[Development of Virtual-assisted Lung Mapping]

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 (VALMAP), 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 chal-lenges. 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.