Early symptoms of lung cancer include irritating dry cough, coughing up blood, hoarseness, dyspnea, etc. Some of them may have pain radiating to the chest and back, especially at night, which is obvious, and the disease will gradually develop into emaciation, fatigue and dyspnea. Knee joint pain is not an early symptom of lung cancer, the causes of knee joint pain include osteophytes, synovitis, rheumatoid arthritis, gout, calcium deficiency, etc. In serious cases, knee joints will be swollen and activities will be limited. If bone metastasis of lung cancer occurs, bone destruction of knee joint may occur, which can be further diagnosed by CT examination. Therefore, knee joint pain is not an early symptom of lung cancer, and if there are respiratory symptoms, it is necessary to go to hospital for radiography.