Radiation Therapy for Cancer: How It Works and What to Expect

Radiation therapy is a cancer treatment that uses high doses of radiation to kill cancer cells and stop them spreading. It can also ease cancer symptoms. It may damage healthy cells too, but they can usually repair themselves more easily than cancer cells.

It can take days or weeks of treatment before the radiation starts killing cancer cells, and they should keep dying for weeks or months after treatment ends.

When it is used

Radiation treats many kinds of cancer, at different points and for different reasons during treatment, sometimes together with surgery, chemotherapy or immunotherapy.

How it is given

It may be given once a day, or in smaller doses twice a day, for a few weeks. It can be external, from special machines, or internal, from radioactive substances placed inside the body. The type depends on:

• the type and size of the cancer, and where it is;
• how close it is to normal tissue that is sensitive to radiation;
• how far the radiation must travel into the body;
• your general health and medical history;
• whether you will have other cancer treatments;
• other factors, such as age and other medical conditions.

Side effects

Treatment is carefully planned to limit side effects. Radiation can damage normal cells as well as cancer cells; healthy cells usually repair themselves, but the damage can cause side effects, which vary from person to person. The most common are skin changes and fatigue; others depend on the part of the body treated. Most go away within a few months of finishing treatment.

Sources

• MedlinePlus, U.S. National Library of Medicine, "Radiation Therapy," from the NIH National Cancer Institute. https://medlineplus.gov/radiationtherapy.html
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