食道表在癌の疫学と危険因子

Etiology and Risk Factors of Superficial Esophageal Cancer

要旨　食道癌の疫学は，地域，人種，食生活などの生活習慣，喫煙や飲酒などの嗜好と深く関連している．本邦における食道癌の動態は，死亡率は男性においては横ばい，女性においては減少傾向にある．罹患率は男性では軽度増加傾向，女性は減少傾向にある．本邦における現状は，性別では男性に多く，年齢は60～70歳代が多い．占居部位は胸部中部食道に最も多く，組織型は扁平上皮癌が圧倒的に多い．また，同時性および異時性の他臓器重複癌が多いことが知られている．食道扁平上皮癌の危険因子としては喫煙や飲酒があり，頭頸部癌や食道アカラシア，腐食性食道炎患者も高危険群となる．腺癌の危険因子としては食道胃逆流症（GERD）に伴う下部食道の持続性慢性炎症に起因したBarrett上皮が知られている．これらハイリスク群に対する内視鏡検査によるスクリーニングが必要である．

　Development of esophageal cancer is regarded as being related to the area, the race, dietary habits, smoking and drinking.

　The mortality rate because of esophageal cancer in Japan is keeping its level in men, but decreasing in women. The morbidity is slightly increasing in men, but shows a decreasing tendency in women.

　Esophageal cancer in Japan occurs predominantly amongst males and is most frequently encountered in the 60 to 70 year age group. The most frequent location of the lesion is the middle thoracic esophagus and diagnosed mostly as squamous cell carcinoma.

　It is also well-known to often involve double cancer synchronously or metachronously.

　The risk factors of esophageal squamous cell carcinoma include smoking and alcohol, as well as head and neck cancer, esophageal achalasia, and cottosive esophagitis.

　The risk factors of esophageal adenocarcinoma include Barrett's epithelium caused by chronic continuous inflammation in the lower esophagus caused by gastro esophageal reflux disease.

　Endoscopical screening in these high risk groups is recommended.