早期胃癌の自然史に関する前向き研究―胃癌診療への考察

Prospective Study of Early Gastric Cancer, with Considerations Concerning Clinical Practice for Gastric Cancer

要旨　早期胃癌の自然史を明らかにするため，内視鏡で早期胃癌，病理学的に癌と診断されながら，切除されなかったか，切除が診断から6か月以上遅れた症例を検索し，それより同定した80例の前向き研究を行った．病巣の経過観察は61例において可能であった．早期胃癌が進行癌に進展する割合は次第に増加し，44か月までに50％が進行癌に進展した．5年累積進展率は64.7％であった．46例においては胃癌切除が実施されなかった．胃癌で死亡した場合と死因不明例を“死亡"，他の原因で死亡した場合を“生存打ち切り"として，非切除早期胃癌の生存率を算出した．5年累積生存率は60.5％であった．早期胃癌の大多数は“癌もどき"でなく，放置すれば進行癌に進展し，やがては胃癌死すると結論した．

　To elucidate the natural history of early gastric cancer（EGC）, a non-concurrent, follow up study was conducted in 80 patients who were diagnosed endoscopically as EGC, which was confirmed as cancer on biopsy, but in whom surgical resection was not conducted or was delayed by more than six months. The natural course of EGC was observed in 61 cases. The proportion of those who progressed to the advanced stage increased consistently with time. Median duration of those who progressed to the advanced stage was estimated as 44 months. The cumulative five year risk for progressing to the advanced stage was 64.7％. In 46 cases there was no evidence for undergoing surgical resection for gastric cancer. The cumulative five year corrected survival was estimated as 60.5％ among those unresected. We conclude that most EGCs are not a pseudo-cancer ; they progress to the advanced stage with time and lead to death from gastric cancer if left untreated.