At present, lung cancer is recognized as the number one killer of human life today, because its incidence and mortality rate have jumped to the top of all kinds of malignant tumors. There is a lack of effective methods for early diagnosis of lung cancer, and 80% of lung cancer patients are already in advanced stages once they are detected and lose the best time for treatment. According to the information published by the World Health Organization (WHO), the global cancer incidence and death have increased by about 22% in the past few years, among which lung cancer is the most important cancer in the world, both in terms of the number of incidence (1.2 million M-year) and the number of death (1.1 million M-year). Lung cancer is particularly dangerous because of its high mortality rate of 90%. It is projected that the global population will reach 8 billion in 2020, and the number of new cases and deaths of lung cancer will continue to climb to 2.4 million and 2.1 million per year, respectively. In China, lung cancer is also the number one cancer, accounting for more than 20% of cancer deaths, and the incidence and mortality rates are growing rapidly. The overall 5-year survival rate is around 10%, and it is one of the major lethal diseases. Lung cancer has seriously hindered the development of national economy and become one of the most difficult and important problems in cancer prevention and treatment in the new century in China. The etiology and risk factors of lung cancer are well studied, in order of smoking, occupational hazards, atmospheric pollution and genetic susceptibility. Smokers are younger, leading to a younger age of lung cancer, with a significant increase in the incidence of patients aged 40-50 years compared to the previous; control of smoking is imperative. The causal relationship between smoking and cancers such as lung cancer has been established in numerous epidemiological studies worldwide, providing the best opportunity to date for human cancer prevention. Smoking control reduces lung cancer by approximately 80%, and cancer deaths by 30%. Early stage lung cancer treatment is more satisfactory, with a five-year survival rate of about 80%, some of whom can survive for a long time; while the five-year survival rate for advanced stage is only about 6%. Therefore, early detection, early diagnosis and early treatment are especially important, and people over 40 years old should have annual health checkups to eradicate the disease at its early stage. What is lung cancer? Lung is the respiratory organ of human body, which consists of trachea, bronchi at all levels and alveoli. Malignant tumors occurring in bronchi and alveolar epithelial cells are called lung cancer. Clinically, according to the location of tumor growth, there are central type lung cancer and peripheral type lung cancer. Those occurring above grade 3 bronchi are called central lung cancer, while those occurring below grade 4 bronchi are called peripheral lung cancer. Lung cancer is one of the most threatening malignant tumors to the health and lives of occupational groups in the world today. Worldwide, it accounts for 1 million new cases each year and tops the male tumor mortality rate. The incidence of lung cancer continues to show an increasing trend in many countries. The recent increase of lung cancer incidence among women is related to the increase of smoking and passive smoking among women as well as the environmental pollution caused by air pollution in small kitchen environments and home renovation. Early lung cancer clinical symptoms are not obvious. Lung cancer growing in the bronchus mostly manifests as irritating cough, coughing sputum, blood in sputum, or different symptoms due to tumor invasion to different tissues and organs around. Peripheral lung cancer usually has no symptoms in early stage or only limited transient chest pain. Late stage lung cancer may cause corresponding symptoms: gradually increasing dysphagia due to compression or invasion of esophagus, hoarseness due to compression of laryngeal nerve, superior vena cava syndrome due to compression or invasion of superior vena cava: dyspnea, purple lips and fingertips with facial and neck edema, dilated veins of chest wall, ipsilateral upper limb edema, etc. When peripheral lung cancer invades local pleura, ribs or intercostal nerve, it can cause pain in the corresponding area; when the pleura is widely invaded, malignant pleural fluid can be formed. Tumors near the spine may directly invade the vertebral body or cause local pain or other corresponding symptoms due to bone metastasis. What tests are needed after suspected lung cancer diagnosis If you have symptoms such as cough, hemoptysis and chest pain, you should go to hospital immediately. After a comprehensive physical examination and obtaining valuable positive signs, doctors should also conduct chest imaging examinations, including chest X-ray and CT, etc. If lung cancer is suspected, bronchoscopy