1.Lymph node metastasis The most common are mediastinal lymph nodes and supraclavicular lymph nodes, mostly on the same side of the lesion, and a few can be on the opposite side, mostly harder, single or multiple nodes, which can sometimes be the first complaint for consultation. Enlargement of paratracheal or subglottic lymph nodes may compress the airway and present with chest tightness. Shortness of breath or even choking. Dysphagia may occur when the esophagus is compressed. Pleural invasion and metastasis Pleura is a common invasion and metastasis site of lung cancer, including direct invasion and implantation metastasis. Clinical manifestations vary according to the presence or absence of pleural effusion and the amount of pleural fluid. Besides direct invasion and metastasis, the causes of pleural fluid also include obstruction of lymph nodes as well as accompanying obstructive pneumonia and pulmonary atelectasis. Superior vena cava syndrome: direct tumor invasion or mediastinal lymph node metastasis compresses the superior vena cava, or the embolism in the cavity causes its narrowing or occlusion, resulting in obstruction of blood reflux, and a series of symptoms and signs appear, such as headache, swelling of face and face, cervico-thoracic varicose veins, increased pressure, difficulty in breathing, coughing, chest pain, and difficulty in swallowing, and often fainting or vertigo when bending down, and so on. Anterior chest and epigastric veins may be compensatory varicose, reflecting the time of superior vena cava obstruction and the anatomical location of the obstruction. Kidney metastasis About 35% of patients who die of lung cancer are found to have kidney metastasis, which is also the most common metastatic site of patients who die within 1 month after surgical resection of lung cancer. Most of the kidney metastases have no clinical symptoms, but sometimes can be manifested as low back pain and renal insufficiency. Liver metastasis can be manifested as loss of appetite, pain in liver area, sometimes accompanied by nausea, serum γ-GT is often positive, AKP is progressively increased, and liver enlargement, hardness and nodularity can be found during physical examination. Small cell lung cancer is good for pancreatic metastasis, and may present with pancreatitis symptoms or obstructive jaundice. Various cell types of lung cancer can metastasize to liver, gastrointestinal tract, adrenal glands and retroperitoneal lymph nodes, which are mostly asymptomatic clinically and often found during physical examination. Bone metastasis The common sites of bone metastasis of lung cancer include ribs, vertebrae, iliac bone and femur, etc. However, ipsilateral ribs and vertebrae are more common, which are manifested as localized pain and localized pressure and percussion pain. Crestal metastases may compress the spinal canal leading to obstruction or compression symptoms. Joint involvement may result in joint effusion, and cancer cells may be detected by puncture. (1) Brain, meningeal and crural metastases: The incidence is about 10%, and the symptoms may vary according to the site of metastasis. Common symptoms are increased intracranial pressure, such as headache, nausea, vomiting and change of mental status, etc. Rare symptoms include seizure, cerebral nerve involvement, hemiparesis, ataxia, aphasia and sudden fainting, etc. Meningeal metastasis is not as common as cerebral metastasis. Meningeal metastasis is not as common as brain metastasis, which often occurs in patients with small cell lung cancer, and its symptoms are similar to brain metastasis. (2) Encephalopathy and cerebellar cortical degeneration Encephalopathy mainly manifests as dementia, psychosis and organic lesions, while cerebellar cortical degeneration manifests as acute or subacute limb dysfunction, difficulty in movement of limbs, tremor of movements, difficulty in pronouncing words, vertigo and so on. There are reports that the above symptoms can be relieved after tumor resection. Heart invasion and metastasis It is not uncommon for lung cancer to involve the heart, especially in central lung cancer. Tumor may invade the heart through direct spread, or it may spread retrogradely through lymphatic vessels, blocking the draining lymphatic vessels of the heart and causing pericardial effusion. Those with slower development may be asymptomatic or only have pain in anterior region of the heart, under the arch of the ribs or in the upper abdomen. Those with faster development may present typical symptoms of pericardial tamponade, such as cardiac tachycardia, palpitation, jugular facial veins, enlarged cardiac border, low and distant heart sounds, hepatomegaly, ascites and so on. Peripheral nervous system symptoms: (1) Compression or invasion of cervical sympathetic nerve by carcinoma may cause Horner’s syndrome, which is characterized by narrowing of pupil on the diseased side, drooping of upper eyelid, sunken eyeballs and lack of sweat on the face and face. (2) Compression or invasion of brachial plexus nerve caused brachial plexus nerve compression sign, which was characterized by burning-like radiating pain in the ipsilateral upper limb, local sensory abnormality and trophic atrophy. (3) When the tumor violates the phrenic nerve, it may favor diaphragmatic paralysis, chest tightness, shortness of breath, and contradictory movement of diaphragm under X-ray fluoroscopy. (4) When the tumor compresses or violates the recurrent laryngeal nerve, it may cause paralysis of the vocal cords and hoarseness. (5) Lung apical tumor (suprapulmonary sulcus tumor) invades cervical 8 and thoracic 1 nerves, brachial plexus nerves, sympathetic ganglion, and adjacent ribs, causing severe shoulder and arm pain, sensory abnormality, paraplegia or weakness of one side of the arm, and muscle atrophy.