Radiation Therapy What is Radiation Therapy? Radiation therapy uses high-energy X-rays to kill cancer cells and shrink tumours. It is a type of cancer treatment that deals with many types of cancer as well as some conditions that are non-cancerous. It can also be used alone or combined with other treatments such as surgery or chemotherapy. How do I access Radiation Therapy? If you are concerned about your health, please talk with your family physician or primary health care provider. You may then be referred to us for testing and follow-up treatment if needed. To learn more about Horizon’s Cancer Care (Oncology) services, and/or to prepare for an appointment, click here.