Since the 1980s, lung cancer has become the cancer with the highest incidence and mortality rate worldwide, and the trend is increasing year by year. In China, lung cancer in Beijing, Shanghai, Guangzhou and Hefei has jumped to the top of the group of cancers, and the incidence rate increases rapidly after the age of 40. The prevalence rate of men and women is 2.3:1, and race, family history and smoking have an impact on the incidence of lung cancer. The treatment of lung cancer differs according to the pathological type and location of the disease. 1. Pathological typing: According to pathological types, lung cancer can be divided into small cell lung cancer and non-small cell lung cancer (which includes squamous carcinoma, adenocarcinoma, large cell carcinoma, etc.). Chemotherapy is preferred for small cell lung cancer, along with systemic chemotherapy and chest radiotherapy. After complete remission, prophylactic brain radiotherapy may also be administered. A combination of chemotherapy, radiotherapy and surgery can also be used for limited small cell lung cancer, while chemotherapy and radiotherapy are the main treatment options for extensive small cell lung cancer. For non-small cell lung cancer, surgery is preferred, and neoadjuvant chemotherapy can be given before surgery, followed by radiotherapy or chemotherapy after surgery. If the patient has no indication for surgery, chemotherapy, radiotherapy and minimally invasive treatment will be performed. 2. Site of origin: According to the site of origin, lung cancer can be divided into central lung cancer (cancer occurring in the main trachea, main bronchus and segmental bronchus) and peripheral lung cancer. According to TNM stage, those with surgical indications in early stage should strive for surgical treatment, while those without surgical indications in late stage can adopt minimally invasive treatment methods based on bronchoscopic examination results, including microscopic treatment and percutaneous puncture treatment. Minimally invasive treatment techniques for intra-airway tumors 1. Cryotherapy: The commonly used freezing equipment is CO2 freezer, which can be inserted into the lesion under the guidance of hard bronchoscopy or soft bronchoscopy and freeze the tumor to death. Research results show that cryotherapy is very effective for soft bronchial luminal tumors and low-grade malignant tumors such as cylindrical tumors and carcinoid tumors, and has a certain hemostatic effect on tumors with rich blood vessels or those with hemoptysis. It may be better than laser treatment for infiltrative lesions in the bronchial lumen or luminal stenosis of longer scope, but should be used with caution for severe airway stenosis when the lumen has been reduced by more than 50%. When lung cancer grows in the bronchial cavity and severely obstructs the airway, causing whistling distress, obstructive pneumonia and pulmonary atelectasis, cryotherapy can be performed via bronchoscopy to unblock the airway, improve the ventilation function and drain airway secretions. The effect of cryotherapy is slow, unlike laser therapy and electrocoagulation and electrodesiccation therapy, which are effective immediately. Therefore, laser or electrocoagulation and electrosurgery are preferred for patients with acute severe airway obstruction. It has been shown that the combination of cryotherapy and chemotherapy or radiotherapy has a synergistic effect and can improve the quality of life and prolong the survival time of patients. 2.Thermal therapy: including laser, high-frequency electric knife, argon knife, microwave, etc., can rapidly reduce the tumor, open the airway and relieve the obstruction symptoms. For those with larger tumors and more obvious inspiratory difficulties, thermal therapy should be preferred to reduce the degree of lumen obstruction, and then cooperate with radiotherapy, photodynamic therapy and local chemotherapy, etc., and if necessary, cooperate with internal stent therapy. 3.Local drug injection in the tracheal lumen: for those who are clearly malignant endotracheal tumors, they can be treated with cryotherapy, thermotherapy, intra-tumor injection of chemotherapy drugs, interleukin-2, genetic drugs, etc. to play a synergistic role. 4.Photodynamic therapy (PDT): PDT can achieve radical effect on early tracheobronchial cancer, and for cancer foci confirmed as superficial damage by ultrasound examination, complete cure may be achieved by bronchoscopic PDT. For advanced tumors, it plays a palliative treatment tool. For larger intracavitary tumors before photodynamic therapy, freezing or thermal ablation can be used to reduce the thickness of the lesion before PDT, which often improves the efficacy. The method of PDT is simple: inject photosensitizer into the patient’s vein beforehand, insert fiber optic into the lesion site in the trachea under the guidance of tracheoscope 24~48 hours later, then irradiate with specific wavelength laser (usually 630nm or 650nm) for 5~30 minutes, and repeat the irradiation again on the second and third day (usually 2~3 times a course). On the second day after irradiation, necrotic material can be seen on the surface of the tumor, which should be removed by tracheoscope in time to avoid blocking the airway and causing asphyxia. According to foreign reports, the recent clinical cure rate of stage I lung cancer patients after PDT reached 100%, and all of them were alive at 2 years of follow-up, and 88% survived for more than 5 years; the median survival of stage II, IIIA, IIIB and IV was 22.5 months, 5.7 months, 5.5 months and 5.0 months, respectively, and the remission time and quality of survival were as good as most of the reported therapies. It has also been reported that the obstruction level of endotracheal non-pulmonary tumor metastases decreased from 85% to 13% after PDT, with significant improvement in dysphagia, hemoptysis, cough and quality of survival, as well as significantly longer survival time. 5.Intracavitary brachytherapy: There are usually two methods. One is intracavitary brachytherapy, which is to deliver the source applicator or source guide tube with isotope to the appropriate lesion site, verify the location by X-ray, and then calculate and optimize the dose distribution by the treatment planning system to obtain satisfactory results and then carry out the treatment. The advantage of post-mounted brachytherapy is that the patient can receive precise treatment and the medical staff can operate remotely from a room, which is very safe. There is also radioactive particle implantation, which usually involves strapping radioactive particles to an endoprosthesis to both support the narrowed trachea and provide brachytherapy to control further growth of the tumor. 125I particles can also be implanted directly into large tracheal tumors that cannot be removed surgically under direct bronchoscopy to relieve clinical symptoms such as airway obstruction and obstructive pneumonia caused by tumors in the large airways, and the local control rate of tumors can reach 85%. 6.Endotracheal stent placement: It is suitable for tracheal stenosis caused by invasion or compression of tracheal, esophageal and mediastinal malignant tumors; tracheal stent placement can be considered for those who cannot have esophageal stent placement for high esophageal-tracheal fistula. Metal tracheal stent placement for the treatment of tracheal stenosis can rapidly relieve the inspiratory difficulties and significantly improve the clinical symptoms, blood gas analysis and pulmonary function test results, and the abnormal indexes due to tracheal stenosis can return to normal within 3-5 days. Fully laminated tracheal stents can be left in the trachea for a long time. Currently, the commonly used tracheal stents in China are nickel-titanium memory alloy mesh stents and Z-type stainless steel stents. They are available with or without membrane (bare stent), and silicone stents. According to the shape, they are further divided into straight stents and bifurcated stents. The placement of the stent is simple. The guidewire can be delivered to the predetermined site under X-ray fluoroscopy or bronchoscopic guidance, and then the endoprosthesis deliverer is placed along the guidewire over the lesion, and then the endoprosthesis is released at a certain depth to ensure that the endoprosthesis holds up the entire lesion. 1.Insert the guidewire 2.Insert the stent pusher along the guidewire 3.Stent reach the predetermined site 4.Release the endoprosthesis