大腸癌のEUS診断

Diagnosis of Colorectal Cancer Using Endoscopic Ultrasonography

要旨●大腸癌の内視鏡診断に際してEUSは，深達度を客観的に評価できる利点を有する．特に早期大腸癌に対しては，内視鏡的摘除の適応判定などに活用できる．EUS診断を行った早期大腸癌866病変の検討では，治療法の選択という面での正診率は90%と良好であった．また，潰瘍性大腸炎関連腫瘍に対するEUSの診断成績も良好であった．EUS診断は，描出困難病変が多いなどの問題点があるが，大腸腫瘍に対するESDの普及もあって大腸pT1b癌に対する内視鏡治療の適応拡大が議論されており，EUSの意義が再評価されている．なお，大腸癌に対してEUSがその能力を十分発揮するためには，大腸用のEUS機種の改良が必要である．

　EUS（endoscopic ultrasonography）objectively evaluates the depth of invasion during the endoscopic diagnosis of colorectal cancer. It is particularly useful in determining the feasibility of endoscopic resection for the treatment of patients with early colorectal cancer. In a study involving 866 early colorectal cancer lesions diagnosed using EUS, the rate of correct diagnosis with respect to the selection of the most appropriate treatment method was satisfactory（90%）. In addition, EUS demonstrated good results for the diagnosis of tumors associated with ulcerative colitis. EUS is also characterized by limitations such as frequent difficulties in imaging lesions. However, the extension of the range of indications for this method to include the endoscopic treatment of pT1b colorectal cancer is being discussed, in association with the increased use of ESD（endoscopic submucosal dissection）for the treatment of colorectal tumors. The clinical significance of ESD is currently being reevaluated. Realizing the complete potential of EUS for the management of colorectal cancer may require the development of improved instruments for performing EUS for colorectal cancer.