With the continuous development and maturation of the concept of minimally invasive surgery, minimally invasive surgery for lung cancer has made great progress in the past 20 years. Currently, video-assisted thoracoscopic surgery (VATS) is the main procedure for minimally invasive lung cancer surgery. Although the feasibility, safety and thoroughness of tumor resection of minimally invasive thoracoscopic lung cancer surgery had aroused controversies, with the publication of the results of multicenter studies at home and abroad, VATS can achieve the same effect as traditional open-heart surgery in lung cancer treatment.
However, the current minimally invasive treatment of lung cancer still remains in the minimally invasive surgical pathway, and how to transition to preserving more lung tissues so as to achieve a comprehensive and substantial minimally invasive treatment is worth further exploration.
1. History of minimally invasive surgical treatment of lung cancer
Since Graham first successfully used anatomical total lung resection for lung cancer surgery in 1933, surgical procedures for lung cancer have been systematically explored. Currently, lobectomy combined with mediastinal lymph node dissection using the postero-lateral approach has become the standard surgical treatment for lung cancer.
However, its disadvantages include long surgical incision, huge trauma, necessity to cut off the latissimus dorsi and anterior serratus muscles, more bleeding, long switching chest time, slow postoperative recovery, especially severe postoperative pain, which may lead to cardiovascular and respiratory system complications. In addition, the standard posterior lateral incision destroys the structure of the shoulder girdle muscles, which easily leads to persistent postoperative chest pain and frozen shoulder, and decreases the quality of life of patients after surgery.
In the late 1980s, the minimally invasive thoracotomy (MST), which preserves the integrity of the latissimus dorsi muscle and does not destroy the structure of the shoulder girdle muscle, was introduced, and postoperative pain and shoulder dysfunction were significantly reduced. With the emergence of new surgical equipment and instruments and the continuous improvement of lumpectomy technology, Lewis first reported the lobectomy procedure of lung cancer treated by televised thoracoscopy in 1992.
2.Minimally invasive surgical techniques for lung cancer
It mainly includes two categories: small incision surgery with preservation of chest wall muscles and thoracoscopic surgery.
2.1 Lung cancer surgery with preservation of chest wall muscles (muscle sparing, MS)
This type of surgery can improve patients’ early postoperative pain and reduce the occurrence of pulmonary complications and facilitate recovery by maintaining the integrity of the chest wall muscles as much as possible, and the incision is small and hidden, which is more acceptable to young female patients. The most commonly used surgical approaches are the small axillary incision and the auditory triangle incision.
2.1.1 The small axillary incision, also known as the traditional MS thoracotomy incision, preserves the latissimus dorsi muscle and bluntly retracts the anterior serratus along the muscle fibers, and the only muscle to be cut is the intercostal muscle, which is the most common clinical MS incision. The minimally invasive open chest retractor is used intraoperatively with slow bracing to prevent rib fracture and paravertebral nerve compression.
The small axillary incision does not affect the movement of the latissimus dorsi, rhomboid, rhomboid and anterior serratus muscles, does not cut the ribs, does not pull the scapula, has less impact on the muscles and bones, has less impact on the shoulder joint movement function, and can prevent the occurrence of frozen shoulder in patients after surgery. The incision is located in the central part of the standard postero-lateral incision. When the operation is difficult, the incision can be extended to both ends to become the standard postero-lateral incision.
2.1.2 Auditory triangle incision As the name implies, the surgery is performed using an auditory triangle with no muscle area into the chest, using the gap between the rhomboid muscle and the latissimus dorsi and anterior serratus muscles into the chest, with the base of the triangle being adipose tissue, deep fascia and the 6th rib space (Figure 2). Compared with the traditional MS incision, there is less need for extensive freeing of the flap and the latissimus dorsi muscle to reveal the posterior border of the anterior serratus muscle in traditional MS, so the incision is smaller and the time to enter and close the chest is shorter [7].
Since the operation of MS is similar to traditional open-chest surgery, it was adopted by most thoracic surgeons as soon as it was promoted. With the advancement of instrumental surgery technology and the improvement of surgical operation skills under small incisions, the indications for MS treatment of lung cancer have been expanded, and basically it can cover most lung cancer patients who are suitable for surgery.
2.2 VATS for lung cancer
Thoracoscopic technology is a technological revolution in the development of thoracic surgery second only to extracorporeal circulation [8]. VATS can be divided into three surgical procedures, namely, complete thoracoscopic lobectomy, thoracoscopic-assisted lobectomy, and thoracoscopic-assisted small-incision lobectomy, and a chest incision must be made to remove the specimen in either procedure.
2.2.1 Full thoracoscopic lobectomy (thoracoscopic lobectomy) requires two to four thoracic incisions, including a main incision of 3 to 5 cm for manipulation and specimen retrieval and one to three additional incisions of 1 to 1.5 cm in length, requiring no rib spacers to open the ribs and the surgeon to view the surgical field only through a television screen.
The currently accepted indications for the use of total thoracoscopy are.
① clinical stage I lung cancer;
②Tumor <5 cm;
(iii) Central segmental bronchial lung cancer.
