Understanding Radiation Therapy

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Long-term side effects of radiation therapy

During and right after radiation therapy, it can be hard to think ahead to what might happen many years in the future. But depending on the type of treatment and the location of the cancer, there may be long-term side effects from your radiation treatment. (Some of these are described in more detail in the section below, called “Managing side effects of treatment to certain parts of the body.”) Talk to your doctor about possible long-term problems from the treatment you’re getting. Even though they are less common than short-term ones, these problems should still be taken into account when making decisions about radiation therapy.

Damage to your body

Radiation can damage normal cells, and sometimes this damage can have long-term effects. For instance, radiation to the chest area may damage the lungs or heart. In some people this might affect a person’s ability to do things. Radiation to the abdomen (belly) or pelvis can lead to bladder, bowel, fertility, or sexual problems in some people. Radiation in certain areas can also lead to fluid build-up and swelling in parts of the body, a problem called lymphedema (lim-fuh-DEE-muh).

See the “To learn more” section to find out where you can get more detailed information on many of these long-term side effects.

Risk of another cancer

A long-term problem linked to radiation treatment is the possible increased risk of getting a second cancer some time in the future. A second cancer may develop many years later, and is caused by the radiation damage to healthy tissues. The risk of this happening is small but real.

The link between radiation and cancer was noted many years ago in studies of atomic bomb survivors, workers exposed to radiation on their jobs, and patients treated with radiation therapy. For instance, young women who had whole-body radiation for the treatment of Hodgkin disease were found to be at increased risk for breast cancer and other cancers later in life. (Whole-body radiation is seldom used for Hodgkin disease today.) Some cases of leukemia are also linked to past radiation exposure. The leukemia usually develops within a few years of exposure – risk peaks about 5 to 9 years after the radiation exposure and then slowly declines. Other types of cancer after radiation exposure often take much longer to develop. Most do not happen until at least 10 years after exposure, and some are diagnosed 15 or more years later.

You can learn more about this in Second Cancers Caused by Cancer Treatment, which can be read online or sent to you.

What does this mean to me?

Radiation therapy has steadily improved over the past few decades. Treatments now target the cancers more precisely, and more is known about choosing the best radiation doses. More precise radiation means less damage to nearby healthy tissues. This often means fewer side effects. These advances may also reduce the number of second cancers that result from radiation treatment, but this is not yet known. Still, the overall risk of second cancers is low and must be weighed against the benefits of radiation treatments.

Talk to your doctor before you start radiation to make sure you are aware of the possible long-term effects. This can help you make an informed treatment decision and help you know what symptoms you may need to watch out for after treatment.

Last Medical Review: 05/02/2014
Last Revised: 05/02/2014