Endoscopic resection of Barrett's adenocarcinoma: Intramucosal and low-risk tumours are not associated with lymph node metastases

Background Superficial oesophageal adenocarcinoma can be resected endoscopically, but data to define a curative endoscopic resection are scarce. Objective Our study aimed to assess the risk of lymph node metastasis depending on the depth of invasion and histological features of oesophageal adenocarcinoma. Methods We retrospectively included all patients undergoing an endoscopic resection for T1 oesophageal adenocarcinoma among seven expert centres in France in 2004-2016. Mural invasion was defined as either intramucosal or submucosal tumours; the latter were further divided into superficial submucosal (<= 1000 mu m) and deep submucosal (>1000 mu m). Absence or presence of lymphovascular invasion and/or poorly differentiated cancer (G3) defined a low-risk or a high-risk tumour, respectively. For submucosal tumours, invasion depth and histological features were systematically confirmed after a second dedicated histological assessment (new 2-mm thick slices) performed by a second pathologist. Occurrence of lymph node metastasis was recorded during the follow-up from histological or PET CT reports when an invasive procedure was not possible. Results In total, 188 superficial oesophageal adenocarcinomas were included with a median follow-up of 34 months. No lymph node metastases occurred for intramucosal oesophageal adenocarcinomas (n=135) even with high-risk histological features. Among submucosal oesophageal adenocarcinomas, only tumours with lymphovascular invasion or poorly differentiated cancer or with a depth of invasion >1000 mu m developed lymph node metastasis tumours (n=10/53; 18.9%; hazard ratio 12.04). No metastatic evolution occurred under a 1000-mu m threshold for all low-risk tumours (0/25), nor under 1200 mu m (0/1) and three over this threshold (3/13, 23.1%). Conclusion Intramucosal and low-risk tumours with shallow submucosal invasion up to 1200 mu m were not associated with lymph node metastasis during follow-up. In case of high-risk features and/or deep submucosal invasion, endoscopic resections are not sufficient to eliminate the risk of lymph node metastasis, and surgical oesophagectomy should be carried out. These results must be confirmed by larger prospective series.