内視鏡完全一括切除可能な大腸T1癌の術前診断—注腸造影の有用性と限界

Profile Views of Early Colorectal Cancers during Barium Enema

要旨●過去10年間に注腸X線造影検査（BE）が施行された大腸T1癌133例を対象とし，BEの側面変形と粘膜下層（SM）浸潤距離の関係とSM 1,800μm以深癌の検出能を検討した．X線造影所見として二重造影像における病変部位の変形に着目し，管腔に対して水平方向および垂直方向の変形長を計測した．その結果，水平変形長（相関係数r＝0.6657，p<0.01），垂直変形長（r＝0.5197，p<0.01）ともにSM浸潤距離と正の相関を示した．SM 1,800μm以深癌の検出におけるカットオフ値は水平変形長4.5mm，垂直変形長0.5mmで，正診率はそれぞれ82.0%，79.7%であった．以上のカットオフ値に従って変形を陽・陰性に分けると，水平変形陽性例で陰性例よりもリンパ管侵襲，静脈侵襲の割合が高かった．以上より，水平変形長は脈管侵襲の予測因子であり，4.5mmまでの変形は内視鏡治療選択の指標となる可能性が示唆された．

　Objective：This study aimed to evaluate the association between profile views during BE（barium enema）and depth of SM（submucosal）invasion in early CRC（colorectal cancer）in T1 stage.

　Methods：We retrospectively enrolled patients with endoscopically or surgically resected CRCs with SM invasion, evaluated using BE in the past 10 years. We measured the horizontal and vertical widths of the deformity under profile view of BE at the site of the CRC and calculated the most appropriate cutoff values for discriminating SM invasion depth of ≥1,800μm from that of <1,800μm.

　Results：In 133 T1 CRCs, the horizontal deformity width（r＝0.6657, p<0.01）and vertical deformity width（r＝0.5197, p<0.01）showed moderate correlations with the depth of SM invasion. In order to predict the SM invasion depth of >1,800μm, the most appropriate cutoff value of the horizontal deformity width was 4.5mm with an accuracy of 82.0%, whereas that of the vertical deformity width was 0.5mm with an accuracy of 79.7%. Lymphovascular invasion was more common in CRCs with a horizontal width deformity of >4.5mm than in those with a deformity of <4.5mm（p<0.05）.

　Conclusions：The horizontal and vertical widths of the deformity on profile view during BE may be useful for predicting the SM invasion depth.