Lung cancer is a common primary malignant tumor of the lung, which can usually be detected through specific clinical manifestations, related triggers, and medical examinations such as chest X-ray, CT, tumor marker detection, pathological tissue biopsy, etc. to help exclude the lesion.1. Clinical manifestations: Patients with lung cancer may have no obvious symptoms in the early stage and are mostly found when chest X-ray or CT examination is performed. With the development of the disease, different symptoms may appear, including cough, bloody sputum, chest pain, fever, shortness of breath, wasting, etc. If the disease invades the surrounding tissues in advanced stage, symptoms such as hoarseness, jugular vein anger, difficulty in swallowing, etc. may also appear. 2. Medical examinations: Imaging examinations include chest X-ray, CT, ultrasound, MRI, endoscopy, pathology and blood test, which are helpful to detect suspicious lesions and judge their size and morphology. Among them, chest X-ray can detect more typical nodular lesions in the lung, chest CT can detect microscopic lesions, and ultrasound can help to stage lung cancer at the same time. Pathological examination has certain diagnostic significance in excluding lung cancer, which can be clarified by pleural effusion, sputum exfoliative cytology, superficial lymph node biopsy, lung biopsy, etc. There are also endoscopic examinations, such as tracheoscopy often combined with pathological tissue biopsy, which can identify the benign and malignant nature of tumors. Blood tests for tumor markers, including carcinoembryonic antigen, neuron-specific enolase, squamous cell carcinoma-associated antigen, cytokeratin 21-1, and glycoconjugate antigen 125, can be used for screening and assessment of treatment of neoplastic diseases such as lung cancer. In addition, if there are respiratory symptoms such as dry cough and bloody sputum that cannot be cured for more than 2 weeks, you need to be alert to the possibility of lung cancer and should go to the hospital for examination as soon as possible. Early detection and treatment can increase the possibility of cure and avoid further development of the disease and increase the difficulty of treatment.