Poor Interobserver Agreement in the Distinction of High-Grade Dysplasia and Adenocarcinoma in Pretreatment Barrett's Esophagus Biopsies

Abstract

Grading Barrett's dysplasia at the lower end of the metaplasia-dysplasia spectrum (negative, indefinite, and low-grade dysplasia) suffers from poor interobserver agreement, even among gastrointestinal pathologists. Data evaluating interobserver agreement in Barrett's mucosal biopsies with changes at the upper end of the dysplasia spectrum (high-grade dysplasia, intramucosal, and submucosal adenocarcinoma) have not been published. The accurate categorization of pretreatment biopsies drives therapeutic decision making, but if the diagnostic distinction between cancer and high-grade dysplasia in Barrett's biopsies is inconsistent, then the use of these diagnoses to make management decisions is suspect. To this end, our aim was to assess interobserver reproducibility among a group of gastrointestinal pathologists in the interpretation of preresection biopsies. All study pathologists agreed upon the histologic criteria distinguishing four diagnostic categories, including high-grade dysplasia; high-grade dysplasia with marked distortion of glandular architecture, cannot exclude intramucosal adenocarcinoma; intramucosal adenocarcinoma; and submucosally invasive adenocarcinoma. The histologic criteria were used to independently review preresection biopsies from 163 consecutive Barrett's esophagus patients with at least high-grade dysplasia who ultimately underwent esophagectomy. Reviewers recorded the specific histologic criteria used to categorize each case and Kappa statistics were calculated to assess interobserver agreement. Using kappa statistics, the overall agreement was only fair (kappa= 0.30). Agreement for high-grade dysplasia was moderate (kappa= 0.47), while agreement for high-grade dysplasia with marked architectural distortion, cannot exclude intramucosal adenocarcinoma and intramucosal adenocarcinoma were only fair (kappa= 0.21 and 0.30, respectively) and agreement for submucosal adenocarcinoma was poor (kappa= 0.14). The overall poor interobserver reproducibility among gastrointestinal pathologists who see a high volume of Barrett's cases calls into question treatment regimens based on the assumption that high-grade dysplasia, intramucosal adenocarcinoma, and submucosal adenocarcinoma can reliably be distinguished in biopsy specimens.