ピロリ陽性だとどれくらい胃癌発癌の危険率が高まるのか？ 16年間のコホート

和歌山県立医科大学グループの論文です。
 
Int J Cancer 

Cancer development based on chronic active gastritis and resulting gastric atrophy as assessed by serum levels of pepsinogen and Helicobacter pylori antibody titer

Takeichi Yoshida, Jun Kato, and others, and Toshikazu Ushijima, Masao Ichinose 

Article first published online: 3 OCT 2013

Our study investigated the relationship between gastric cancer development and activity of Helicobacter pylori-associated chronic gastritis or the resulting chronic atrophic gastritis (CAG). A cohort of 4,655 healthy asymptomatic subjects, in whom serum pepsinogen (PG) and H. pylori antibody titer had been measured to assess the activity and stage of H. pylori-associated chronic gastritis, was followed for up to 16 years, and cancer development was investigated. In subjects with a serologically diagnosed healthy stomach (H. pylori-negative/CAG-negative), cancer incidence rate was low, at 16/100,000 person-years. With the establishment of H. pylori infection and progression of chronic gastritis, significant stepwise cancer risk elevations were seen from 

1. CAG-free subjects (H. pylori-positive/CAG-negative) [hazard ratio (HR) = 8.9, 95% confidence interval (CI) = 2.7–54.7] to 
   
2. subjects with CAG (H. pylori-positive/CAG-positive) (HR = 17.7, 95% CI = 5.4–108.6) and finally to 
   
3. subjects with metaplastic gastritis (H. pylori-negative/CAG-positive) (HR = 69.7, 95% CI = 13.6–502.9). 

In H. pylori-infected CAG-free subjects, significantly elevated cancer risk was observed in the subgroup with active inflammation-based high PG II level or potent immune response-based high H. pylori antibody titer; the former was associated with a particularly high risk of diffuse-type cancer, and both subgroups showed high cancer incidence rates of around 250/100,000 person-years, comparable to that in subjects with CAG. No such risk elevation was observed in H. pylori-infected subjects with CAG. These results clearly indicate that gastric cancer develops mainly from the gastritis-atrophy-metaplasia-cancer sequence and partly from active inflammation-based direct carcinogenesis, and that serum levels of PG and H. pylori antibody titer provide indices of cancer development in H. pylori-infected subjects.

小生が外来でピロリ陽性で除菌をしているのは、もっぱら老人壮年である。じつに空しいが小生なんとか頑張ってやっているのだ。（これまで何十年も陽性だったのだから、除菌を機に一挙にカメラ検診をやめるわけにはいかないからね、だから空しい）

若者よ我が外来にいらっしゃい。ピロリ陽性の若者を除菌したとき、初めて日本から胃癌が減るのだから。

ピロリ陽性が少なくなったとはいえ、君たちこそ真の除菌対象群なのだから。