Esophageal cancer is a malignant tumor occurring in the epithelial tissue of the esophagus, and China is a high incidence area for esophageal cancer, with nearly 150,000 people dying from this disease every year nationwide. Although the effect of chemotherapy alone is not ideal, chemotherapy is often used as adjuvant treatment. Patients with esophageal cancer can also die from complications, and the following are the complications of esophageal cancer. 1. Water and electrolyte disorders: due to dysphagia, such patients have the tendency to have severe hypokalemia and muscle weakness. Normal people secrete about 1~2 liters of saliva every day, inorganic substances of which include sodium, potassium, calcium and chloride. The concentration of potassium in saliva is higher than that in any other gastrointestinal secretions, usually 20 mmol/ml. Therefore, patients with esophageal cancer can develop significant hypokalemia when they cannot swallow saliva due to dysphagia. Some squamous cell carcinomas can produce parathyroid hormone and cause hypercalcemia, even if the patient has no bone metastases. Hypercalcemia in esophageal cancer patients without bone metastasis before surgery is often a sign indicating poor prognosis. 2.Esophageal perforation: Advanced esophageal cancer, especially ulcerated esophageal cancer, causes perforation due to local erosion and severe ulceration of tumor. Different symptoms may appear depending on the perforation site and adjacent organs. Perforation of trachea causes esophagotracheal fistula, which leads to choking and coughing anatomy when eating and drinking, especially when eating liquid diet; perforation of mediastinum can cause mediastinitis, which leads to chest tightness, chest pain, cough, fever, accelerated heart rate and elevated white blood cells; perforation of lung causes pulmonary abscess, which leads to high fever, cough and pus sputum; perforation of aorta causes esophagoaortic fistula, which can lead to hemorrhage and death. 3. Cachexia: In advanced cases, the increasing difficulty in swallowing, resulting in long-term starvation leading to negative nitrogen balance and weight loss, has a direct impact on the incidence of complications and surgical mortality after esophagectomy. Virtually every patient with advanced esophageal cancer with obstructive symptoms has varying degrees of dehydration and reduction in total body fluid due to their difficulty in eating through the mouth. Patients show cachexia and obvious water loss, which is manifested as high emaciation, weakness, loose and dry skin, and a state of exhaustion. 4.Aspiration pneumonia: Due to aspiration and aspiration pneumonia caused by esophageal obstruction, patients may have fever and systemic toxic symptoms. 5.Organ metastasis: If there is metastasis of important organs such as lung, liver and brain, respiratory distress, jaundice, ascites, coma and other symptoms specific to the corresponding organs may appear. Patients with esophageal cancer who have esophage-tracheal fistula, metastasis of supraclavicular lymph nodes and other organs, laryngeal regurgitant nerve paralysis and cachexia are all advanced esophageal cancer. 6.Cancer metastasis can cause vocal cord paralysis and hoarseness, shortness of breath and irritating dry cough caused by tumor compression and invasion of trachea and bronchus, diaphragm paralysis caused by invasion of phrenic nerve, accelerated heart rate caused by invasion of vagus nerve, arm pain and abnormal sensation caused by invasion of brachial plexus nerve, superior vena cava compression syndrome caused by compression of superior vena cava, liver, lung, brain and other important organs. Cancer metastasis of liver, lung, brain and other important organs can cause jaundice, ascites, liver failure, respiratory distress, coma and other complications. 7.Bleeding or vomiting blood: some patients with esophageal cancer have vomiting, some patients with esophageal cancer have vomiting blood due to tumor invasion of large blood vessels, and occasionally there is haemorrhage. 8.Sympathetic ganglion compression: if the cancer compresses sympathetic ganglion, sympathetic nerve paralysis (Homer syndrome) will occur. According to the literature, some patients with esophageal squamous cell carcinoma have hypertrophic osteoarthropathy, some patients with occult esophageal carcinoma have dermatomyositis, and some patients with esophageal obstruction have “swallowing syncope”, which may be a vagus-mediated reaction.