Toxic side effects occurring within 90 days after the start of radiotherapy for lung cancer are acute radiation damage, which is often self-limiting in nature. Late radiation damage mostly occurs 6 to 18 months after the end of radiotherapy, and is mostly irreversible tissue damage. 1.The incidence of acute radiation lung injury in lung cancer radiotherapy is 33%, and 82% of late radiation injury is fibrosis of lung. Acute radiation lung injury and chronic pulmonary fibrosis occur due to large radiation fields, high doses and rapid irradiation in the lung. The treatment of acute radiation lung injury is mainly rest, the use of adrenocorticotropic hormones and bronchodilator drugs, if necessary, oxygen. If there is secondary lung infection, antibiotics must be used at the same time. There is no special treatment for mild chronic pulmonary fibrosis, and symptomatic treatment is usually given. Radiation lung injury is a complication of lung cancer radiation therapy that cannot be easily controlled. The key lies in prevention, and irradiation dose, irradiation method and correct design of irradiation field should be carefully and carefully planned according to individual characteristics. 2. The occurrence of radiation esophagitis increases with the increase of dose. Radiation esophagitis is more common. Painful eating at doses of 10-20Gy is mainly a reaction of the esophageal mucosa, while pain at 30-40Gy may be a reaction of the esophageal muscle layer and the tissues surrounding the esophagus. If the pain symptom is mild, it can be left untreated and can be relieved by itself with continued radiation; if the pain is severe, mucosal surface anesthetics such as 1% procaine solution can be used orally, and antibiotics can also be used; if the pain is severe, radiotherapy should be suspended. Later esophageal injury is less common, but there are reports of esophageal strictures, adhesions, ulcers and fistula formation in the literature, mostly when the total dose received by the esophagus is >70Gy. 3.The incidence of cardiac injury caused by radiation therapy increases with the increase of radiation therapy dose. When the irradiated volume of heart exceeds 60% and the dose is >40Gy, comorbidities such as pericarditis, pericardial effusion, myocarditis and fibrosis occur in about 5% of patients, and the incidence is 50% when the dose is above 60Gy. The acute radiological heart damage produced during lung cancer radiotherapy is often subclinical, and ECG abnormalities can be found, with ST-T changes being the most common, followed by atrial premature, ventricular premature, atrial fibrillation, sinus tachycardia, and sinus bradycardia. Atrioventricular block and abnormal Q waves are rare. All previous ECG abnormalities can be aggravated after radiotherapy. In the elderly, cardiac changes are more frequent than in the young. For those who have insufficient myocardial blood supply or atherosclerosis, the amount of cardiac (mainly left ventricular) irradiation should be reduced. 4.Radiation myelitis The main symptom in the early stage is electric shock-like numbness in the limbs, especially when the patient lowers his head. The condition can be controlled and recovered with the application of large amounts of vitamins and nerve cell-nourishing drugs, as well as adrenal corticosteroids. The late stage is mainly transverse spinal cord injury, manifested as transverse paraplegia, which occurs more than 1 year after radiotherapy. As long as the radiation dose to the spinal cord is controlled within the safe range of less than 50Gy, 25 times and 5 weeks, this complication will not occur. As the number of lung cancer patients in China continues to increase, lung cancer treatment and prevention should not be underestimated. The above is a brief introduction to the types of lung cancer. For those who are related to the causative factors of lung cancer, it is recommended to take preventive measures for lung cancer and then do specific treatment according to the doctor’s instructions, hoping that patients can recover soon!