Prospective comparison of diagnostic performance of magnifying endoscopy and biopsy for sessile serrated adenoma/polyp

BACKGROUND: Magnifying narrow-band imaging (M-NBI) has recently improved the accuracy of endoscopic diagnosis of gastrointestinal tumors, including colorectal polyps. However, it can be difficult to distinguish between sessile serrated adenoma/polyps (SSA/Ps) and other polyps, especially hyperplastic polyps (HPs), by histological biopsy, because diagnostic features of SSA/Ps can be detected around the colon crypt bases. We aimed to evaluate the accuracy of endoscopic diagnosis of SSA/Ps using M-NBI compared with histological biopsy. METHODS: We prospectively enrolled patients diagnosed with SSA/Ps by preoperative endoscopy and assessed the diagnostic accuracy. The primary outcome was the diagnostic accuracy of endoscopy and biopsy. RESULTS: Between August 2015 and October 2017, 295 lesions were resected by polypectomy or endoscopic mucosal resection, and 79 endoscopically resected specimens that were endoscopically diagnosed as SSA/P underwent biopsy for histological examination. Two lesions were excluded because the specimens were too small for histological examination. Finally, 77 endoscopically resected specimens and 77 biopsy specimens were included in the analysis. Histopathological examination showed 67 SSA/Ps, 8 HPs, and 2 adenomas. The sensitivity, specificity and accuracy of endoscopic M-NBI diagnosis for SSA/Ps were 95.7%, 95.5% and 95.6%, respectively. The sensitivity, specificity and accuracy of histological diagnosis of a single biopsy specimen were 71.6%, 90.0% and 74.0%, respectively. The McNemar test showed significant differences between biopsy and endoscopy diagnoses (P=0.001). CONCLUSION: This study shows that biopsy may be avoided by using M-NBI in patients with suspected SSA/Ps.