10mm以下の大腸sm massive癌の超音波内視鏡診断

Diagnosis of Colorectal Cancer by Microscanner (MS) Evaluation of Submucosal Cancer (sm Massive Cancer) That is 10 mm or Less in Size

要旨　大腸sm massive癌97例を腫瘍径10mm以下のA群(19例)とそれより大きいB群(78例)に分け，細径超音波プローブ(MS)の病変描出能と深達度診断能を検討した．描出能と深達度正診能はA群でいずれも100％であったが，B群では77％，78％と低かった(p＜0.05)．A群では腫瘍高が低く，至適距離による詳細な走査ができること，粘膜下層の線維化や炎症細胞浸潤などの組織学的所見に乏しいことが，良好な描出能，深達度正診能の原因と考えられた．したがって，10mm以下の病変の深達度診断にMSを積極的に用いることにより，適切な内視鏡的粘膜切除術の適応決定が可能になると考えられる．

　We evaluated the detection rate and diagnostic accuracy of the depth of invasion of ultrasonographic examination using a microscanner (MS) in patients with colorectal cancer that had invaded deeply into the submucosa (sm massive cancer). Ninety-seven patients with histologically proven sm massive cancer, who underwent both preoperative MS and surgery, were divided into two groups based on size: group A (19 patients) was defined as cancer 10 mm or less in size, and group B (78 patients) as cancer greater than 10 mm. The detection rate and diagnostic accuracy of the depth of cancer invasion in group B were 77％ and 78％, respectively, lower than those in group A (100％ and 100％) (p＜0.05). The reasons for the better results in group A were presumed to be that 1) the height of lesions in group A was lower than that in group B, 2) scanning of the entire lesion was able to be performed in group A much better than in group B, and 3) the lesions in group A were accompanied by less fibrosis or inflammatory cell infiltration than those in group B.

　We conclude that MS should be indicated for patients with cancerous lesions 10 mm or less in size to determine appropriate candidates for endoscopic mucosal resection.