Helicobacter pyloriと未分化型胃癌―Hp分布と未分化型癌が発生する粘膜環境の検討

Helicobacter pylori and Undifferentiated Type Gastric Adenocarcinoma, Distribution of Hp and Environment of Mucosa

要旨　未分化型胃癌発生とHpとの関連を考察するため，Hpの胃内分布を胃全摘材料を用い，鏡検および定量的PCRにより検索した．Hp感染は腸上皮化生のない粘膜に広くみられたが，その分布は一様ではなかった．①化生・非化生上皮が混在する部分で菌量は少なく，②腸上皮化生のない領域で菌量は多いが，③腺境界から離れ大彎・胃底部に近づくと非感染領域が混在，菌量が減少し，④腸上皮化生のない大彎・胃底部でもHp感染がない症例がみられた．スキルス癌の初期像と考えられる超微小印環細胞癌の多くが，少量のHp感染を伴う，腸上皮化生のない粘膜を背景としたのに対し，進行した未分化型癌は腸上皮化生が混在し，比較的Hp量の多い領域にみられた．以上を合わせてHp感染域は腺境界・小彎から大彎側へ向かって拡大すると考えられ，多くの未分化型癌は，拡大するHp感染の先進領域で発生している可能性が示唆された．

　To investigate the relationship between Helicobacter pylori (Hp) and the development of undifferentiated type gastric adenocarcinoma, we evaluated Hp infection in serially cut total gastrectomy specimens quantitatively, using histopathological and Real-time polymerase chain reaction technique. Hp infection was widely distributed in the mucosa without intestinal metaplasia but the grade of infection was not uniform. In mixed areas of metaplasitc and non-metaplastic epithelium, the grade of infection was slight to modearate and the highest grade of infection was observed in the areas without intestinal metaplasia. In the non-metaplastic area, the grade of infection gradually reduced toward the greater curvature and some cases with non-infected areas in the greater curvature and/or gastric fundus were found. The majority of "ultra-small signet ring cell carcinomas were located in the mucosa with characteristics of slight Hp infection and no intestinal metaplasia. On the other hand, advanced undifferentiated cancers were located in the areas with intestinal metaplasia and moderate to high grade Hp infection. These findings suggest that, Hp infected areas spread from the border of the fundic /pyloric gland toward the greater curvature, While the majority of undifferentiated type gastric cancers may originate from the front-line areas of spreading Hp infection.