1.What is radiation therapy? The application of radiation to treat malignant tumors is often referred to as radiation therapy for cancer. Radiation therapy is divided into distant therapy and brachytherapy according to the distance between the radiation therapy source and the patient’s body. In recent years, radiation therapy is used for both malignant tumor treatment and benign disease treatment. 2.Why can radiation treat cancer? The most important feature of radiation is that it is particularly penetrating. In addition, radiation can damage DNA, the genetic material in cells, thus causing cell injury and death. This injury has different effects on cells. The greatest damage is done to cancer cells, which multiply quickly. The normal cells of the human body can often return to normal after irradiation with the help of their powerful repairing effect. According to the different effects of radiation on cancer cells and normal cells, radiotherapists can use radiation as an “invisible scalpel” to destroy cancer cells. The common malignant tumors that belong to radiotherapy are: Intracranial tumors: malignant glioma, medulloblastoma, pineal tumor, craniopharyngioma and germ cell tumor Head and neck tumors: nasopharyngeal cancer, maxillary sinus cancer, retinoblastoma, oral cancer, tongue cancer, tonsil cancer, thyroid cancer, laryngeal cancer and lymph node metastasis in the neck Thoracic tumors: lung cancer, esophageal cancer, malignant thoracic adenoma and breast cancer Abdominal tumors: pancreatic cancer, rectal cancer, kidney cancer, bladder cancer, prostate cancer Hematopoietic system: leukemia Lymphatic system: malignant lymphoma Reproductive system: seminoma, penile cancer, cervical cancer, uterine corpus cancer, vulvar cancer Skin: skin cancer, malignant melanoma Extremities: soft tissue sarcoma Skeletal system: osteosarcoma, bone metastatic tumor 4.Which patients should not receive radiotherapy? Only when the tumor has been widely spread, the patient’s general condition is very poor and cannot tolerate radiotherapy, or when it is accompanied by organ perforation and serious lack of white blood cells and platelets in the blood is not suitable for radiotherapy. 5.Does radiation therapy damage normal tissues? Radiation will damage normal tissues and maximize the killing of tumors while protecting normal tissues. Because when treating various tumors, radiation will inevitably irradiate the normal tissues or organs around the tumor, which will cause certain damage to these tissues and organs. This damage is divided into two cases, one kind of damage appears when the radiation reaction does not exceed the tolerated amount of the tissue or organ. For example, the skin becomes thin and flower magic-like after radiotherapy. Such damage does not affect the patient’s function much and is not life-threatening. However, in some cases, some damage must be caused in order to control the tumor, if the tumor is located in a shallow area or in an unimportant organ that does not affect the patient’s function. Such damage can also be allowed. At present, great achievements have been made in protecting normal tissues, and many advanced techniques that are indeed effective have been developed. 6.Why is radiation therapy done 5 times a week? This is a schedule of external radiotherapy that people have worked out in the clinical practice of radiotherapy. This kind of radiotherapy is usually done 5 times a week for several weeks, and the total amount of radiotherapy is divided into multiple groups, which can make the normal tissue cells have a chance to repair during the weekend rest, but the tumor tissues with heavy damage and poor repair cannot be fully repaired, which helps to protect the healthy body tissues. If radiotherapy is done every day, normal tissues will not get rest and cannot be fully repaired, thus it is not good for health, therefore, radiotherapy cannot be done every day. 7.How long is a course of radiation therapy? The length of a course of radiotherapy is based on the pathological type of the tumor, the early and late stage of the disease and the systemic condition, etc. The goal of radiotherapy is radical, palliative or adjuvant. Radical radiotherapy, according to the conventional radiotherapy protocol, irradiates 5 times a week with a weekly dose of 800 – 1000 CGY, and the irradiation dose is generally 6000 – 7000 CGY, then it will take 6 – 8 weeks to complete this course of treatment. Palliative radiotherapy is a form of symptom reduction treatment, usually using high dose fractionated short-term shock therapy.