大腸腫瘍の自然史―大腸癌研究会の報告からの検討

Growth Pattern of Colorectal Tumours: From the 44th Meeting of the Japanese Research Society for Cancer of the Colon and Rectum

要旨　経時的変化が捉えられた大腸腫瘍として，第44回大腸癌研究会に報告された症例の集計から，大腸腫瘍の自然史について考察した．2型ないし3型進行癌の初期病変としては，表面隆起型（Ⅱa，Ⅱa＋Ⅱc）ないし無茎性病変（Ⅰs）が全体の2/3を占めていた．また，表面隆起型が隆起型へ形態変化することはまれではないことが明らかとなった．しかし，表面陥凹型（Ⅱc，Ⅱc＋Ⅱa）の自然史については報告例が少なく，十分な検討はできなかった．大腸腫瘍の自然史の解明のためには，内視鏡による表面陥凹型病変の発見と，prospectiveな経過観察が必要であろう．

　Morphological changes were analyzed chronologically in 98 colorectal tumours presented at the 44th Meeting of the Japanese Research Society for Cancer of the Colon and Rectum. Retrospective study showed that types Ⅱa and Ⅰs were the predominant initial shapes of Type 2 or 3 advanced cancer. In this study, type Ⅱa to type Ⅰs and type Ⅱa to Type 1 transitions were not infrequently observed. Prospective investigation of 24 superficial type tumours revealed that type Ⅱa to type Ⅰs and type Ⅱa ＋ Ⅱc to type Ⅱa transitions actually existed. However, natural history of type IIc and Ⅱc ＋ Ⅱa tumours is not unveiled yet. More effort is needed to find type Ⅱc and Ⅱc ＋ Ⅱa lesions and follow them prospectively to clarify their natural history.