大腸腫瘍内視鏡的粘膜切除標本による局所根治度判定―実体顕微鏡を併用して

Local Recurrence of Colorectal Tumors after Endoscopic Mucosal Resection: Evaluation of the Lateral Margin of Resected Specimen by Stereomicroscopy

要旨　EMR直後に内視鏡的には遺残なしと判定され，6か月以上経過観察された大腸粘膜内腫瘍性病変233病変（腺腫137病変，癌96病変）を対象として，組織学的所見と実体顕微鏡所見により摘除標本側面断端の腫瘍組織の有無別に局所再発率を比較し，更に大きさとの関係についても検討した．側面断端陰性（A-margin）では局所再発は認めず（0/180），側面断端陽性（P-margin）の9.4％（5/53）に局所再発を認めた．したがって，EMR直後，内視鏡的に遺残を認めなくても側面断端に組織学的，実体顕微鏡的に腫瘍組織の存在する病変は局所再発の可能性があり，慎重な経過観察が必要である．また，完全摘除の期待できる大きさは20mmまでであると考えられた．

　We evaluated intramucosal local recurrences of 233 colorectal tumors which were removed by endoscopic mucosal resection (EMR). All of these resections were judged as successful because of endoscopic absence of residual tumor immediately after EMR. The presence of residual tumor was determined by histologic and stereomicroscopic examinations of the lateral margins of resected specimens. There was no evidence of intramucosal local recurrence in 180 lesions with negative margins. However, intramucosal local recurrence occurred in 5 of 53 lesions (9.4%) with positive margins. Tumors removed by EMR that appear margin negative by endoscopy, but are found to be margin positive by histology and/or stereomicroscopy, may recur locally. Therefore, careful follow-up by endoscopy is required.

　The present study also examined the relationship between tumor size and status of the lateral margins of specimens resected by EMR. These findings suggest that the size limit for complete resection by EMR is 20 mm.