異時性多発大腸癌の検討―サーベイランスの指標を求めて

Clinical Study of Metachronous Multiple Primary Carcinomas of the Large Bowel

要旨　過去38年間に当センターで内視鏡的治療例，外科的治療例および非切除例の大腸癌（腺癌）3,149例3,542病変について異時性多発大腸癌を検討した．異時性多発大腸癌は2.4％に認め，平均年齢は62.1歳，男女比は1.88：1であった．進行癌＋早期癌の組み合わせが最も多くみられた．占拠部位は，第1癌の口側に発現する傾向があり，特に右半結腸に多くみられた．発現間隔は，平均6年で1～26年の長きにわたっていた．発現期間の分布をみると，3年未満の比較的早期と5年以上の2峰性を示していた．3年未満のものは見逃しの可能性を否定できず，3年以上のものを異時性と定義することを提案したい．また，術後の経過検査は必要であるが，5年以上経過しても全大腸，特に右半結腸に重点を置いた定期的な検査が必要である．

　For 38 years from 1961 to 1998, 75 cases with metachronous multiple primary carcinomas of the large bowel were diagnosed, polypectomized or/and operated on at our center. The 75 cases of metachronous multiple primary carcinomas accounted for 2.4% out of a total of 3,149 cases (3,542 lesions). The mean age was 62.1 years. Forty nine patients were men, and 26 were women, a ratio of 1.88 to 1. The metachronous multiple primary carcinomas were mostly found in cases where there was a combination of advanced cancer and early cancer. Compared with the incidence of single carcinomas, metachronous carcinomas were most likely to be located in the right colon. The average interval between the first and second carcinomas was six years ranging from one year to as long as 26 years. The distribution of the occurrence period showed two peaks: three years or less (at a relatively early stage) and longer than five years. Periodical colonoscopy should be undertaken one year after operation and polypectomy and even up to five years after the original treatment.