食道SM癌の治療選択—内視鏡治療の立場から：JCOG0508のデータを踏まえて

Treatment Options for Esophageal Submucosal Cancer from the Perspective of Endoscopic Treatment, Based on The Data of JCOG0508

要旨●食道SM癌は20〜40%でリンパ節転移があり，外科的切除および化学放射線療法（CRT）が推奨される．しかし，腫瘍が比較的浅い場合の深達度診断や，脈管侵襲の有無などを臨床的に正確に診断することは困難である．術前にSM癌と診断されて食道切除やCRTを受けることは，結果的に粘膜内癌症例である場合は過大な治療となる可能性もあることから，内視鏡治療を先行させ，深達度や脈管侵襲を評価し，リンパ節転移リスクが高い対象に対してのみ追加治療を行うストラテジーが考えられた．JCOG0508試験では，診断的内視鏡的切除と追加CRTの有効性が示された．今後は，追加CRTを行った症例における再発のリスク評価や，画像強調内視鏡を併用した術前診断の精度向上に基づく治療の振り分けが進められるべきである．

　Esophageal submucosal cancer has a rate of lymph node metastasis percentage of 20%-40% ; therefore, surgical resection and chemoradiotherapy are recommended. However, it is difficult to clinically diagnose the depth of invasion, especially when the tumor is relatively shallow, and to accurately detect the presence or absence of lymphovascular invasion. Clinical submucosal cancer has sometimes been diagnosed as pathological mucosal cancer, and in such cases, a more aggressive approach, such as surgery or CRT（chemoradiotherapy）, is undertaken. We considered a strategy in which endoscopic treatment is preceded by an evaluation of the tumor depth and lymphovascular invasion, where additional treatment is only administered to subjects with a high risk of lymph node metastasis. JCOG0508 showed the efficacy of diagnostic endoscopic resection followed by preventive CRT. In the future, a risk assessment of recurrence in such cases should be performed before using additional CRT, and the idea of deciding on the treatment strategy based on the improvement in the accuracy of preoperative diagnosis using image-enhanced endoscopy should be promoted.