As we all know, cough that is not cured for a long time is a typical symptom of lung cancer. However, in the early stage of lung cancer, coughing symptoms are not obvious, and some patients even do not cough at all. The first symptoms of some lung cancer patients are commonly bone and joint pain, neck swelling, vague pain in upper abdomen, loss of appetite, headache and so on. Such patients often consult orthopedic surgery, physical therapy, infectious disease, etc., and miss the best time for lung cancer treatment. Especially for patients with smoking history, if they have unexplained bone and joint pain and headache, they should think about the possibility of lung cancer even if they do not have respiratory symptoms such as cough. In addition, breast enlargement in men may also be a symptom of lung cancer because the abnormal symptoms of lung cancer are likely to be caused by gonadal hormones, and the symptoms of breast development usually disappear after tumor removal. Therefore, adult males with breast development should pay attention to the possibility of tumor and have a chest examination as soon as possible. 1% of lung cancer patients may also have phlebitis, and 3% to 3.5% of thrombophlebitis patients have cancer associated with them, and 1/3 of them also have no symptoms such as cough before the diagnosis of lung cancer. Therefore, patients with unexplained or wandering phlebitis, especially when anticoagulation therapy is not effective, should be alerted to the possibility of malignant lesions. Some lung cancer patients will also present with skin abnormalities, such as marked tenderness in the thighs with edematous light purplish-red patches. Especially when dermatomyositis is found above the age of 40, about half of the patients have cancer associated with them, with lung cancer being common. Therefore, when dermatomyositis, scleroderma or acanthosis nigricans suddenly occurs above middle age, it should be carefully examined for the presence of occult lung cancer. Therefore, do not wait until you have a violent cough to think of the possibility of lung cancer and go to the hospital for examination. People aged 40 years or above should preferably have a chest X-ray once a year. If the clinical presentation resembles lung cancer but the chest X-ray is normal, CT examination should be performed again because CT is more sensitive than chest X-ray in detecting lung cancer. The results of sputum exfoliative cell examination should also be referred to in order to make a clear diagnosis.