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Home Your Health Multimedia Encyclopedia Radiation therapy

Radiation therapy

Definition

Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells.

Alternative Names

Therapy - radiation; Radiotherapy

Information

Cancer cells multiply faster than normal cells in the body. Because radiation is most harmful to rapidly growing cells, radiation therapy damages cancer cells more than normal cells. Specifically, radiation therapy damages the DNA of cancer cells. Doing so prevents the cancer cells from growing and dividing. Unfortunately, certain healthy cells can also be killed by this process. The death of healthy cells can lead to side effects.

Radiation therapy is used to fight many types of cancer. It is often used to shrink a tumor as much as possible before surgery. Radiation can also be given after surgery to prevent the cancer from coming back.

For certain types of cancer, radiation is the only treatment needed. Radiation treatment may also be used to provide temporary relief of symptoms, or to treat cancers that cannot be removed with surgery.

There are two forms of radiation therapy:

• External beam radiation is the most common form. This method carefully aims high powered x-rays or particles directly at the tumor from outside of the body.
• Internal beam radiation uses radioactive seeds that are placed directly into or near the tumor. Internal beam radiation is also called interstitial radiation or brachytherapy.

The following are some commonly used radioactive substances:

• Cesium (137Cs)
• Cobalt (60Co)
• Iodine (131I)
• Phosphorus (32P)
• Gold (198Au)
• Iridium (192Ir)
• Yttrium (90Y)
• Palladium (103Pd)

Radiation therapy can have many side effects. These side effects depend on the part of the body receiving radiation, the dose of radiation, and how often you have the therapy.

• Hair loss
• Skin pain
• Red, burning skin
• Shedding of the outer layer of skin (desquamation)
• Increased skin coloring (hyperpigmentation)
• Thinning of skin tissue (atrophy)
• Itching
• Fatigue and malaise
• Low blood counts
• Difficulty or painful swallowing
• Edema (swelling of skin and soft tissues)
• Changes in taste
• Loss of appetite
• Nausea
• Vomiting
• Increased susceptibility to infection

Radiation therapy can be harmful to a developing baby in the womb during pregnancy.

References

Perry MC. Principles of cancer therapy. In Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 192.