表面型表層拡大型食道癌の深達度診断―内視鏡の立場から

Endoscopic Diagnosis of Invasion Depth for Superficial Spreading-Type Esophagus Cancer

要旨　当院における表面型表層拡大型食道癌の深達度診断精度は75.6％であった．内視鏡によりT1a-EP/LPM癌と診断した場合の深達度診断精度を大きさ別に検討したところ，25mm未満が94.0％，25mm以上，50mm未満が86.8％，50mm以上が71.9％と，病変が大きくなるほど低下した（p<0.001）．誤診例の多くは，実際の深達度より内視鏡で浅く診断した，いわゆる浅読み症例であった．誤診例9病変のうち4病変は表層とは非連続的な成分で深部浸潤しており，その診断は困難と考えられた．他の5病変は1mm程度の小さな範囲で浸潤しているものであった．今後診断精度を向上させるには，1mmレベルの微小浸潤を同定し，診断しなければならない．

　In this study, we analyzed data of patients with superficial spreading-type esophageal cancer who were treated between 2004 and 2011. Diagnostic accuracy for cancer invasion depth was 75.6％. Diagnostic accuracy for lesions endoscopically diagnosed as T1a-EP/LPM cancer was also analyzed with regard to the lesions' size. The accuracy for lesions ～24mm, 25mm～49mm, and 50mm～ in size was 94.0％, 86.8％, and 71.9％, respectively（p<0.001）. The accuracy decreased with the increase in the lesions' size. Histological examination revealed that nine lesions were invading deeper than endoscopic diagnosis. Of nine lesions, four were invading into the muscularis mucosa or deeper besides invasion of the surface component, whereas the remaining five were invading into the muscularis mucosa or deeper by approximately 1mm width. To further improve diagnostic accuracy, diagnosis of such small invasions, which is considered a challenge, is required.