超音波内視鏡を用いた大腸SM癌に対する深達度診断および内視鏡治療適応拡大の可能性

Invasion Depth Diagnosis with HFUP and Feasibility of Indication Extension of Endoscopic Resection for Colorectal Submucosal Carcinomas

要旨　2004年10月から2010年12月までに当科で超音波細径プローブ（high-frequency ultrasound probe ; HFUP）を用いて早期大腸癌274病変に対して深達度診断を行った．全体では，深達度正診率はM～SM-s癌では72.5％，SM-m癌では87.8％であり，隆起型，表面型いずれの肉眼型においてもSM-m癌の正診率がM～SM-s癌に比較して有意に高率であった．同時期に内視鏡治療を施行し，組織学的にSM浸潤距離測定が可能であった大腸SM癌64病変において内視鏡治療によるSM切除距離は平均3,900±2,200μmであった．また内視鏡治療の結果，深部断端陽性となった11病変におけるSM浸潤距離は平均4,200±2,100μmであり，内視鏡的に深部断端陰性として完全切除可能なSM浸潤距離はおよそ4,000μmと考えられた．また，HFUPを用いることで，術前にSM距離の計測が可能であり，HFUP上で計測したSM浸潤距離は組織学的SM浸潤距離と有意な相関を認めた（相関係数R＝0.889，p＜0.0001）．SM垂直浸潤距離1,000μmにおける診断能はHFUPで正診率95％と内視鏡検査の正診率85％，注腸X線検査の83％に比較して有意に高率であった（p＜0.05）．同様に，SM垂直浸潤距離4,000μmにおける診断能はHFUPで正診率85％と内視鏡検査の正診率45％，注腸X線検査の48％に比較して有意に高率であった（p＜0.0001）．以上から，今後の大腸SM癌の内視鏡治療の適応拡大に向けてHFUPは必須の検査法であることが示唆された．

　Between 2004.10 to 2010.12, HFUP was performed for 274 lesions of early colorectal carcinomas. Overall accuracy of invasion depth diagnosis was 72.5％, for M-SMs carcinomas and 87.8％ for SM-m ones. Accuracy rate was significantly higher in SM-m carcinomas than M-SM-s ones in both polypoid and, Flat and depressed type carcinomas. During the same period, 64 lesions SM carcinomas were endoscopically resected and SM invasion distance was able to be measured and the average resected SM layer distance was 3,900±2,200μm. Of those, pathological vertical cut end was positive in 11 lesions and the average resected SM distance was 4,200±2,100μm. It was strongly suggested that possible resectable SM distance by endoscopy with negative vertical cut end was about 4,000μm. Using HFUP, SM invasion distance was able to be preoperatively measured and SM invasion distance on HFUP image was favorably correlated with those on histological specimens（correlation coefficient R＝0.889, p＜0.0001）. Diagnostic accuracy for SM invasion distance 1,000μm was 95％, 85％ and 83％ by HFUP, conventional colonoscopy and barium enema study, respectively and it was significantly higher in HFUP than other modalities（p＜0.05）. Moreover, diagnostic accuracy for SM invasion distance 4,000μm that was endoscopically resectable SM invasion distance with negative cut end was 85％, 45％ and 48％ by HFUP, conventional colonoscopy and barium enema study, respectively and it was significantly higher in HFUP than in other modalities（p＜0.0001）. It is strongly suggested that HFUP will be the essential modality for the indication extension of endoscopic resection for submucosal carcinomas.