What are the indications and contraindications of radiation therapy? According to different kinds of tumors in each system, the indications for current treatment can be divided into the following categories: (1) Digestive system Early surgery and radiation therapy for oral cancer are equally effective, and some parts are more suitable for radiation therapy, such as tongue root cancer and tonsil cancer. Comprehensive treatment in the middle stage is better with radiation therapy before surgery. Late stage can be treated with palliative radiation therapy. Surgery is the main treatment for esophageal cancer in early stage, and radiation therapy is the main treatment for middle and late stage. Liver, pancreas, stomach, small intestine, colon and rectum cancer are mainly treated by surgery. Colon and rectal cancer surgical glue radiation may be beneficial. The efficacy of intracavitary radiation for early rectal cancer is the same as that of surgical treatment. Radiotherapy for liver and pancreatic cancer has a certain palliative effect. (2) Respiratory system Nasopharyngeal cancer is mainly treated with radiotherapy. Maxillary sinus cancer is better treated with radiotherapy before surgery. For those who cannot be operated, radiotherapy alone can cure part of them. Laryngeal cancer is treated by radiotherapy or surgery in the early stage, and radiotherapy and surgery are combined in the middle and late stage. Lung cancer is mainly treated by surgery, but those who are not suitable for surgery and do not have distant metastasis can be treated by radiotherapy, and a few of them can be cured. Small cell end-differentiated lung cancer should be treated with radiotherapy plus chemotherapy. (3) Genitourinary system Renal clear cell carcinoma is mainly operated, and radiotherapy after surgery has certain benefits. In early stage of bladder, surgery is the main treatment, and radiotherapy before surgery in middle stage has certain benefits, and palliative treatment can be done in late stage. Renoblastoma is better treated with a combination of surgery, surgery hand radiotherapy and chemotherapy. Testicular tumor should be operated first, and then post-surgical radiotherapy. Cervical cancer has the same effect of surgery and radiotherapy in early stage, and above stage II can only have better effect of radiotherapy alone. Uterine body cancer should be treated with radiotherapy before surgery, and those who cannot be operated can also be treated with radiotherapy. (4) Breast cancer is mainly treated by surgery. Any stage I or II breast cancer with tumor located in the outer quadrant and negative axillary lymph nodes will not be treated by radiotherapy after surgery, while stage I and tumor located in the inner quadrant or stage II breast cancer will be treated by radiotherapy after surgery. Stage III irradiation before surgery is also beneficial. In recent years, some foreign countries have adopted radiotherapy for breast lymphatic area after surgery to remove tumor in early stage breast cancer, which is also very effective. (5) Neurological tumors Most brain tumors should be treated with radiotherapy after surgery. For medulloblastoma, radiotherapy should be the main treatment. Neuroblastoma should be treated with radiotherapy or chemotherapy after surgery. Pituitary tumors can be treated with radiotherapy or post-surgery radiotherapy. (6) Skin and soft tissue malignant tumors Skin mucosa (including penis and lip) can be treated with surgery or radiotherapy in early stage, and melanoma and other sarcomas can also be treated with radiotherapy in late stage, which should be mainly operated. It can also be considered with radiotherapy. (7) Bone malignant tumors Bone sarcoma is mainly surgery, but also can be radiotherapy before surgery. Osteosarcoma and Ewing’s tumor can be treated with radiotherapy supplemented by chemotherapy. (8) Lymphatic tumors Stage I and II are mainly treated with radiotherapy, and Stage III and IV are mainly treated with chemotherapy, and local radiotherapy can be added. So what conditions should be regarded as contraindications to radiotherapy? There are few absolute contraindications to radiotherapy, especially low palliative treatment, such as pain relief of local metastases is mostly effective. However, it also depends on the conditions of patients and units to decide. Generally speaking, advanced tumor patients in cachexia can be made as absolute contraindications to radiation, in addition, esophageal cancer perforation and lung cancer combined with large amount of cavity effusion should also be listed as absolute contraindications. Tumors that are not sensitive to radiation should be considered as relative contraindications, such as melanoma of the skin, gastric cancer, small intestine cancer, soft tissue sarcoma, chondrosarcoma of bone, etc. Moderately radiosensitive tumors, such as lymphatic tumors, can be treated with radiotherapy again. Acute inflammation and heart failure should be controlled before radiotherapy. If lung cancer requires large area irradiation and the lung function is seriously incompetent, radiotherapy should not be given.