The most obvious signs of lung metastasis in kidney cancer patients are back pain and chest pain, coughing up sputum and hemoptysis, chest tightness and shortness of breath and pleural effusion. 1. Lower back pain and chest pain: This is the result of metastasis of kidney cancer cells to the lungs, which leads to the destruction of lung tissues and causes pain in lower back and chest, and the degree of pain gets worse with the progress of cancer cells. 2. Coughing, coughing, sputum, hemoptysis and chest tightness and shortness of breath: this is also related to the metastasis of cancer cells to lung tissues, the cancer cells destroy the trachea or lung tissues and then cause bleeding, which reflexively causes the patient to cough, and at the same time, due to the destruction of lung tissues, the patient can not effectively ventilate and exchange air, which results in chest tightness and shortness of breath. 3. Pleural effusion: patients with metastatic lung cancer may cause pleural effusion, which can be clarified by chest CT examination. If kidney cancer combined with lung metastasis is diagnosed or suspected, patients should go to hospital as soon as possible for active treatment. Doctors should formulate individualized diagnosis and treatment plan according to specific conditions to avoid delay.