatous histology. The study by Stegeman et al published in this Issue failed to fulfill the second criterion (the first criterion was not assessed) and the authors concluded that the accuracy of optical diagnosis for colonic lesions is not acceptable for colonoscopies for patients with positive fecal immunochemical testing (FIT) results. Their study highlights many issues with the studies of optical diagnosis and the conclusions drawn.