Surveillance for pathology associated with cancer on endoscopy (SPACE): criteria to identify high-risk gastric polyps in familial adenomatous polyposis

Abstract

Background and aims: Gastric cancer is an extracolonic manifestation of familial adenomatous polyposis (FAP) and is associated with high-risk gastric polyps. There are no known endoscopic criteria to identify these high-risk polyps. Our aim was to develop endoscopic criteria to identify high-risk polyps on endoscopy in FAP.

Methods: We prospectively collected 150 gastric polyps in consecutive patients undergoing surveillance EGD at the Cleveland Clinic. Pictures were taken of each polyp under narrow-band imaging and high-definition white light. In an exploratory phase, 5 endoscopists developed consensus criteria using the images to distinguish high-risk (pyloric gland adenoma, tubular adenoma, hyperplastic) from low-risk (fundic gland with low-grade or no dysplasia) polyps. In the assessment phase, endoscopists were blinded to polyp pathology and used the criteria to predict the individual polyp risk category. To measure diagnostic accuracy, we reported the mean sensitivity, specificity, and interrater agreement (κ).

Results: Consensus criteria were developed based on 16 low-risk and 9 high-risk polyps. The final 149 polyps consisted of 128 low-risk and 22 high-risk polyps (1 polyp was excluded from analysis). Using the criteria, the 5 endoscopists distinguished high- from low-risk polyps with a mean sensitivity and specificity of 79% (16.3%) and 78.8% (10.8%), respectively. The κ coefficient was .45, indicating moderate agreement.

Conclusions: We developed endoscopic criteria to distinguish between high- and low-risk polyps associated with gastric cancer in FAP. The criteria provide guidance to endoscopists in targeting high-risk polyps while surveying the stomach of patients with proximal gastric polyposis.