Minimally invasive surgery (MIS) is a broad term that has a broader connotation than endoscopy, lumpectomy, interventional radiosurgery, small incision, proximal approach, microsurgery, directional guidance surgery, telemedicine, gene therapy, etc. alone. Over the years, controversies over minimally invasive surgery have persisted, mainly due to a one-sided and narrow understanding of the concept of minimally invasive surgery, confusion and disorientation about the relationship between minimally invasive surgery and small incisions, misuse of the concept of minimally invasive surgery, and the shackles of certain traditional concepts. The concept of “simple small incision” is not equal to minimally invasive surgery, which is an incomplete understanding of minimally invasive surgery.
Minimally invasive cardiothoracic surgery, represented by television thoracoscopy (VATS), which was performed in the early 1990s through a few small holes with microscopic cameras and surgical instruments, is certainly a new measure that emerged at the end of the 20th century under the guidance of the concept of minimally invasive and has been welcomed by the majority of patients, but it is only one of the minimally invasive surgeries. The complete concept of minimally invasive surgery requires that special instruments, physical energy or chemicals be delivered into the body through minimal trauma and pathways to complete the removal, repair or treatment of lesions, deformities, tumors, etc. in the body. It requires minimal damage to the body and tissues, and is not limited to which modality or tool is used. In other words, the correct concept of minimally invasive surgery should be a measure that puts the organism in a stable internal environment, after minimal surgical incisions, minimal organ tissue trauma and produces the least systemic and local inflammatory sexual response. Minimally invasive surgery certainly causes significantly less systemic and local damage to the patient (not only based on the size of the incision) than conventional surgery. Some experts believe that in the 21st century, imaging plus minimally invasive surgery (including interventional treatment) will be “equal and equal” to traditional surgery.
Minimally invasive surgical techniques and surgical treatment of lung cancer
The standard procedure for lung cancer is lobectomy, lobectomy sleeve or total pneumonectomy + systemic lymph node dissection, on which there is a consensus. Although this kind of incision provides a fully exposed field of view for lung cancer surgery and can meet most of the requirements of lung cancer surgery, its huge trauma, more bleeding, prolonged opening and closing time of the chest, slow recovery and different degrees of chest pain and shoulder joint movement disorders cause physiological and psychological damage to the patients, which is self-evident. The development of minimally invasive surgery technology provides a better option to solve this problem. Through minimally invasive surgery, the trauma of lung cancer surgery is greatly reduced, postoperative recovery is fast, life quality is significantly improved, and psychological comfort is greater. At the same time, it enables some patients with old age and poor heart and lung function to get the opportunity of surgical treatment. Therefore, the application of minimally invasive surgical techniques in the treatment of lung cancer should be strongly advocated and efforts should be made to improve it. However, it should be emphasized that the application of minimally invasive surgery for lung cancer treatment must also follow the principles of surgical oncology treatment, i.e. maximum complete lung cancer resection and complete lymph node dissection, and it is never advisable to ignore this point and unilaterally pursue “minimally invasive”.
At present, minimally invasive surgery for lung cancer mainly includes three surgical methods, namely, TV thoracoscopic surgery, TV thoracoscopic or image-assisted small-incision direct vision surgery and minimally invasive muscle non-invasive open-heart surgery.
1.Video-assisted thoracoscopic surgery (VATS)
Video-assisted thoracoscopic surgery in the strict sense should be based on thoracoscopic surgical techniques, and the main operations should be performed under non-direct vision. Therefore, the surgery is more difficult and affected by various factors.
(1) Surgical methods of VATS for lung cancer
① Surgical points to be followed.
Anatomical lobectomy should be performed, i.e. pulmonary vessels and bronchi should be dissected and ligated or sutured separately
Systemic lymph node dissection is routinely performed
Avoid rib spreading to reduce postoperative pain
Excised tissue should be removed in a protective bag to avoid dissemination of the incision site
② Surgical approach.
The thoracoscopic trocar is mostly placed in the 7th intercostal space in the mid-axillary line. A better intrathoracic exposure can be obtained by placing the thoracoscope in a lower position in the chest cavity and paying attention to avoid the pericardial fat pad from affecting the visual field.
(2) Indications and contraindications of VATS for lung cancer treatment.
The indications are mainly for patients with stage I peripheral lung cancer <75px< span="">, requiring no serious adhesions in the thoracic cavity and fully developed lung fissures, and the indications can be relaxed when performed by surgeons with extensive experience. Patients with advanced age and poor general condition are more suitable for this type of surgery.
