Knee pain is usually not a phenomenon of early stage of lung cancer. Most patients with lung cancer have no obvious symptoms in the early stage, but patients’ conditions are different and cannot be generalized. The cause of lung cancer is not yet clear, it may be caused by smoking, air pollution, ionizing radiation, diet, heredity and other factors. Lung cancer can have no obvious symptoms in early stage, and knee pain is not an early symptom of lung cancer. With the development of the disease, when lung tumor invades into adjacent organs and tissues, patients may have cough, paroxysmal dry cough, chest pain, which may be aggravated when coughing. Some patients may also have symptoms such as blood in sputum, hemoptysis and dyspnea. And there are many causes of knee pain, may be overwork, strenuous exercise and other physiological factors, or consider the osteochondritis, trauma, osteomyelitis, gout and other diseases. It is recommended that patients with knee pain go to a regular hospital and undergo a relevant examination to determine the cause of the problem. Once the diagnosis is confirmed, you need to take relevant treatment measures under the guidance of the doctor to avoid delaying the condition.