Lung cancer is one of the most common malignant tumors that seriously endangers human health and life. Regardless of men and women, its mortality rate ranks first among malignant tumors, and is a malignant tumor with mortality rate very close to the incidence rate. In Shanghai, Beijing, Tianjin and other places, lung cancer has ranked first in the incidence rate of malignant tumors. It is generally believed that the development of lung cancer is mainly caused by environmental factors. When it comes to lung cancer, people always think of smoking, and indeed, the occurrence of lung cancer is closely related to smoking. However, in real life, we often see that some people die of lung cancer even though they have never smoked, while some people live a long life even though they swallow fog all day long. In fact, it is not difficult to explain that although smoking is the main cause of lung cancer, it is not the only cause. The occurrence of lung cancer is the result of multiple factors, including smoking, passive smoking, occupational exposure, air pollution, family genetics, etc., which are closely related to lung cancer. The prognosis of this disease is very poor, about 80% of patients die within one year after diagnosis because many patients are at advanced stage at the time of diagnosis. The earlier the treatment, the better the prognosis. The main symptoms of lung cancer are as follows: 1. Cough: The most common self-reported symptom of lung cancer patients is cough, which is the first symptom of about 60% of patients. It is mainly a dry cough with paroxysmal irritation, no sputum or only a small amount of white foamy sputum. Hemoptysis: This is a typical clinical manifestation of lung cancer patients, and also one of the common first symptoms. About 30% of patients have this symptom for the first time. It is usually sporadic sputum with blood spots or blood shreds. 3. Chest pain: It is a common symptom in early stage lung cancer patients, and 20%-30% of patients have this first symptom. Different parts of the tumor may produce different pains, such as irregular dull pain or hidden pain in the chest; chest pain with obvious pressure points; pain that worsens with breathing, coughing and changing position, etc. 4.Shortness of breath and difficulty in breathing in the chest: often caused by multiple reasons. Many lung cancer patients have different degrees of chronic lung diseases, and the occurrence of lung cancer will lead to the aggravation of the original symptoms; in addition, if the tumor is located in large bronchial tubes, it can lead to their narrowing and obstruction, which will affect breathing, etc. 5.Fever: Lung cancer can cause obstructive pneumonia and fever, which can be relieved by antibiotic treatment in many patients; in addition, tumor itself can also cause cancer fever, which is often persistent and antibiotic treatment may be ineffective. 6.Weight loss: It is a common symptom and not necessarily a manifestation of advanced stage. 7.Other: lung cancer may cause accompanying tumor syndrome, such as neuromuscular disease (myopathy syndrome, etc.), acanthosis nigricans, hypertrophic osteoarthropathy, endocrine changes (Cushing syndrome, carcinoid syndrome, etc.). The symptoms produced by lung cancer are very similar to those of cold, pneumonia, bronchitis, etc. and can easily be overlooked. Therefore, for people with high-risk factors, they must be alert to the above-mentioned symptoms and should seek medical attention as soon as they find similar symptoms. Through relevant examinations such as chest X-ray, CT, fibrinoscopy, etc., lesions can be detected in time and diagnosed at an early stage. Only in this way can we win more time in the battle against cancer and increase the survival rate.