Relative indications.
①Clinical stage II and IIIA lung cancer;
②Tumors >5 cm or too small to be palpable;
③central lung cancer.
Contraindications.
① Chest wall and mediastinal invasion (T3, T4);
②Pre-operative radiotherapy;
(iii) peribronchial lymph node tuberculosis (old). However, complete thoracoscopic surgery often requires the use of disposable surgical instruments, and the cost of expensive consumables is an important constraint to the widespread use of this technology in China.
2.2.2 Thoracoscopic-assisted lobectomy (thoracoscopic-assisted lobectomy or hybrid thoracoscopic lobectomy) The thoracic incision is often 8-10 cm, and a minimally invasive rib spreader is used to open the intercostal space during the operation. Therefore, the indications for surgery are significantly expanded compared with full lumpectomy, and complete resection can be easily achieved for peripheral lung cancer <5 cm, smaller central lung cancer, and those with isolated hilar or mediastinal lymph node metastasis.
Pulmonary angiobronchoplasty and ramus resection and reconstruction can be accomplished through this route by skilled thoracoscopic surgeons. However, this procedure has been criticized by many scholars because it often requires propping up the rib cage and is associated with significant pain in the immediate postoperative period. However, the 8-10 cm incision is a significant improvement over the traditional incision, and most lung cancer surgeries can be performed with conventional surgical instruments, knot tying devices and electrocoagulation hooks, and can be performed with “zero consumables” without increasing the cost of surgery, which is more in line with the national conditions in China and can be easily applied at the local or county level.
Another advantage of hybrid surgery is that the combination of thoracoscopy and small incision technique can be applied to some complex surgeries that are difficult to perform under full thoracoscopy, such as the surgery of central lung cancer whose tumor is too small to be reached or whose tumor stage is too late, and some surgeries that cannot be completed by thoracoscopic operation due to thoracic adhesions.
2.2.3 Thoracoscope-assisted minithoracotomy or video-assisted minithoracotomy (VAMT) is a small thoracic incision of 10-15 cm that requires the use of a rib spreader to open the rib cage, often using conventional surgical instruments. The surgical operation is often performed with conventional surgical instruments, and the operator mostly observes the operative field through the incision.
Combined with thoracoscopic intra-thoracic illumination or observation to deal with areas that are difficult to observe directly, such as the angle of the rib diaphragm or the apex of the chest, it solves the disadvantage of poor visualization of MS surgery and is suitable for most lung cancer patients suitable for surgery. It can utilize lumpectomy instruments or just ordinary surgical instruments, providing more options for different consumer groups.
It is worth mentioning that compared with full thoracoscopic surgery, thoracoscopic-assisted small incision surgery, although more invasive, can significantly reduce the consumption of disposable surgical materials and lower the cost of surgery. Therefore, we believe that individualization should be emphasized in the selection of lumpectomy modality, patient efficacy and safety should be emphasized, and the economics of minimally invasive surgery modality should also be taken into consideration from the national conditions of China, and complete surgery with adjuvant small incision should be chosen when VAMT is more conducive to lesion resection and more cost-effective.
3. Therapeutic effects of minimally invasive surgery for lung cancer
3.1 Feasibility and safety of surgery
Z0030 [9] is a large prospective randomized controlled study conducted by the American College of Surgeons Oncology Study Group from 1999 to 2004 to compare the role of systematic mediastinal lymph node dissection and lymph node sampling in the surgical treatment of lung cancer, which enrolled 1111 patients with early-stage lung cancer, as the majority of the procedures were traditional open surgery;
Therefore, the results of the Z0030 study are now often used as a standard for comparison when discussing the feasibility and safety of lung cancer surgery. To date, the specifics of total thoracoscopic lobectomy reported by McKenna et al. and Onaitis et al. at Duke University have been compared to the Z0030 study.
To clarify the feasibility of thoracoscopic surgery for lung cancer, Gopaldas et al. counted all patients who underwent lobectomy in the US national inpatient database from 2004 to 2006. 13,619 lung cancers underwent lobectomy, 12,860 of which were conventional open-heart surgery and 759 thoracoscopic surgery, and the complication rate in thoracoscopic lobectomy was The incidence of intraoperative complications in thoracoscopic lobectomy was 1.6 times higher than that of conventional open-heart surgery, but there was no significant difference between the 2 groups in terms of immediate operative mortality, length of stay, and cost.
It should be noted that the high rate of intraoperative complications was mainly seen in some physicians who were not skilled in thoracoscopic lobectomy, while the lack of significant difference in hospitalization costs between the 2 groups was mainly related to the use of more disposable consumables in conventional open-heart surgery abroad.
In addition, the CALGB93802 study performed VATS lobectomy in 127 cases of peripheral lung cancer <3 cm and showed that the success rate, mortality, recurrence, and survival of VATS surgery were not significantly different from those of conventional open thoracotomy, and the operative time was slightly longer than that of open thoracotomy, with no significant differences in postoperative complications or 1-year survival. Similar results were obtained in the domestic study.