1.5％ of lung cancer patients have no symptoms at the time of consultation. 2.Symptoms of lung cancer invasion and metastasis (1) Superior vena cava obstruction syndrome. 5-10% of patients present to the doctor with this as the first symptom. It is manifested as edema of upper limbs and edema of head and face, etc. (2) Horner syndrome. This syndrome is characterized by sunken eyeballs, drooping upper eyelids, smaller eye fissures, reduced pupils, and absence of sweating on the affected side. (3) Pankow syndrome. The tumor invades the brachial plexus nerve and causes pain in the upper limbs. There are also invasion of laryngeal recurrent nerve causing hoarseness, and brain, bone, liver and subcutaneous metastasis. All of these are the late manifestations of lung cancer. Diagnosis of lung cancer 1.X-ray examination. There are many early stage patients without any symptoms, but the mass can be seen on the X-ray film. 2.CT examination. After lung mass is found, further CT examination should be performed. Plain scan can reveal the relationship between the mass and surrounding tissues, and enhanced scan can reveal the relationship between the mass and surrounding large blood vessels and the enlarged lymph nodes. In addition, CT examination of head should be done when lung cancer is suspected to clarify whether there is brain metastasis.