Many countries have reported a significant increase in the incidence of lung cancer in the last 50 years. Smoking is the most important risk factor for lung cancer. Long-term heavy smokers are 10 to 20 times more likely to develop lung cancer than non-smokers, and the younger the age of starting to smoke, the higher the chance of developing lung cancer. Smoking not only directly affects one’s own health, but also has a negative impact on the health of the surrounding population, leading to a significant increase in the prevalence of lung cancer in passive smokers. Second, occupational and environmental exposures, now aluminum by-products, arsenic, asbestos, chromium compounds, coke ovens, mustard gas, nickel-containing impurities, and vinyl chloride. Furthermore, air pollution, especially industrial exhaust and ionizing radiation can trigger lung cancer. Finally, the development of lung cancer is also influenced by genetic factors. What are the symptoms that indicate the possibility of lung cancer: Early symptoms of lung cancer are often mild and may not even cause any discomfort. The symptoms of lung cancer are broadly divided into: local symptoms, systemic symptoms, extra-pulmonary symptoms, infiltration and metastasis symptoms. (I) Local symptoms: For patients who smoke or suffer from chronic bronchitis, if the cough is aggravated, frequency is increased, and the nature of the cough is changed such as a high-pitched metallic sound, especially in the elderly, they should be highly alert to the possibility of lung cancer. Blood in sputum or hemoptysis, chest pain, chest tightness, shortness of breath and hoarseness may also be early signs. (b) Systemic symptoms include unexplained fever, wasting and cachexia. (iii) Extrapulmonary symptoms: They can often appear before other symptoms and may subside or appear with the growth of tumor. Clinically, osteoarthritis of pulmonary origin is more common, which is related to certain special active substances (including hormones, antigens, enzymes, etc.) produced by lung cancer. (iv) External invasion and metastasis symptoms such as lymph node enlargement, bloody pleural fluid, facial swelling, etc. How to confirm the diagnosis in suspected patients: Depending on the patient’s condition, it may be necessary to complete chest enhancement CT, bronchoscopy pulmonary puncture, thoracotomy, thoracoscopy and other examinations. After the pathological diagnosis is confirmed, whole body examination is often needed to clarify the early and late stage of lung cancer. With the advancement of technology, cancer is no longer an incurable disease. Surgery is preferred for early stage squamous lung cancer, chemotherapy is very effective for most small cell lung cancer, and targeted drugs may be suitable for adenocarcinoma patients in addition to surgery as much as possible. Of course, some patients may also be suitable for new treatment methods such as biologic therapy and particle implantation therapy. What are the frequent side effects of chemotherapy: Patients in the interval between chemotherapy and radiotherapy need to check their blood routine every 3 days. If there is a decrease in white blood cells, hemoglobin or platelets or if there is severe fever, diarrhea or vomiting, they need to go to the hospital promptly. What can be done to prevent lung cancer: The best treatment for lung cancer is to prevent it, which can be prevented and controlled. Preventive measures include prohibiting and controlling smoking, protecting the environment, avoiding exposure to occupational carcinogenic factors, scientific diet, increasing vegetables and fruits in the diet, etc.