胃EMRの適応拡大：大きさからみて―組織学的検索の重要性と一括切除の必要性：ITナイフを含めた検討

The Importance of Histological Evaluation and the Necessity of One-piece Resection for Endoscopic Gastric Mucosal Resection

要旨　国立がんセンター中央病院では，1987年より2001年までに，1，101病変に対するEMRが施行されている．治療前にガイドラインの条件を満たしEMRが施行された772病変のうち治癒切除は579例（75％），非治癒切除は110例，組織学的評価不能は83例であった．当センターの適応拡大基準を満たした329病変における治癒切除は214例（65％），非治癒切除，評価不能は78例，37例であった．一括切除された799病変のうち，治癒切除647例（81％）では遺残再発は認めず，評価不能は35例（4％）であった．分割切除では，治癒切除例においても5例（3％）の遺残再発を認め，評価不能は85例（28％）であった．最近のITナイフを用いたEMRでは，96％（372/388）が一括切除され，評価不能は2例（0.5％）のみであった．正診率に限界がある以上，切除後の正確な組織学的検索は必須であり，そのためには病変は一括で切除されるべきである．

　It is well known that EMR allows us to perform less invasive but curative treatment. At the National Cancer Center Hospital, endoscopic mucosal resection (EMR) is applied in patients with early gastric cancers up to 30 mm in size that are well or moderately differentiated in type regardless of ulceration or more than 30 mm if there is no ulceration, but definite signs of submucosal invasion. This means that the patients with such cancers have a low risk of lymph-node metastasis.

　From 1987 to 2001, 1,101 lesions were treated by EMR. The curative resection rate was 72% (793/1,101). One hundred and twenty lesions (11%) were classified into a not-evaluable group. Among the tumors resected in one piece, 81% (647/799) were curative, resections, and 4% were in the not-evaluable group. When the tumors were removed by multiple fragments, 146 tumors (48%) were histologically confirmed as curative resections, but 5 local recurrences (3%) developed in the fragmented curative resections compared with no residual cancers in the one-piece curative group. The insulation-tipped electrosurgical knife (IT knife) is providing excellent therapeutic resects. In the last 2 years, 96% of the tumors (372/388) were resected in one piece using this procedure.

　The endoscopic distinction between mucosal and submucosal invasion is made correctly in only approximately 80% of cases, which means that the pretreatment diagnosis would be incorrect for 20% of the tumors that are candidates for EMR. Accurate histological examination of the specimen resected by EMR is essential for correct surveillance. One piece resection makes possible a correct recommendation for patients with early gastric cancer.