Helicobacter pyloriと噴門部癌

The Role of H. pylori Infection in the Adenocarcinoma of Gastric Cardia

要旨　噴門部癌はBarrett腺癌とともに欧米で増加が報告されており，その病態には胃食道逆流症が強く関連し，H. pylori感染の関与は少ないと考えられている．しかし，噴門部癌の定義は必ずしも統一されておらず，H. pylori感染率および背景となる胃粘膜の胃炎様式，胃食道逆流症の頻度や程度などの大きな地域差も考慮する必要があり，H. pylori感染と噴門部癌の関連については未解決の部分が多い．本邦ではBarrett腺癌，噴門部癌いずれも頻度は低く，多数例での検討は困難な状況であるが，われわれの限られた検討では，噴門部癌は通常の非噴門部胃癌と同様，H. pylori感染による高度の胃粘膜萎縮，低酸状態を背景とするものの他に，H. pylori感染によらず胃酸分泌が十分維持されているもの，すなわちBarrett腺癌類似の病態を示すものが存在すると推測された．

　The Adenocarcinoma of Barrett's esophagus and gastric cardia is increasing in Western countries. It has been shown that the pathogenesis of these malignancies is more closely associated with gastroesophageal reflux disease than with the inflammation induced by H. pylori infection at the gastroesophageal junction. However, these two entities are not uniformly defined through previous studies and it is often difficult to distinguish one from the other clearly in clinical settings. Furthermore, we need to consider that there is much difference in the prevalence of H. pylori infection, the pattern of its induced gastritis and the status of gastroesophageal reflux diseases in respective geographic areas. It is generally understood in Japan that most cardiac cancer is related with severe atrophic gastritis and subsequent gastric hyposecretion by H. pylori infection as well as distal gastric cancer, but our limited study has suggested that a certain subset of it may be linked with the preservation of gastric acid secretion rather than with the presence or absence of H. pylori infection.