Most cancer patients receive radiation treatments every day, five days a week (Monday through Friday) for five to eight weeks. This allows doctors to receive enough radiation in the body to kill cancer while allowing healthy cells time each day to recover. During external beam radiation therapy, a beam of radiation is directed through the skin to the cancer and the immediate surrounding area to destroy the main tumor and any nearby cancer cells. To minimize side effects, treatments are usually given five days a week, Monday through Friday, for several weeks.
If the goal of treatment is palliative (to control symptoms), treatment will last two to three weeks. Using many small doses (fractions) for daily radiation, rather than a few large doses, helps protect healthy cells in the treatment area. Stopping treatment on weekends allows normal cells to recover. Other targeted therapies act more directly on cancer cells by blocking the action of molecules on the surface of cancer cells called growth factors. The number of radiation treatments you will need depends on the size, location and type of cancer you have, the intention of treatment, your general health, and other medical treatments you may receive.
For example, some medications work to prevent the growth of cancers by preventing the formation of new blood vessels that would feed the cancer. Brachytherapy is used when the doctor decides that the best way to treat cancer is to deliver a higher dose of radiation into the body. You may have different side effects depending on the type of cancer you have and where in your body radiation therapy is given. Radiation therapy after mastectomy may be recommended to kill any cancer cells left after surgery. Free radicals in the environment can damage all cells, but in the case of radiation therapy, they focus on cancer cells. The radiation oncologist will work with your family doctor and other cancer specialists, such as surgeons and medical oncologists, to oversee your care. Again, the exact duration of radiation therapy depends significantly on the characteristics of the cancer.
Instead of using an external radiation machine, the radioactive material is sealed in a thin wire or catheter (hollow tube) and implanted directly into the cancerous area. The time between daily treatments allows healthy cells to repair much of the radiation effect, while cancer cells are not as likely to survive the changes. It is important to note that advances in radiation technology and delivery allow healthcare providers to deliver more radiation to focused areas, based on the individual characteristics of the patient and tumor.