Measuring the Submucosal Depth of Invasion in Endoscopic Mucosal Resections for Barrett-associated Adenocarcinoma: Practical Issues and Relevance for the Decision for Esophagectomy.

Abstract

Endoscopic mucosal resection (EMR) has made it possible for Barrett esophagus patients with superficial cancers to be treated without esophagectomy. Recent guidelines recommend measuring depth of invasion (DOI) in submucosal cancers based on reports that in low-risk cancers, submucosal invasion 500 μm or less is associated with low nodal metastasis rates. However, pathologists face challenges in reproducibly measuring DOI. To determine how often DOI measurements could impact treatment and to evaluate reproducibility in measuring submucosal DOI in EMR specimens. Consecutive adenocarcinoma EMR cases were identified, including cases of "low histologic risk" submucosal cancer, as follows: those with negative deep margins, no high-grade histology (G3), and no lymphovascular invasion. Submucosal DOI was measured by 7 pathologists according to guidelines. Of 213 cancer EMR cases, 46 were submucosa invasive and 6 cases were low histologic risk submucosal cancers for which measurement could impact decision-making. Of these low histologic risk cases, 3 were categorized as superficial, indicating that measurement would be a clinically actionable decision point in only 1.4% of adenocarcinoma EMRs. Interobserver agreement for in-depth categorization between 7 pathologists was moderate (κ = 0.42), and the range of measurements spanned the 500-μm relevant threshold in 40 of 55 measured samples (72.7%). While therapeutic decisions would rarely have depended on DOI measurements alone in our cohort, interobserver variability raises concerns about their use as a sole factor on which to offer patients conservative therapy. Responsibly reporting and clinically using submucosal DOI measurements will require practical experience troubleshooting common histologic artifacts, as well as multidisciplinary awareness of the impact of variable specimen-handling practices.