Radiation therapy is a local treatment as opposed to chemotherapy that is a systemic treatment. That is, radiation treats only the area at which it is directed. High levels of radiation can kill cells or keep them from growing and dividing. Radiation therapy is a useful tool for treating cancer because cancer cells are growing and dividing more rapidly than many of the normal cells around them. In addition, most normal cells appear to recover more fully from radiation effects than cancer cells.
Doctors carefully monitor the intensity of treatments and the amount of normal tissue being treated.
Radiation therapy is an effective way to treat many kinds of cancer in almost any part of the body. Half of all people with cancer are treated with radiation, and the number of cancer patients who have been cured is rising every day. For many patients, radiation is the only kind of treatment needed. Thousands of people are free of cancer after having radiation treatments alone or in combination with surgery, chemotherapy, and immunotherapy. After surgery, radiation therapy is frequently used to stop the growth of any cancer cells that remain.