222. ARE GASTRIC MAPPING BIOPSIES NECESSARY TO DETERMINE THE DISTAL RESECTION MARGIN FOR SIGNET RING ADENOCARCINOMAS OF THE OESOPHAGO-GASTRIC JUNCTION?

Abstract

Abstract In our department patients with oesophago-gastric junctional adenocarcinomas with signet ring differentiation undergo a second endoscopy for gastric mapping biopsies to investigate the extent of tumour extension into the proximal stomach. This is due to the perceived aggressive morphology and to avoid a R1 (microscopic positive) resection at the distal margin. Our aim was to elucidate whether gastric mapping endoscopic biopsies are necessary prior to resection in signet ring adenocarcinomas of the oesophago-gastric junction (OGJ). Patients with operable OGJ adenocarcinomas with signet ring morphology were retrospectively analysed from 2011–2021 from our databank of completed oesophagectomies at our upper gastrointestinal cancer surgical department. From 2014–2021, OGJ adenocarcinomas identified with signet ring differentiation were subjected to a second invasive endoscopy with gastric mapping biopsies to determine the distal ex-tent of microscopic invasion into the cardia and beyond. These were analysed to determine the histopathological yield from gastric mapping biopsies and the number of cases with a positive (R1) distal resection margin. From 2014, 322 oesophagectomy cases were completed and these were analysed further. Of these, 21.7% (n = 70) were found pre-operatively to have signet ring differentiation and thus underwent a second gastric mapping endoscopy. Within the signet ring morphology cohort, only one patient (1.4%) was found to involve a R1 resection margin which necessitated a second operation involving gastric resection and colonic interposition. Our results suggest that patients with signet ring adenocarcinoma of the OGJ do not need gastric mapping biopsies to determine the distal margin prior to resection. Although considered a more aggressive subtype of adenocarcinoma, radial infiltration from the tumour does not seem to affect conventional surgical oncological margins.