Radiation therapy is among the oldest and most economical ways to treat cancer. In radiation therapy (also called radiotherapy), high-energy rays are used to damage cancer cells and stop them from growing and dividing. Like surgery, radiation therapy is a local treatment; it can affect cancer cells only in the treated area.
Radiation therapy can be administered to accomplish a wide variety of goals, and can be used at many stages of cancer treatment. In an early stage of cancer, radiation can be used to control or even cure the disease. It can be used in conjunction with surgery to either shrink a tumor before an operation, or to prevent an excised tumor from growing back. It can also be used in cooperation with chemotherapy to aid in shrinking or reducing cancerous spread.
There are two main types of radiation therapy: external radiation therapy and internal radiation therapy. External radiation is delivered in high energy rays from a machine outside the body. Its goal is to be as least invasive as possible. The goal of internal radiation therapy is to get as close to the affected area as possible. It may come from an implant (a small container of radioactive material) placed directly into or near the tumor. Some patients get both kinds of radiation therapy.
External radiation therapy is usually given on an outpatient basis in a hospital or clinic 5 days a week for several weeks. Patients are not radioactive during or after the treatment. For internal radiation therapy, the patient stays in the hospital for a few days. The implant may be temporary or permanent. Because the level of radiation is highest during the hospital stay, patients may not be able to have visitors or may have visitors only for a short time. Once an implant is removed, there is no radioactivity in the body. The amount of radiation in a permanent implant goes down to a safe level before the patient leaves the hospital. Many medical staff are involved in giving radiation therapy; a medical team may include a radiation oncologist, radiation physicist, dosimetrist, radiation therapist, or radiation therapy nurse.
With radiation therapy, the side effects depend on the treatment dose and the part of the body that is treated. The most common side effects are tiredness, skin reactions (such as a rash or redness) in the treated area, and loss of appetite. Radiation therapy also may cause a decrease in the number of white blood cells, cells that help protect the body against infection. Although the side effects of radiation therapy can be unpleasant, the doctor can usually treat or control them. It also helps to know that, in most cases, they are not permanent.