Background: Real time visual differentiation of colorectal polyps into benign and malignant helps to decide the appropriate treatment strategy and avoid the unnecessary risk associated with endoscopic therapies and need for repeat procedures. The Japan NBI Expert Team (JNET) classification developed in 2014 classifies colorectal polyps into types 1(Hyperplastic polyps including sessile serrated polyps), 2A (low grade dysplasia), 2B (high grade dysplasia/ superficial submucosal invasive carcinomas) and 3 (deep submucosal invasive carcinomas). We conducted this study to evaluate the diagnostic accuracy of the JNET classification for colorectal polyps.
Methods: All patients undergoing colonoscopy in a tertiary care Centre in south India from February to July 2020, who had colorectal polyps were included in the study. A prospective image evaluation to identify the JNET class was done by 2 independent observers blinded to the histological diagnosis and the result was compared with the final histopathological diagnosis. Inflammatory polyps were excluded. The collected data was statistically analyzed to assess the diagnostic accuracy.
Result: 139 polyps from 102 patients were included in the study. Most common locations were ascending colon (31%) or rectosigmoid (30.3%). 21 polyps were hyperplastic polyps, 78 polyps were LGD, 23 were HGD/SM-S and 17 were SM-D polyps. On NBI imaging, 23, 76, 30, and 10 polyps were classified as JNET types 1, 2a, 2b and 3 respectively. The diagnostic accuracy of JNET classification was 98.5%, 88.4%, 83% and 93.5% respectively.
Conclusion: The JNET classification has a high diagnostic accuracy for predicting the histology of colorectal polyps and hence recommended.