Inter-Observer Variability in the Interpretation of Endoscopic Mucosal Resection Specimens of Esophageal Adenocarcinoma: Interpretation of ER specimens

Introduction: Endoscopic resection (ER) has revolutionized the staging and therapy of superficial esophageal adenocarcinoma. Pathologic evaluation allows an assessment of the risk of lymph node metastases based on tumor characteristics. The aim of this study was to assess the inter-observer variability in pathologic assessment of ER specimens of esophageal adenocarcinoma.

Methods: We performed a retrospective study on ER specimens of superficial esophageal adenocarcinoma from four US institutions. Original endoscopic resection slides were re-reviewed by two blinded, experienced (study) gastrointestinal pathologists for the depth of tumor invasion, tumor grade, and the presence of lymphovascular invasion (LVI). Discordance was considered present only when both study pathologists disagreed with the original report.

Results: There were 25 ER specimens reviewed for this study, and discordance occurred in 12 of the 25 specimens (48%) for the depth of tumor invasion. In most cases (83%), the discordance was related to overstaging a true T1a lesion. We found that only 38% of true T1a lesions were correctly staged for depth of invasion. Less commonly discordance was secondary to understaging a true T1b lesion. There was concordance between the two study pathologists in 22/25 cases (88%) on the depth of invasion. Discordance was present for tumor grade in 8/18 cases (44%) and for LVI in 4/16 cases (25%). Concordance between the study pathologists was 80% for tumor grade and 88% for LVI.

Conclusions: There was an alarmingly high rate of discordance (48%) between the study pathologists and the original pathology assessment for the depth of tumor invasion in ER specimens. This was particularly common for lesions called T1b on the original pathology report. Since critical decisions are made regarding esophageal preservation or esophagectomy on the basis of the pathologic interpretations of ER specimens, it behooves surgeons to understand the inter-observer variability. Review of ER specimens by an experienced GI pathologist is recommended to ensure that patients receive the appropriate treatment for superficial esophageal adenocarcinoma.