Development of a narrow-band imaging classification to reduce the need for routine biopsies of gastric polyps

Ivor B Asztalos; Caitlin A Colling; Anna M Buchner; Vinay Chandrasekhara

doi:10.1093/gastro/goaa080

Development of a narrow-band imaging classification to reduce the need for routine biopsies of gastric polyps

Gastroenterol Rep (Oxf). 2020 Dec 27;9(3):219-225. doi: 10.1093/gastro/goaa080. eCollection 2021 Jun.

Authors

Ivor B Asztalos¹, Caitlin A Colling², Anna M Buchner³, Vinay Chandrasekhara⁴

Affiliations

¹ Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
² Department of Internal Medicine, Massachusetts General Hospital, Boston, MA, USA.
³ Division of Gastroenterology and Hepatology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.
⁴ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.

Abstract

Background: Most incidental gastric polyps identified during upper endoscopy are considered low-risk. However, current guidelines recommend sampling all gastric polyps for histopathologic analysis. We aimed to devise a simple narrow-band imaging (NBI) classification to reduce the need for routine biopsies of low-risk gastric polyps.

Methods: Pairs of NBI and white-light images were collected from 73 gastric polyps for which concurrent histopathologic diagnosis was available. A diagnostic accuracy cohort study was performed. Two blinded endoscopists independently analysed NBI features of each polyp for color, vessel pattern, surface pattern, and any combinations thereof to develop a classification scheme to differentiate low-risk polyps (fundic-gland or hyperplastic) from high-risk polyps (adenomatous or adenocarcinoma) and fundic-gland polyps (FGPs) from non-FGPs.

Results: An isolated lacy vessel pattern and a homogenous absence of surface pattern successfully differentiated low-risk from high-risk gastric polyps. Combining both descriptors into a single algorithm resulted in a negative predictive value (NPV) of 100% [95% confidence interval (CI): 100%-100%], positive predictive value (PPV) of 13.7% (95% CI: 2.6-24.8), sensitivity of 100% (95% CI: 100%-100%), and specificity of 53.7% (95% CI: 45.3%-62.0%) for high-risk polyps. This would reduce the number of polyps requiring biopsy by 50%, while still capturing all high-risk polyps. Regarding FGPs, using a rule not to biopsy polyps with isolated lacy vessels resulted in a 94.9% NPV (95% CI: 89.2%-100%), 63.2% PPV (95% CI: 47.2%-79.2%), 94.8% sensitivity (95% CI: 89.5%-100%), and 63.6% specificity (95% CI: 51.3%-76.0%) for non-FGPs.

Conclusion: In this derivation cohort study, NBI is helpful for differentiating between high-risk and low-risk gastric polyps, thereby reducing the need for routine sampling of low-risk polyps. These results need to be validated in a separate test population.

Keywords: endoscopy; gastric cancer; gastric polyps; malignancy; narrow-band imaging.