Contraindications mainly include large tumor, central lung cancer, mediastinal lymph node metastasis, and severe thoracic adhesions.
(3) Comparison of VATS and traditional open-heart surgery for lung cancer
(1) Intraoperative comparison: experienced thoracic surgeons performing lobectomy under VATS is the same or better than open lobectomy. there is no significant difference between the time of lobectomy under VATS and that of open thoracotomy. It has been shown that lobectomy under VATS does not increase the risk of intraoperative bleeding.
(ii) Perioperative comparison: VATS lobectomy was associated with significantly lower postoperative pain scores, sedation dosage, need for intercostal nerve block, and sleep disturbance, shorter chest tube retention, and shorter hospital stay compared with open-chest surgical lobectomy.
(iii) Postoperative recovery comparison: Recovery after VATS lobectomy showed less loss of lung function compared with open-chest surgery, including 6-minute walk test, and better partial pressure of oxygen, oxygen saturation, FEV1, and FVC at 7 and 14 days postoperatively than those with open-chest surgery. Quality of life was also significantly improved, with a significantly shorter full return to preoperative activity, higher satisfaction with the size of the incisional scar, a better overall impression of the surgery, and a significant reduction in shoulder joint mobility impairment.
This shows that VATS treatment for lung cancer has the advantages of less trauma, less bleeding, less impact on cardiopulmonary function, safe and reliable, faster postoperative recovery, less complications, reduced postoperative pain, resulting in shorter hospital stay and significantly improved quality of life.
(4) Long-term efficacy of VATS for lung cancer.
The literature reports that the survival rate of VATS pneumonectomy for stage I lung cancer is almost equal to that of conventional open-heart surgery. Large case trials have shown that the long-term efficacy of VATS for stage I lung cancer is satisfactory.
2.Thoracoscopic-assisted minithoracotomy (VAMT)
VAMT is a small intercostal incision made under the assistance of thoracoscope, through which the operator can open the intercostal space and operate under direct vision, which is easier to achieve anatomical lobectomy, and it is more common to perform VAMT lung cancer surgery than VATS in China. The length of intercostal incision usually reaches 200px-375px, which can achieve more satisfactory exposure with the assistance of thoracoscopy, and the operation is more convenient and less demanding for surgeons than VATS surgery, so it is easier to promote. Because of the small incision, the surgical indications are significantly expanded, and complete resection can be achieved for peripheral lung cancer <125px< span="">, smaller central lung cancer, and those with isolated hilar or mediastinal lymph node metastases, and even pulmonary vascular-bronchoplasty and ramus resection reconstruction for central lung cancer can be accomplished by skilled thoracoscopic surgeons, and for systemic mediastinal Lymph node dissection under VAMT can also achieve more thorough results. At the same time, the traditional open lung resection technique can be fully utilized, which greatly reduces the use of disposable instruments and saves considerable costs.
Since lung cancer surgery under VAMT is performed under direct vision and the length of incision is not strictly required, it is believed that if a long small incision is used for VAMT lung cancer surgery, the thoracoscope may mainly play the role of illumination and lose its own advantages and value, in this case, it is more advantageous to use minimally invasive non-invasive muscle open thoracotomy.
3.Minimally invasive non-invasive open thoracotomy (muscle-sparing thoracotomy MST)
(1) Surgical approach of MST for lung cancer
In standard lateral position, a 7-14 cm long incision is made in the lateral chest wall, which can be selected between 3-7 ribs, in order to facilitate the treatment of hilar structures, and for those with chest wall invasion, the incision is biased anteriorly or posteriorly to facilitate the removal of the invaded chest wall. After cutting the skin and subcutaneous tissue, the subcutaneous muscle gap is freed along the diamond-shaped incision, the latissimus dorsi and the serratus anterior are fully freed, the latissimus dorsi is pulled backward, the muscle fibers of the serratus anterior are bluntly separated along the direction to the intercostal surface, the target intercostal incision is made into the thoracic cavity, a small rib spreader is placed, and the surgery is performed under direct vision. Double-lumen tracheal intubation anesthesia is chosen, single-lung ventilation is selected, and satisfactory lung atrophy on the operated side is required to obtain a satisfactory local view, which facilitates the dissection and treatment of hilar structures for lobectomy, total pneumonectomy, and pulmonary sleeve resection. The MST can also facilitate the systematic dissection of mediastinal lymph nodes.
