内視鏡経過観察例からみた胃癌ハイリスクグループ

Predicting the Development of Gastric Cancer from Initial Endoscopic Findings : A Prospective Cohort Study

要旨　わが国においてX線検診に加えて内視鏡胃癌検診が開始されたが，費用対効果の面から問題があり，対象集約が必要と考えられる．初回検査から3年以内の間隔で追跡内視鏡検査を3,672名に実施し，胃癌81例（2.2％：男性57例，女性24例）を発見した．初回検査から発見までの期間は3年未満24例，3年以上6年未満26例，6年以上31例であった．男性発見率は女性より高く，8年累積発見率は3.9％であった．55歳以上の発見率は54歳以下より高く，8年累積発見率は4.4％であった．粘膜萎縮が中程度以上群の発見率は萎縮軽度・なし群より高く，8年累積発見率は8.1％であった．初回検査で胃潰瘍や胃腺腫と診断された被検者から胃癌が発見される比率が高かった．内視鏡所見と性別，年齢で胃癌ハイリスク群を選定することは可能であり，ハイリスク群に対しては短期間で重点的な内視鏡検査を行う必要がある．

　Endoscopic mass screening for gastric cancer has begun in Japan, in addition to mass survey by x-ray examination. However, population endoscopic screening is thought not to be cost-effective, and so targeted screening strategies are required. A total of 3,672 participants were enrolled in our surveillance program and were repeatedly examined via gastric endoscopy with an interval of less than three years. Eighty one patients（2.2％ : 57 male and 24 female）developed gastric cancer after obtaining negative results. The interval from the initial examination to diagnosis as gastric cancer was less than 3 years in 24 patients, less than 6 years but more than three years in 26 patients, and more than 6 years in 31 patients. The incidence in males was higher than in females and was 3.9％ by the eighth year（p＜0.001）. The incidence in those more than 55 years old was significantly higher than that in those less than 54 years old, and was 4.4％ by the eighth year（p＜0.001）. The incidence in the participants with moderate or marked atrophy of the gastric mucosa was higher than that in those with slight or no atrophy, and was 8.1％ by the eighth year（p＜0.001）. Patients who developed gastric cancer were often diagnosed as having gastric adenoma or gastric ulcer during the initial endoscopy. Endoscopy could identify high-risk gastric cancer when two findings（gastric lesion, atrophy）, age, and male gender were combined. Endoscopic mass screening should be used to focus on these high-risk groups.