Biopsy depth after radiofrequency ablation of dysplastic Barrett's esophagus

Background: After endoscopic radiofrequency ablation (RFA) of dysplastic Barrett's esophagus (BE), endoscopic biopsy samples are obtained to assess response to therapy. Whether these biopsies are of adequate depth to assess efficacy is unknown. Objective: To compare the depth of endoscopic biopsy samples after RFA with those of untreated controls and to determine the prevalence of subepithelial structures in endoscopic biopsy fragments. Design: Secondary analysis of the AIM Dysplasia Trial, a multicenter, randomized, sham-controlled study. Setting: Nineteen treatment centers. Patients: Subjects with dysplastic BE, either status post RFA or ablation nave (sham). Main Outcome Measurements: The proportion of biopsy samples demonstrating subepithelial structures, stratified by tissue type (columnar vs squamous) in sham- and RFA-treated subjects. Results: A total of 5648 biopsy fragments were analyzed from 113 subjects (78 RFA, 35 sham; mean 50.0 fragments per subject). Most fragments (4653, 82.4%) contained subepithelium. Squamous biopsy samples from RFA and sham subjects demonstrated subepithelium at similar rates (78.4% vs 79.1%, respectively, P = not significant [NS]). Columnar biopsy samples from RFA and sham subjects also included subepithelium at similar rates (99.0% vs 98.8%, respectively, P = NS). Regardless of treatment assignment, more columnar than squamous biopsy samples demonstrated subepithelium (98.8% vs 78.5%, P < .001). Limitations: Biopsy samples were not individually mounted. Conclusions: In both squamous and columnar tissue, endoscopic biopsy samples after RFA were as likely to demonstrate subepithelium as untreated controls. Almost 80% of all biopsy samples were adequate to evaluate for subsquamous intestinal metaplasia. The primary determinant of biopsy depth is the type of epithelium that underwent biopsy, with squamous less likely to yield subepithelium than columnar. Biopsy samples after RFA appear to be of adequate depth to assess response to therapy. (Clinical trial registration number NCT00282672.)