A modified approach of port-access lymphadectomy for locally advanced non-small cell lung cancer: A single center experience

Abstract

Objective

Systematic nodal dissection (SND) is an important component of locally advanced non-small cell lung cancer (NSCLC), but modification of this procedure is rarely reported. In this paper, we reported a modified technique of systematic mediastinal lymph node dissection (MLND) of operable lung cancer by video-assisted thoracic surgery (VATS). Parallel upward dissection (the PUD technique) was named due to this modification and the efficacy of the PUD technique was evaluated as well.

Methods

We summarized the tips of the PUD technique and its version was updated in surgical aspect. The design and procedure sequence of the PUD technique were introduced in detail as well as its pros and cons. A retrospective study was performed on 998 cases of locally advanced NSCLC which accepted the PUD procedure in Department of Thoracic Surgery, Second Xiangya Hospital, Central South University, from 2012 to 2020. The perioperative mortality and the incidence of general and serious complications (such as recurrent laryngeal nerve injury, bronchopleural fistula) were analyzed.

Results

All the 998 cases were operated successfully with the PUD technique and few post-operation complications were found. There was no perioperative mortality and severe complication such as recurrent laryngeal nerve injury and bronchopleural fistula.

Conclusion

The PUD technique is safe and convenient and it can be a good supplement to the existing surgical techniques for locally advanced lung cancer.

The concept of systematic nodal dissection (SND) comes from the term of “radical lobectomy”, which was introduced by Cahan in 1960^[1]. The SND procedure has been accepted by the International Association for the Study of Lung Cancer (IASLC) as an important component of intrathoracic staging. Since video-assisted thoracic surgery (VATS) lobectomy with lymph node dissection was firstly reported in 1994^[2], this minimally surgical technique has been gradually and greatly improved^[3]. Compared with a traditional thoracotomy, VATS and robot-assisted VATS (R-VATS) have shown their superiority in recent two decade^[4-6]. The technique of SND by VATS, however, was rarely reported. A debate of “Why” always takes place before talking “How” because that there is no oncological benefit of SND by VATS for early-stage patients of non-small cell lung cancer (NSCLC)^[7]. Nevertheless, there is no argument that SND improves the staging of patients with NSCLC at the time of resection by appropriately upstaging patients without clinically obvious lymph node involvement and enabling the use of adjuvant therapy, which may improve survival^[8-11]. In this report, we describe a modified method of SND by VATS which called parallel upward dissection (PUD) to deal with the intraoperative mediastinal lymph node resection with primary lobectomy.

1. Materials and methods

1.1. Patient selection

The indication of SND with lobectomy includes II to III stage NSCLC patient according to the National Comprehensive Cancer Network (NCCN) guidelines. From 2012 to 2020, 998 patients with NSCLC [(61.4±13.8) years old] in the Department of Thoracic Surgery, Second Xiangya Hospital of Central South University were included in our program. The patients' general data were listed as Table 1.

Table 1.

Characteristics of patients in the PUD program

Characteristics	Patients/[No.(%)]
Sex
Male	501(50.2)
Female	497(49.8)
ASA score
1	245(24.5)
2	753(75.5)
pStage
IIa	240(24)
IIb	386(38.7)
IIIa	361(36.2)
IIIb	11(1.1)
Histology
Adenocacinoma	773(77.5)
Squamous carcinoma	156(15.6)
Other	69(6.9)

ASA: American Society of Anesthesiologists.

n=998

1.2. Surgical Technique

In our Department, video-assisted lobectomy was usually performed with 4 incisions (from 2012 to 2013) and was updated to 3 ports (from 2013 to 2014). Up to date, 2 ports or uni-portal operation was the routine (since 2014). The main incision lied in the 5^th intercostal space at the boarder of the pectoralis major muscle, 3-4 cm in length. The entire operation was conducted with the view on the monitor, without rib spreading. Combinations of minimally invasive and routine instruments were used. The harmonic scalpel played an important role in the procedure.

The PUD technique started from the bottom lymph node group (level 9, 8, 7) to hilar (level 10), then from hilar to the top group (level 6, 5, 4, 2) upwards. The resection line was parallel to the important structures around the lymph nodes such as esophagus, bronchial membranous, aorta, vagus nerve and was branches, trachea, and superior vena cava. The dissection is three-dimensional, from posteromedial to posterolateral (Figure 1). The organs were skeletonized and the lymph nodes were dissected as an integrated mass with the surrounding fatty tissues.

Figure 1. Sketch map of the PUD technique .

The resection movements are noted as the black arrows. R: Right side; L: Left side.

