Radiation Therapy
Educational information. Individual clinical review of this presentation by Dr. Ehsan is not yet documented. It does not replace personal medical evaluation.
Source: MedlinePlus, National Library of Medicine. Read the original source
MedlinePlus data edition September 26, 2026. Imported September 27, 2026. These dates do not indicate a new clinical review of the article.
What is radiation therapy?
Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from spreading. It may also be used for easing cancer symptoms. Radiation therapy may damage healthy cells. They can usually repair themselves more easily than cancer cells.
You may need days or weeks of treatment before the radiation starts killing cancer cells. But cancer cells should keep dying for weeks or months after your treatment ends.
When is radiation therapy used for cancer treatment?
Radiation therapy treats many types of cancer. It may be used at different times or for different reasons during your treatment. Sometimes radiation is used with other treatments, like surgery, chemotherapy, or immunotherapy.
How is radiation therapy given?
You may get radiation therapy once a day or in smaller doses twice a day for a few weeks. The radiation may be external, from special machines, or internal from radioactive substances placed inside your body.
The type of radiation therapy you get depends on many factors, including:
- The type of cancer
- The size of the cancer
- Where the cancer is in your body
- How close the cancer is to normal tissues that are sensitive to radiation
- How far the radiation needs to travel into your body
- Your general health and medical history
- Whether you will have other types of cancer treatment
- Other factors, such as your age and other medical conditions
What are the side effects of radiation therapy?
Your treatment must be carefully planned to reduce side effects. Radiation therapy can damage normal cells as well as cancer cells. Healthy cells usually repair themselves but damaging them can cause side effects.
Side effects can vary from person to person. Common side effects include skin changes and fatigue. Other side effects depend on the part of your body being treated. Most side effects go away a few months after you are done with treatment.
NIH: National Cancer Institute
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