Lung cancer is the most common malignant tumor, and its incidence and mortality rate are the highest among malignant tumors, and its incidence rate is still on the rise. The incidence of lung cancer is characterized by a higher incidence rate in men than in women (but the incidence rate in women has been increasing faster in recent years), a higher incidence rate in urban than in rural areas, and a higher incidence rate in developed and industrialized areas than in poor and backward areas. The causes of lung cancer are related to genetic factors, inhalation of tobacco, atmospheric and indoor environmental pollution, occupational exposure to carcinogens, tuberculosis infection and other factors. Lung cancer has a high degree of malignancy and a poor prognosis. In the United States, the 5-year survival rate for lung cancer increased by less than 10% between 1975 and 2005, despite significant human, material and financial resources. Early detection of lung cancer and surgery is currently the only way to cure lung cancer. Therefore, early manifestations and symptoms of lung cancer should be paid attention to, and early consultation should be made when suspicious symptoms appear. Clinical manifestations Cough, coughing blood and chest pain are the early manifestations and also the most common symptoms of lung cancer. 1. Cough: It is the most common symptom and is often treated as “cold” and “bronchitis”, so it is easy to be ignored. If cough or irritating choking cough persists for a long time, you should go to hospital for examination in time. 2.Coughing up blood or blood in sputum: once it occurs, high attention should be paid to it. 3. Chest pain: caused by lung cancer invading the pleura or chest wall. 4.Thoroughness and shortness of breath: Most of them are caused by airway obstruction. Late stage lung cancer with large amount of pleural fluid or pericardial effusion may also cause chest tightness and shortness of breath. 5.Heartness of voice: Invasion of the recurrent laryngeal nerve may cause hoarseness of voice. 6.Facial and neck swelling: a manifestation of superior vena cava compression. 7. Systemic symptoms: fever, emaciation, fatigue, weakness, anemia, etc. 8.Pestle and pestle finger and painful enlargement of bone and joint, etc. Diagnosis (a) Common examination methods 1.Tumor marker test: blood can be drawn for CEA, NSE and other tumor markers. 2.Sputum cytology examination: simple and non-invasive, but the positive rate of one examination is often not high, so it is recommended to have several consecutive examinations. 3.Chest X-ray: frontal and lateral chest films are not effective in detecting early lesions and those located in hidden areas such as mediastinum. 4.CT examination of the chest: divided into plain scan and enhanced, which shows better for lung lesions. 5.Magnetic resonance imaging (MRI) of the chest: the lung lesions are not as well displayed as CT, but the mediastinum is better displayed. 6.PET-CT examination: it can better detect lung and metastatic lesions, but still cannot confirm the diagnosis of lung cancer, and is more expensive. 7.Fibrinoscopy: It has greater diagnostic value for central type lung cancer and can confirm lung cancer through biopsy. 8.Mediastinoscopy: It is suitable for those whose lung lesions are difficult to be characterized but have enlarged mediastinal lymph nodes. 9.Thoracoscopy: suitable for biopsy of peripheral lung lesions and removal of small lesions. 10.Transcutaneous lung aspiration biopsy: it is valuable for the pathological diagnosis of peripheral lung cancer. 11.Lymph node biopsy: excision of lymph nodes in the neck or mediastinum or biopsy needle to obtain tissue for pathological examination. 12.Pathological examination: It is the gold standard for lung cancer diagnosis. Pathological examination is divided into cytological examination and histopathological examination. Cytological examination can confirm the diagnosis of lung cancer once cancer cells are found through examination of sputum, pleural fluid and fine needle aspirate, but the positive rate of cytological examination is relatively low. Histopathological examination refers to microscopic observation after paraffin embedding, sectioning and staining of biopsies or surgically excised specimens, and immunohistochemical examination can further clarify the type of pathology. Molecular pathology and genetic testing are of great value to understand the characteristics of lung cancer and to know the molecular targeted therapy. (B) Lung cancer staging 1. Clinical staging: divided into central type and peripheral type. The central type is located above the bronchus of the lung segment (excluding the lung segment), and this type often has obvious cough and coughing blood. The peripheral type is located below the bronchus of the lung segment (including the lung segment). 2.Pathological typing: usually divided into small cell lung cancer (about 20%) and non-small cell lung cancer (about 80%). Non-small cell lung cancer also includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Small cell lung cancer is more malignant, prone to metastasis and has a poor prognosis, with an average survival of about six months. Non-small cell lung cancer has an average survival of about one year, and mainly adopts surgery-based comprehensive treatment in early stage. 3.Lung cancer staging: there are international TNM staging and clinical staging. TNM staging: T stands for primary tumor, N stands for lymph node metastasis, M stands for distant metastasis, followed by Arabic numbers indicating tumor size and infiltration and metastasis. Clinical stage: divided into 4 stages, indicated by Roman numerals Ⅰ, Ⅱ, Ⅲ and Ⅳ, such as stage Ⅰ is early stage, stage Ⅳ is late stage, and stages Ⅱ and Ⅲ are in between.