In the early stage, the symptoms of rectal cancer metastasis to lung are not so obvious, mainly mild coughing, and with the gradual development of the disease, patients will cough more than once, and even hemoptysis and blood in sputum will occur. At a certain period of time, patients will also experience chest pain in the lungs, which is mainly caused by the irritation of the pleura by the metastatic lesions. In case of lymph node metastasis, the lymph nodes on the clavicle may be enlarged. When liver metastases invade the pleura, main bronchus or adjacent structures, symptoms of lung metastases may appear similar to those of lung cancer, such as cough, hemoptysis, chest pain, chest tightness and shortness of breath. If mediastinal metastases are also present, patients may experience hoarseness, choking cough, facial edema, diaphragmatic paralysis, compression of the esophagus or trachea, and occasionally acute pulmonary embolism, which may manifest as progressive and gradually increasing dyspnea.