2022 消化系聯合學術演講年會
外賓演講（三） PRESENT AND FUTURE PERSPECTIVES OF ENDOSCOPIC DIAGNOSIS AND TREATMENT FOR EARLY GASTRIC CANCER Mitsuhiro Fujishiro The University of Tokyo, Japen
Gastric cancers are still one of the major causes of cancer death worldwide. Although the situation is the same in Japan, age-adjusted incidence and mortality of gastric cancer are consistently decreasing year by year in Japan. These trends mainly depend on the decrease of Helicobacter pylori (HP) infected patients, mass-screening of gastric cancer, and wide spread use of upper GI endoscopy. In terms of endoscopic diagnosis of early gastric cancers, white light image (WLI) is still the gold standard for detection of gastric cancer and optical digital method such as NBI, BLI, and OE with the combined use of magnifying endoscope is now widely used for characterization of gastric cancer. Magnifying endoscopy simple diagnostic algorithm for early gastric cancer (MESDA-G) was established in cooperation with the Japanese Gastroenterological Association, Japan Gastroenterological Endoscopy Society, and the Japanese Gastric Cancer Association (Muto M, et al. Dig Endosc. 2016;28:379-93). If we detect a suspicious lesion, identification of a demarcation line (DL) between the lesion and the background mucosa is the first step in distinguishing gastric cancer from a noncancerous lesion. If a DL is absent, the diagnosis of a benign lesion may be made. If a DL is present, the subsequent presence of an irregular microvascular (MV) pattern and an irregular microsurface (MS) pattern should be determined. If irregular MV and/or MS patterns are present within the demarcation line, the diagnosis of gastric cancer can be made. Furthermore, in terms of MV pattern, majority of differentiated type cancers show fine
network pattern and majority of undifferentiated type cancers show corkscrew pattern or wavy microvessels, which is useful to predict histological type of early gastric cancer. Recently, endocytoscope (ECS) is commercially available, which enables us to make the target lesions as no, mild and severe atypia in cells and structures (Kaise M, et al. Endoscopy 2014; 46: 827–832). Additionally, artificial intelligence is also in progress for diagnosis of early gastric cancer (Hirasawa T, et al. Gastric Cancer. 2018; 21:653-660). Strategy of endoscopic treatment of early gastric cancers is based on the guidelines endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer (second edition) (Ono H, et al. Dig Endosc. 2021;33:4-20) and Japanese gastric cancer treatment guidelines 2021 (6th edition). Based on the open data No.4 by National Database in Japan, 54,742 cases of gastric cancers are treated by endoscopic resection in Japan, which accounts for 41% of the total gastric cancers. Majority of the cancers are treated by ESD, which is a method whereby the mucosa surrounding the lesion is excised using a high-frequency diathermy device, followed by dissection of the submucosa beneath the lesion. By using ESD, technical hurdles have been nearly overcome in terms of size, location, fibrosis, and morphology of the lesions. Endoscopic resection, either EMR or ESD, is absolutely indicated in ‘clinically intramucosal (cT1a) differentiated carcinomas measuring less than 2 cm in diameter. The macroscopic type does not matter, but there must be no finding of ulceration (scar);
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