食道胃接合部病変の疫学

Epidemiology of disorders involving the esophagogastric junction

要旨

本邦の食道胃接合部病変は，Helicobacter pylori感染率の低下や人口の高齢化に伴い，従来の萎縮性胃炎中心の病態から，胃食道酸逆流や食道運動異常を主体とする病態へと大きく変化している。現在，胃食道逆流症の有病率は頭打ちの状態にあるが，高齢者の円背や横隔膜の脆弱化による食道裂孔ヘルニアは，依然として重要なリスク因子である。また，食道胃接合部癌は食道癌全体の約8.5％を占めるまでに至っており，欧米に多いlong-segment Barrett’s esophagus由来とは異なり，本邦ではshort-segment Barrett’s esophagus（SSBE）由来が中心であるという特有の性質をもつ。さらに，食道アカラシアにおいては，診断技術の向上や経口内視鏡的筋層切開術の普及により，潜在的な患者層が顕在化し，有病率の再定義が進んでいる。2026年現在の食道胃接合部病変の診療においては，SSBEからの微小腺癌の的確な形態診断・治療だけでなく，下部食道括約部の運動異常を考慮した機能診断・治療が，消化器専門医にとって不可欠な課題となっている。

　In Japan, the landscape of esophagogastric junction (EGJ) lesions has undergone a significant paradigm shift. Due to declining Helicobacter pylori infection rates and an aging population, the primary pathophysiology has moved away from traditional atrophic gastritis toward conditions dominated by gastroesophageal reflux and esophageal motility disorders. While the prevalence of gastroesophageal reflux disease appears to have plateaued, hiatal hernia-driven by age-related kyphosis and diaphragmatic weakening-remains a critical risk factor. Furthermore, esophagogastric junction adenocarcinoma now accounts for approximately 8.5% of all esophageal cancers. Notably, unlike the long-segment Barrett’s esophagus cases prevalent in Western countries, Japan exhibits a unique characteristic where short-segment Barrett’s esophagus （SSBE） serves as the primary origin. Regarding esophageal achalasia, the emergence of improved diagnostic techniques and the widespread adoption of peroral endoscopic myotomy have brought previously undiagnosed cases to light, leading to a redefinition of its prevalence. As of 2026, the management of EGJ lesions requires gastrointestinal specialists to master two essential challenges: “morphological diagnosis and treatment of minute adenocarcinomas arising from SSBE” and “functional diagnosis and treatment that account for motility abnormalities of the lower esophageal sphincter.”