sm massive以深に浸潤した10mm以下の大腸癌の超音波内視鏡診断

Diagnosis of Endoscopic Ultrasonography for Colorectal Cancer, the Depth of Invasion of Cancers 10 mm in Diameter and Infiltrating Deeper than the Massive Mucosa

要旨　EUSを施行した大腸癌について深達度診断におけるEUSの役割を検討し，sm massive以深に浸潤した10mm以下の大腸癌におけるEUSの役割について考察した．(1)EUSによる描出不良率と描出不良例を含めた深達度誤診率はそれぞれ全体268病変で10.1％，16.8％，早期癌167病変で14.4％，25.1％であった．(2)描出不良率や深達度誤診率は腫瘍径別，深達度別(m，sm₁，sm_{2, 3}以深)，肉眼型別(0-Ⅰ型，0-Ⅱ型)いずれにも統計学的有意差は認めなかった．(3)10mm以下のsm massive以深癌12例中3例にEUS誤診例がみられた．しかし通常内視鏡検査で“迷って”診断した2例ではEUSにて確診された．そして結果的には通常内視鏡とEUSによる診断で1例を除いて，他は適切に処置された．以上の成績に考察を加え，10mm以下のsm massive以深癌であってもその深達度診断にはEUSは通常内視鏡との総合診断が必要であると結論した．

　We investigated the role of endoscopic ultrasonography for colorectal cancer, evaluating its ability to diagnose the depth of invasion of cancers 10 mm in diameter and infiltrating deeper than the massive mucosa.

　1) In a total of 268 lesions, the rate of inability to provide a sufficiently detailed result was 10.1％ and the rate of misdiagnosis of the depth of invasion was 16.8％. Furthermore, in 167 cases of early colorectal cancer, the rates were increased to 14.4％ and 25.1％ respectively.

　2) There was no statistically dominant relationship between the rate of insufficiently detailed or misdiagnostic study, and size, depth of invasion in the early stage and macroscopic shape.

　3) Three misdiagnostic cases were found in 12 cases of small (within 10 mm) sized colorectal cancers which had infiltrated deeper than the massive submucosal layer. However, two of these 12 cases had been diagnosed accurately by endoscopic ultrasonography, but could not be diagnosed by ordinary endoscopic study. As a result, proper clinical treatment was performed except in one case. Considering these results, we conclude that, for the accurate detection of the depth of invasion, it is necessary to make a synthetic assessment using a combination of endoscopic ultrasonography and ordinary endoscopy for diagnosis of colorectal cancer, even for those lesions within 10 mm in size.