For the treatment of both sides, the first step was the transection of the inferior ligamentum pulmonale. On the right side, when the inferior lung vein was visible, resection could be parallel to the right bronchial membranous posterolateral and parallel to the esophagus posteromedial, and in upward direction to the subcarinal region. Then the level 9, 8, 7 lymph nodes were dissected entirely (Figure 2A). With the exposure of right upper bronchus after cleaning of the adjacent lymph nodes, the azygos vein was preserved and retracted upwards, harmonic scalpel went parallel to the trachea and right vagus nerve posteromedial and parallel to the superior vena cava anterolateral until it turned straight to the pleura apex. The level 4, 2 lymph nodes were dissected (Figure 2B). Usually a reflow vein from the SVC should be enclosed by a hemlock.

Figure 2. Vision of mediastinal lymph node dissection by the PUD technique .

A: Level 9, 8, 7 lymph node dissection, right-side; B: Level 2, 4 lymph node dissction, right-side; C: Level 9, 8, 7 lymph node dissection, left-side; D: Level 5, 6 lymph node dissection, left-side. The PUD resection lines are noted as the yellow arrows.

As to the left side, with proper exposure of posterior lung hilum, resection started parallel to the aorta from the inferior lung vein upward to the aortic isthmus. Resection line should posterolaterally be kept parallel to left bronchial membranous from the inferior lung vein upward to the subcarinal region, then the level 9, 8, 7 lymph nodes were dissected entirely (Figure 2C). Another resection line was from the anterior hilar upward to the aortic arch and parallel to the left phrenic nerve. After the level 10 lymph node dissection, resection line should still be kept parallel to the aortic arch and the left vagus nerve (Figure 3). After transection of the liganmentun Botalli, with resection upward to the lateral side of arch, the level 5, 6 were dissected (Figure 2D).

Figure 3. Vision after 4L lymph node cleaning.

2. Results

The PUD technique were successfully achieved in all patients’ surgery. Of 998 patients, few postoperation complications were found. There were 3 cases of post-operation hemorrhage, 9 chylothorax, 4 atelectasis, and 17 air leak over 3 days. There was no perioperative mortality and severe complication such as recurrent laryngeal nerve injury and bronchopleural fistula.

3. Discussion

At present, the oncological benefit for the systematic nodal dissection of early stage NSCLC patients could not be proven. The ACOSOG Z0030 study^[7] showed that there is no survival advantage between sampling and resection of lymph nodes for the early stage patients. Following this consensus, all early-stage patients in our department were not included in the PUD technique program. As systematic nodal dissection is the most precise method for lymph node staging, according to the NCCN guidelines, only the patients of locally advanced lung cancer in this program received the systematic nodal dissection by VATS with primary lobectomy.

The PUD technique is defined as a technique of systematic nodal dissection which contains 2 aspects. One is parallel, which means the resect movements should be parallel to the important anatomic organs and structures. The other is the upward direction of the resection.

One advantage of this technique lies in its convenience. Wherever on right side or left side, good exposure is the fundamental factor for the procedure. With better vision the operator can get more angulations for dissection.

The other advantage of this technique exists in its safety. The surgical risks of the locally advanced patients are quite different from early-stage ones. The anatomic spaces are not clear from the non-chemotherapy patients. In the employment of this modified technique, the resection line is parallel to the important structures around the lymph nodes. This measurement can greatly reduce the risk of structure injury. There were only 3 hemorrhage cases of injury in our program due to pulmonary blood vessel invasion by calcified lymph nodes. Few specific complications were found after VATS operation. The cough cases were recovered within 6 months after operation. This may be due to the tissue renewing which filled the cavity after the lymph node dissection. In our exploration, there are 9 chylothorax cases, 6 of which received VATS reoperation for ligation of the lymphatic duct near the azygos and vagus nerve right-sided. The incidence of complications in our department was not inferior to that of other centers^[12].

Still another advantage is its integrity, which means total removal of the lymph nodes and the fatty tissues at visible level in operation field. Under common circumstances, the camera port is located in the lowest position of chest wall. The upward visual angle is much more natural than in any other direction and the upward resection line can greatly reduce the randomness of the dissection such as the “spot to spot” technique. The modification of this technique is based on routine lymphadectomy ones such as Khalid’s technique^[13]. After induction chemotherapy, some patients’ lymph nodes might be integrated with surrounding tissue. By using parallel resection line and in the upward direction, expectation of total removal at visible level in operation field is available and no groups might be neglected. As for frozen cases, VATS approach is not suitable in general^[14].

The station 4L is in very deep location, which indicates small operative space in dissection. Exposure of this area is difficult and we prefer soft retraction needed for preventing fatal bleeding and nerve injury^[15]. The bipolar and hemo-lock are used in this region so as to reduce the probability of the injury of recurrent laryngeal nerve.

Based on our 10-year-experience, the PUD technique is safe and convenient and it can be a good supplement to the existing surgical techniques for locally advanced lung cancer.

Funding Statement

This work was supported by the National Natural Science Foundation (82170095) and the Changsha Municipal Natural Science Foundation (kq2014228), China.

Conflict of Interest

The authors declare that they have no conflicts of interest to disclose.

Note

http://xbyxb.csu.edu.cn/xbwk/fileup/PDF/2021111227.pdf