The present study shows that the surgical outcomes of VATS CL and thoracotomy CL were not significantly different. Generally, the VATS approach is superior to thoracotomy in terms of magnifying the operative field, knowledge of the surgical technique, reduction of postoperative pain, and faster recovery of postoperative pulmonary function [11]. Nevertheless, VATS CL long after segmentectomy in the same lobe has not been reported because it is extremely difficult due to severe hilar adhesions. In Japan, radical and anatomical pulmonary segmentectomies are actively performed in cases involving early lung cancers with peripherally located small-sized tumors. A prospective study reported no recurrence of primary lung cancer during a 5-year follow-up period after limited resection of lung cancer with a maximum tumor diameter of 8–20 mm, a ground glass opacity (GGO) ratio > 80% on computed tomography, and clinical T1N0M0 classification. Moreover, the 5-year disease-specific and overall survival rates were 100 and 98%, respectively [6].
At our institute, radical and anatomical pulmonary segmentectomies are performed in cases involving lung cancer with peripheral pulmonary nodules < 20 mm in diameter and a GGO ratio > 50% on computed tomography. Preservation of lung function after segmentectomy results in a large amount of resectable metachronous second primary lung cancer in the non-resected lobe after segmentectomy of the initial primary lung cancer [8, 9]. On the other hand, the detection of new solitary pulmonary nodules during postsurgical follow-up in the previously resected lobe, especially after limited resection, poses a diagnostic challenge. At our institute, intraoperative frozen-section diagnosis is performed to decide which surgical treatment is needed for lesions, without preoperative pathological diagnosis, suspected to be recurrent and/or second primary lung cancer after lung cancer segmentectomy. Nevertheless, CL is necessary when intraoperative frozen section diagnosis indicates malignancy during surgeries for lesions suspected of local recurrence and/or second primary lung cancer. CL is one of the treatments for patients with local recurrence and/or a second primary lung cancer and/or metastasis after lung cancer segmentectomy. In our study, CL was performed in four cases with suspected local recurrence, in four cases with a suspicion of a metachronous second primary lung cancer, and in two cases with metachronous metastasis from non-lung primary malignancy in the same lobe as the one previously resected (Table 1).
CL long after segmentectomy is difficult because mobilization of the hilum structure is challenging owing to dense adhesions around it that have already been divided and manipulated during the previous segmentectomy. In fact, it was reported that CL may become more difficult to perform approximately 5 weeks after segmentectomy [10]. In our study, CLs were performed at least a month after the previous lung cancer segmentectomies, and hilum adhesion was especially severe after superior mediastinal ND during the previous lung cancer segmentectomies (Tables 2 and 3).
Taping and/or clamping of the main pulmonary artery is occasionally needed to prevent catastrophic bleeding when it is difficult to expose and divide the pulmonary artery because of hilum adhesion. At our institute, we expose the pulmonary artery enough to clamp with forceps for the cases with severe hilum adhesion, and taping is performed in the case that pulmonary artery is completely isolated. It is more difficult to secure the pulmonary artery and/or arrest bleeding during the VATS approach than during the thoracotomy approach when bleeding occurs from the pulmonary artery. We think that VATS CL is safe to perform if each central main pulmonary artery is secured by the VATS approach. At our institute, pulmonary artery occlusion using silk suture (double looping technique: DLT) has been performed for securing them during the VATS approach [12]. From this point of view, we consider that our exclusion criteria for VATS CL, which may cause difficulty in using DLT, are appropriate. Opening of the pericardium and intrapericardial main pulmonary artery taping, which are needed to address severe hilum adhesion around the superior vena cava and main pulmonary artery in right CL, are difficult to perform safely with the VATS approach. On the other hand, it is also difficult to isolate the main pulmonary artery in patients with adhesion around the ligamentum Botalli, which often needed to be cut before the main pulmonary artery can be isolated. Nevertheless, the length of the left central pulmonary artery is longer than the right. In this study, two of the 10 patients who underwent CL received pulmonary artery taping. One patient underwent main pulmonary artery taping with a silk suture during VATS CL, and the other underwent intrapericardial pulmonary artery taping during the thoracotomy CL (Tables 2 and 3). The patient with pulmonary artery injury underwent pulmonary artery occlusion with a silk suture, and the suturing was performed via the VATS approach, without conversion to thoracotomy.
We suggest that VATS CL long after segmentectomy for lung cancer can be performed without fatal complications; however, we experienced a case wherein VATS was converted to thoracotomy for a left upper CL to arrest bleeding from the main pulmonary artery (Table 3). In this patient, exposing and securing the main pulmonary artery was technically difficult during the VATS approach because of severe adhesion around the main pulmonary artery and aorta, though it was possible to arrest the bleeding by using the VATS approach.
There are several limitations associated with this study. First, the study included very few patients; therefore, the lobes that underwent previous segmentectomy and the regions in which ND was carried out were inconsistent during VATS and thoracotomy CL. However, we conclude that because of severe hilum adhesions, CL may become more difficult after radical superior mediastinal ND. Second, the present study had a retrospective design. Although it may be difficult to conduct a large-scale and prospective study of CL, many reports of CL will be necessary to acquire robust evidence to support the safety of VATS CL.