Gastric Adenoma with Low-Grade Dysplasia: Two Countries, Two Outcomes

Abstract

The use of endoscopic submucosal dissection (ESD) for the treatment of gastric neoplasms is rapidly increasing as judged by the large number of publications on the topic (1925 publications 1/1/2000–8/8/2013). Of these 1,925 publications, more than half originate from the countries with a high prevalence of gastric neoplasia such as South Korea and Japan (Fig. 1). To interpret this literature, the reader should know that the indications for ESD differ between two countries: gastric adenomas with either lowgrade dysplasia (LGD) or high-grade dysplasia (HGD) are usually endoscopically resected in Korea, whereas ESD is mostly reserved for early gastric cancers (EGCs) in Japan. This widely different treatment strategy is not related to fundamental differences in the intent of endoscopic therapy or major technical differences between the two countries, but rather due to marked differences in histologic classification, since gastric adenoma with dysplasia diagnosed by a Korean pathologist would be likely diagnosed as an EGC in Japan. In a Korean study performed by Kim et al. [1] reported in this issue of Digestive Diseases and Sciences, complete endoscopic resection revealed that 22 of 285 gastric adenomas initially reported as LGD by endoscopic biopsy were reclassified as having HGD, with 24 lesions reported as adenocarcinomas. They reported that a lesion size C2 cm, the presence of erythema, or depressed lesions were significantly associated with an upgraded histology, consistent with previous Korean studies reporting that EGC diagnosed initially with endoscopic biopsy can be underdiagnosed as LGD [2–5]. Yet, in Japan, where the term ‘‘adenoma with low-grade atypia’’ is used to describe a lesion, concerns might be raised about the endoscopic resection of adenomas with LGD. Although a high incidence of gastric neoplasm exists in Korea and Japan due to the high prevalence of Helicobacter pylori infection, the diagnosis, treatment, and prognosis differ between countries (Fig. 2). Japanese pathologists are reluctant to use the term ‘‘gastric adenoma with LGD’’ because in Japan ‘‘dysplasia’’ connotes ‘‘cancer’’. The term ‘‘adenoma with low-grade atypia’’ has been substituted for ‘‘dysplasia’’ in Japan because the Japanese histological classification of gastric well-differentiated tumors divides intraepithelial gastric neoplasia into adenoma or carcinoma with low and high-grade cytological atypia, unlike the Western criteria [6–9]. From the Japanese viewpoint, gastric adenomas with LGD diagnosed by Western criteria include typical adenomas of the small intestinal type and gastric foveolar type which often have papillary and tubular structures, and thus diagnosed as ‘‘carcinoma without invasion’’ in Japan. Therefore, lesions diagnosed as gastric adenomas in Japan rarely progress to cancer [10], unlike adenomas diagnosed in other countries [11, 12]. In Korea, pathological diagnosis is based on the Western criteria, and thus gastric neoplasia is classified as LGD, HGD, or adenocarcinoma, as reported by Kim et al. [1]. As a consequence, lesions with the same diagnosis are treated differently in Korea and in Japan due to differing histology. The second concern relates to category 4 Vienna classifications for gastrointestinal epithelial neoplasia: 4.1 is HGD, 4.2 is noninvasive carcinoma in situ, and 4.3 is suspicious for invasive carcinoma with intramucosal S.-Y. Lee (&) Department of Internal Medicine, Konkuk University School of Medicine, 120-1 Neungdong-ro, Gwangjin-gu, Seoul 143-729, South Korea e-mail: sunyoung@kuh.ac.kr 1 Institute for Scientific Information Web of Science.