大腸腫瘍内視鏡的治療後の局所遺残再発―腺腫・m癌を中心に

A Study of Remnant or Recurrent Colorectal Lesions (Adenoma, Mucosal Carcinoma) after Endoscopic Resection

要旨　内視鏡的に切除された大腸腺腫2,720病変と粘膜内（m）癌264病変のうち，6か月以上経過が観察されていたものは腺腫1,387病変（経過観察率51.0％）とm癌193病変（経過観察率73.1％）の計1,580病変であった．このうち切除時の内視鏡所見から初回治療が肉眼的に不完全切除と判断される14病変を除いた1,566病変（腺腫1,382病変，m癌184病変）を対象として，内視鏡切除後の局所遺残再発について検討した．遺残再発は腺腫4病変（0.3％），m癌7病変（3.8％）の計11病変（0.7％）に認められた．遺残再発例の肉眼型は，Ⅰs2病変，Ⅱa3病変，結節集簇様病変6病変で，Ⅰp型と陥凹を伴う表面型腫瘍には遺残再発はみられなかった．遺残再発例は全大腸に分布していたが，遺残再発率は直腸と盲腸において高かった．また，大きさ別にみた遺残再発率は30mm以上と30mm未満の病変との間に有意差が認められた（25.0％vs0.3％；p＜0.001）．更に，初回治療が3分割以上と2分割以下の病変での遺残再発率にも有意差が認められた（20.8％vs0.4％；p＜0.001）．以上から，腺腫，m癌における内視鏡的切除の適応は，大きさ30mm程度までの病変で，それ以上の病変は相対的適応とすべきであり，3分割以上となった病変ではその後の注意深い経過観察が必要である．初回経過観察は，遺残再発確認までの期間からみて，治療後6か月から1年以内に行い，少なくとも3年間程度は毎年経過観察が必要と考えられた．

　We studied local remnant lesions or recurrent lesions in 1566 colorectal neoplasms (adenoma, mucosal carcinoma) on which was performed follow-up endoscopy at least once over six months after endoscopic resection. Local remnant or reccurence was recognized in eleven neoplasm (0.7%) of the total, The histological findings at the initial endoscopic treatment of these 11 lesions showed that four were adenoma and seven were mucosal carcinoma. The first morphological types of these lesions were Ⅰs (two cases), Ⅱa (three cases) and nodule-aggregating lesions (six cases). There were no cases of remnant or reccurent Ⅰp type or superficial depressed type. The incidence of the remnant or reccurent lesions was higher at the rectum and the ceacum. The initial size of tumors more than 30 mm in diameter had a higher incidence of remnant or reccurent lesions than these of under 30 mm (25.0% vs 3.2%; p ＜ 0.001), and cases of piecemeal resection more than three times also had a higher incidence than cases of two times or cases of enbloc resection at the initial treatment (20.8% vs 3.9%; p＜0.001).

　Considering these results, we concluded that endoscopic resection in the treatment of adenoma and mucosal carcinoma is generally indicated when the size of tumor is below 30 mm.

　Moreover, considering the period from the initial endoscopic treatment in our cases to the detection of their remnant lesions or reccurence, we recommend follow-up intervals in cases with high risk of remnant or reccurence. For example, the first follow-up colonoscopy should be performed six months or one year after treatment, and then every year at least up to three years after the initial endoscopic treatment.