The first sign of lung cancer is not knee pain. Most of lung cancer patients’ early symptoms are not obvious. Cough is the most common symptom of lung cancer patients, and cough as the first symptom accounts for 35% to 75%. Blood in sputum or hemoptysis and chest pain are also common symptoms of lung cancer. Chest pain is also a common symptom of lung cancer. A small number of patients may have chest tightness and shortness of breath as the first symptom. In advanced lung cancer patients, if bone metastasis occurs, patients may show knee pain. Severe emaciation, anemia, cachexia and other manifestations may also occur in advanced lung cancer. In addition, for the phenomenon of knee pain, patients should be alerted to bone and joint diseases, such as bone fracture, bone cancer, rheumatoid arthritis and so on. If the patient is not feeling well, it is recommended to go to regular hospitals for clear diagnosis and receive standardized treatment under the guidance of doctors.