Mo1917 The Prague Classification Underestimates the True Maximal Extent and Dysplasia Grade of Barrett's Esophagus

Abstract

Background: Endoscopic treatment by either radiofrequency (RFA) ablation or endoscopic mucosal resection (EMR) has become first line treatment for Barrett's esophagus (BE) with high grade dysplasia, while focal EMR and subsequent elimination of the residual segment by RFA or EMR is accepted therapy for intramucosal cancer (IMC). RFA and EMR are known to be clinically effective but the effect on the mRNA expression of molecular markers of disease stage, which may inform the long term risk of progression to adenocarcinoma, is unknown. We compared the mRNA expression profile in pre-treatment BE tissues biopsies and post-treatment neo-squamous tissues from the same level to provide a surrogatemolecular estimate of treatment effect. Methods: Paired pre-treatment BE tissues and post-treatment neosquamous biopsies were obtained from 38 patients treated by RFA (20 patients (3 IMC (prior EMR), 5 HGD, 12 LGD) or EMR (18 patients, 6 IMC, 12 HGD). mRNA expression of 16 genes significantly associated with different BE stages was measured using a multiplex tandem RT-PCR method with preand post-treatment tissues assessed simultaneously. Distal esophageal tissues from 12 patients with no history of GERD or BE were used as controls. Results: Endoscopic therapy resulted in a highly significant change in median values towards the squamous mucosa expression profile for all 16 genes on unpaired analysis. This change remained significant for 12 genes by paired analysis (t test). The only significant treatment differences in pre-post mean difference in gene expression were greater changes for RFA compared to EMR for 5 genes. The neosquamous expression profile was significantly different to the control profile for 9 of 16 genes. Conclusions: Both RFA and EMR result in marked changes in mRNA expression, with replacement of the highly disordered Barrett's dysplasia or IMC expression profile with a more normal expression profile. The neosquamous mucosa was significantly different to the control squamous mucosa for most genes but the significance of this finding is uncertain and may reflect confounding factors.