(2) Features of MST for lung cancer
Because the integrity of the latissimus dorsi muscle is preserved in MST for lung cancer treatment, the patient’s postoperative pain is reduced and the impact on shoulder joint movement is greatly reduced. In addition, since the incision is located in the central part of the standard posterior lateral incision, the incision can be extended to both sides to become a standard posterior lateral incision at any time if necessary. With the advancement of instrumental surgical techniques and the improvement of small incision surgical techniques, the indications for MST treatment of lung cancer have increased greatly, and basically it can cover most of the lung cancer patients suitable for surgery.
(3) Prognosis of lung cancer treated with MST
Since MST surgery for lung cancer can satisfactorily perform the same anatomical pneumonectomy and systematic lymph node dissection as traditional open-heart surgery, the cure rate and long-term outcome prognosis should be similar to that of traditional complete lung cancer resection with posterior lateral incision, but there is a lack of rigorous randomized controlled studies.
Minimally invasive techniques and the diagnosis of lung cancer
At present, the most important treatment for non-small cell lung cancer (NSCLC) is surgery. A clear pathological diagnosis is a prerequisite for treatment, and whether lymph node metastasis is a major factor affecting TNM staging and postoperative prognosis. Lung cancer has rich lymph node traffic and is prone to mediastinal and hilar lymph node metastasis, therefore, lymph node metastasis is especially important for TNM staging. Preoperative chest X-ray, chest CT scan, MRI and even PET-CT cannot accurately diagnose lung cancer, and only surgery is the most accurate staging means for lung cancer.
1.VATS surgery
Double-lumen tracheal intubation and intravenous compound anesthesia are used, and the healthy side is ventilated with one lung during the operation. The patient is placed in the standard lateral position. The thoracoscopic lens (secondary operating hole) is first placed in the 7th intercostal space in the mid-axillary line. Intrathoracic exploration is performed to understand the location of the lesion, whether there is tumor invasion or metastasis in the pleura, pericardium, hilar structures and mediastinal lymph nodes. Then, the main operating incision and another secondary operating hole will be designed according to the specific situation.
I. For patients with preoperative diagnosis of lung cancer but unable to obtain pathology, the easiest and least invasive site for biopsy can be sought, either a primary lung lesion, an implanted pleural node, or a highly suspicious lymph node or pleural fluid.
Second, mediastinal lymph node biopsy is performed as a supplement to standard mediastinoscopy (especially group 6 lymph nodes) or when mediastinoscopy is contraindicated, in order to perform accurate lung cancer staging and then adopt the appropriate treatment according to the lung cancer staging.
2.Mediastinoscopic surgery
The size of mediastinal lymph nodes is still the main method of CT diagnosis to determine whether the lymph nodes are metastatic or not. A large number of studies have found that the false positive rate of CT in determining whether the mediastinal lymph nodes are metastatic is 40%. For patients with cN0 and 1, mediastinoscopy does not have a meaningful impact on the complete resection rate, N2 detection rate and complete resection rate of N2 patients in all these patients. However, for cN2 patients, a significant change in treatment strategy is involved, and thus, transjugular mediastinoscopy (conventional procedure) is recommended to determine the treatment strategy by definitive staging.
Procedure: Tracheal intubation is completed in the operating room under general anesthesia, a suprasternal notch incision is made, and a mediastinoscope is inserted along the paratracheal tube to reach the appropriate location for mediastinal lymph node biopsy.
In the distribution of mediastinal lymph nodes in lung cancer, paratracheal lymph nodes (2 and 4 groups of lymph nodes), anterior tracheal lymph nodes (1 and 3 groups of lymph nodes) and subserosal lymph nodes (7 groups of lymph nodes) can be examined by cervical mediastinoscopy to determine whether they are metastatic. The aortic window lymph nodes and ascending aortic lymph nodes (groups 5 and 6 lymph nodes) can be determined by parasternal mediastinoscopy, while the lower mediastinal lymph nodes (groups 8 and 9 lymph nodes) are blind to mediastinoscopy.
