術前気管支鏡下肺マッピング法の新たな展開

Development of Virtual-assisted Lung Mapping

1995年，米国Lung Cancer Study Groupによる前向きランダム化比較試験で，縮小手術（肺部分切除，区域切除）は肺葉切除と比べて局所再発および長期生存が劣ることが報告された1）．これに基づき，長らく肺癌の標準術式は肺葉切除とされてきたが，2022年に本邦から日本臨床腫瘍研究グループ（JCOG）0802/西日本がん研究機構（WJOG）4607Lの結果が公表され，病変全体の径2.0 cm以下かつ充実成分優位（C/T比0.5以上）の非小細胞肺癌において，区域切除の全生存期間が肺葉切除のそれを有意に上回ることが明らかとなった2）．この結果をふまえ，今後は小型肺癌における肺癌縮小手術の適応と重要性はさらに増してくることが予想されるが，肺癌縮小手術にはいくつかの問題点が存在する．第一に，小型病変が多いため，特に胸腔鏡下手術やロボット支援下手術などの低侵襲手術においては，術中に腫瘍部位を同定することが困難である場合が少なくないことである3，4）．第二に，術後局所再発や患者生存に影響を及ぼしうる切除マージン（腫瘍径以上または2 cm以上の切除マージンが理想とされる）が確保できないことがある5）．JCOG0802/WJOG4607L試験でも，区域切除群で肺葉切除群よりも局所再発率が有意に高い結果であった．第三に，解剖学的に規定された肺葉切除とは異なり，縮小手術（特に部分切除）では切除範囲が主観的になりやすく，再現性に乏しいことがあげられる．

The Japan Clinical Oncology Group （JCOG） 0802/West Japan Oncology Group （WJOG） 4607L trial has recently reported that in small lung cancer, segmentectomy has a higher overall survival rate than lobectomy, increasing the significance of sublobar resection. However, local recurrence is a major concern after sublobar resection, and an insufficient surgical margin is a significant risk factor for locoregional recurrence. Therefore, since 2014, we have performed virtual-assisted lung mapping （VAL-MAP）, a preoperative bronchoscopic multiple-spot dye-marking technique, using indigo carmine as a preoperative localization technique to identify hardly detectable pulmonary nodules and confirm the adequacy of the surgical margin. However, conventional VAL-MAP （VAL-MAP 1.0） faced some challenges. One issue is that approximately 10％ marks were invisible and unidentifiable due to patient factors or technical issues. Another problem was that, in some cases requiring large resection depth, VAL-MAP did not lead to successful resection with adequate surgical margin. Thus, we have invented several novel techniques to solve these issues. VAL-MAP dual staining is a technique using indocyanine green （ICG） as well as indigo carmine that has improved the success rate of marking detection during surgery without causing additional complications. VAL-MAP 2.0 is a proximal mapping technique that involves the use of a coil, enabling three-dimensional mapping and making sublobar resection more accurate, particularly for a deeply located tumor.