should be performed. CT or MRI of head, whole body bone and medical examination (ECT), ultrasound or CT of liver and adrenal glands should be performed before surgery for early and intermediate stage patients to exclude distant metastases. If necessary, biopsy of lesions or metastases, mediastinoscopy or thoracoscopy and/or sputum cytology should be performed to clarify the pathological histological or cytological diagnosis. Even if the pathological or cytological diagnosis is correct, treatment should be based on a thorough systemic examination to determine the stage. In some cases, early stage peripheral lesions that appear to be resectable may be detected as asymptomatic brain or bone or other advanced (stage IV) metastases after comprehensive systemic examination, and surgical treatment may not prolong survival at this time. Therefore, a comprehensive systemic examination must be performed before surgery to determine the absence of distant metastases before surgical treatment. Peripheral type lesions that can be operated on should preferably be operated on directly without focal puncture to prevent local tissue implantation and dissemination of cancer cells that may be caused by puncture. If possible, whole-body PET-CT examination can be performed to detect microscopic lesions of about 3mm throughout the body. 4.What are the types of lung cancer resection and how to make the choice Like other solid tumors, surgery is still the main treatment for early and middle stage lung cancer, and it is also the possible means to cure lung cancer. Lung cancer lung resection surgery should abide by the two principles of “maximum”, “maximum” lung tumor removal and “maximum” lung function preservation. At the same time, the lymph nodes in the chest cavity should be thoroughly cleared. Common lung cancer resection procedures: (1) lobectomy/double lobectomy + lymph node dissection: this procedure is the standard lung cancer resection, which is in line with both surgical and oncological principles, with reliable efficacy and few complications. (2) Total pneumonectomy: Removal of half of the human lung tissue has a certain impact on survival quality after surgery, so right total pneumonectomy is generally avoided as much as possible, but total pneumonectomy is still the best choice when the tumor is centrally located and accumulates to large blood vessels or main bronchi. Therefore, this procedure is suitable for patients with central lung cancer who can tolerate total pneumonectomy. (3) Partial pneumonectomy and a-pneumonectomy: A small portion of the lung tissue is removed. This procedure is suitable for patients with peripheral and very early stage lung cancer, or those with early lesions and combined cardiopulmonary dysfunction who cannot tolerate lobectomy, and is also commonly used for locally recurrent or metastatic lung cancer. (4) Bronchoplasty pneumonectomy, which is a more complicated and risky operation, is limited to large hospitals with experience in bronchoplasty. (5) Thoracoscopic minimally invasive incision radical lung cancer surgery, which is less traumatic and faster recovery, with the maximum incision only about 3.5cm, is a high technology surgical method that has been gradually promoted since 2007. V. What is adjuvant chemotherapy, the purpose, necessity and duration of adjuvant chemotherapy Lung cancer is a systemic disease, even in early stage, there may still be hidden metastases in other parts of the body, and any single local treatment cannot eliminate these metastases. This is why some patients with early stage lung cancer and complete surgical resection will still have metastasis and recurrence. The chemotherapy administered to reduce the chance of metastasis or recurrence after surgery or radiotherapy is called adjuvant chemotherapy. It is mainly for patients whose primary tumor has been resected or after radical radiotherapy, and metastasis is not detected with the existing clinical detection methods. A large number of experimental studies have proved that the lower the number of cancer cells, the more sensitive chemotherapy is and the better its efficacy. Therefore, after the primary lesion is removed as the main tumor load by effective local treatment (i.e. after surgery or radiotherapy), chemotherapy should be administered as early as possible with the most effective drug to maximize the elimination of residual tumor cells in order to reduce recurrence and metastasis. According to foreign clinical trials, there is no difference in 5-year survival rate between 4 cycles of postoperative adjuvant chemotherapy and 6 or more cycles of chemotherapy compared to 4 cycles of adjuvant chemotherapy, and the 5-year survival rate is lower than that of patients receiving 4 cycles of chemotherapy. Therefore, it is currently believed that adjuvant chemotherapy should be administered within 2 to 4 weeks after surgery or radiation therapy, and that 4 cycles of chemotherapy should be completed within 4 to 6 months.