3.Echo-bronchoscopy (EBUS) and EBUS-TBNA (endobronchial ultrasound-guided needle aspiration biopsy)
EBUS is a device with an ultrasound probe installed at the front end of the bronchoscope. Combined with a special suction biopsy needle, transbronchial needle aspiration biopsy (TBNA) can be performed under real-time ultrasound guidance, and the color energy Doppler with the electron convex array scanning on board can help confirm the location of blood vessels at the same time and prevent misperforation of blood vessels, which is highly accurate in diagnosing lung cancer. EBUS-TBNA can be used to diagnose lung cancer by puncturing the hilar and mediastinal metastatic lymph nodes, as well as by directly puncturing a paratracheal mass. Several studies have shown that the average sensitivity of EBUS-TBNA for lung cancer diagnosis is 90% and the false-negative rate is 20%. In contrast, the sensitivity of lung cancer diagnosis using conventional TBNA is only about 65%. Preoperative lung cancer staging is the most important application of EBUS-TBNA in the field of lung cancer, and it has been recommended by the National Comprehensive Cancer Network (NCCN) and the American College of Chest Physicians (ACCP) as an important tool for preoperative lymph node staging of lung cancer in 2007. NSCLC guidelines also pointed out that lymph node metastasis should be evaluated before stage III N2-3 treatment, and even PET-CT-positive LN requires pathological basis for confirmation.
EBUS-TBNA lung cancer staging has been shown in several studies to be highly sensitive compared to CT and PET in mediastinal staging, and complications are rare with EBUS-TBNA, which compares favorably with mediastinoscopy, the traditional gold standard for evaluating mediastinal lymph node metastases. As a surgical procedure, mediastinoscopy is more costly, requires general anesthesia, hospitalization, and has associated complications and mortality, whereas EBUS-TBNA is non-invasive, less expensive, does not require general anesthesia, and can be performed on an outpatient basis with few complications. The only two prospective controlled studies comparing preoperative EBUS-TBNA and mediastinoscopy for lymph node staging of lung cancer in the same case showed that EBUS-TBNA was more sensitive, negative predictive value, and accurate than mediastinoscopy for patients with high lymph node metastasis (89% for N2 or N3) and for patients with moderate lymph node metastasis (39% for N2 or N3). The sensitivity, negative predictive value, and accuracy of EBUS-TBNA were slightly lower than those of mediastinoscopy.
4. EUS-FNA (transesophageal ultrasound endoscopy-guided needle aspiration biopsy)
For progressive lung cancer with hilar or mediastinal lymph node metastasis and lung cancer adjacent to esophagus, transesophageal aspiration biopsy of lymph nodes or tumor under endoluminal ultrasound guidance can be performed for diagnosis and staging of some lung cancer patients. Before puncture, ultrasound endoscopic mediastinal scan is first performed to understand the size and shape of the lesion and its location in the mediastinum through different scan frequencies and scan directions; then, transesophageal puncture is performed under ultrasound guidance. During the puncture, the color Doppler effect and the adjustment of the direction of the puncture needle can effectively avoid the blood vessels and normal organs in the mediastinum. Based on the transesophageal route, mediastinal lymph node biopsy near the esophagus is more appropriate. Lymph nodes that are difficult to reach by mediastinoscopy (groups #3p, #5, #8, #9) are suitable for EUS-FNA biopsy, which can compensate for the shortcomings of mediastinoscopy or EBUS-TBNA. The accuracy rate of the lung cancer diagnosis and staging derived from this method was 99.2%, with a positive compliance rate of 100% and a negative compliance rate of 96.5% when compared with the pathological results after surgery.
5. Combined application of EUS-FNA with mediastinoscopy
However, due to the interference of the trachea, the anterior superior mediastinum area located in front of the trachea belongs to the blind area of transesophageal endoluminal ultrasound scanning. Transjugular mediastinoscopy is the most frequently used invasive means in determining the nature of the anterior tracheal space lymph nodes and the anteriorly deviated subserosal lymph nodes, and its accuracy rate is 93.6%, so transesophageal endoluminal ultrasound and mediastinoscopy can complement each other to improve the sensitivity of diagnosis.
6.EUS-FNA and EBUS-TBNA
Several studies have shown that the combination of EUS-FNA and EBUS-TBNA has a sensitivity of 97% and a false-negative rate of 2% in patients with lung cancer with mediastinal metastases, and that the completion of EUS-NA and EBUS-NA in one visit is very effective in improving the efficiency of diagnosis.
In conclusion, the rapid development of minimally invasive technology has led to the expansion of its application in the treatment of lung cancer, and with the unremitting efforts and exploration of clinicians, it will definitely become a new trend in future surgery.