Post written by Seiichiro Abe, MD, PhD, from the Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan.

Endoscopic resection (ER) is a minimally invasive treatment option for superficial adenocarcinoma (EA). We recently demonstrated that lymphovascular involvement, a poorly differentiated histology, and lesion size were independent risk factors for metastasis in patients with esophageal adenocarcinoma. Patients with mucosal and slight submucosal (SM) cancers (1–500 μm) without these risk factors were unlikely to have lymph node metastasis and therefore ideal candidates for ER (Ishihara R, et al. J Gastroenterol. 2016). The aim of this study was to clarify the long-term outcomes in Japanese patients with adenocarcinoma of the esophagogastric junction (AEGJ) after ER based on our criteria for the risk of lymph node metastasis. This study also evaluated the occurrence of metachronous AEGJ after ER in Japanese population.

A total of 372 patients undergoing ER were included from 13 referral institutions. A total of 277 patients were low-risk and 95 were high-risk for lymph node metastasis. Five-year cumulative incidences of local recurrence were 13% and 0.5% in the EMR and ESD group, respectively (P<0.01). The 5-year overall survival and disease specific survival rates in patients who met our risk criteria were 93.9% and 100%, respectively. The 5-year cumulative incidence of metachronous EA in 316 patients without additional treatment was 1.1%.

This study supports the proposed risk criteria could be applied into the clinical practice for endoscopic resection of AEGJ. The incidence of metachronous lesions was as high as 15-30% within a follow-up period of 3 years in the West. However, the 5-year cumulative incidence of metachronous AEGJ in our study was only 1.1%. This discrepancy could be explained by significant differences in length of Barrett’s esophagus, the length of SSBE (mainly ultra-short in Japan), and the definitions of metachronous lesion.

There is a difference in treatment options and availabilities between Japan and Western countries. EMR followed by radiofrequency ablation is the standard of care to treat any suspicious area for EA or high-grade dysplasia and the remaining BE in Western countries. However, radiofrequency ablation is not commercially available in Japan. Therefore, prophylactic treatments for the remaining BE at risk for metachronous lesions are rarely performed in our population. Given the high success rate of en bloc and R0 of ESD and lower incidence of local and metachronous lesions in Japan, ER alone is considered to be an  acceptable and effective treatment among the Japanese gastroenterologists. The results of our study suggested that completeness of resection of the primary AEGJ and precise assessment of the histology by the index ESD was essential in patients with AEGJ in Japanese patients. In this study, favorable long-term outcomes with ER were observed in patients who met the low-risk criteria. ESD is a preferred method of treatment for superficial EA in Japanese patients.

Figure 1. Chronologic trends of numbers of EMR and ESD. An increase in ESD cases and a decrease in EMR cases were observed overtime. ESD, Endoscopic submucosal dissection.

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