Radiation Treatment for Cancer

Discusses radiation therapy, including external, internal, and systemic forms. Covers how it works. Also covers risks of radiation and side effects that may occur right away or later.

Radiation Treatment for Cancer

Treatment Overview

Radiation therapy uses high energy rays, such as X-rays, to destroy cancer cells and shrink tumors in different parts of the body. It is used to treat many types of cancer.

Radiation damages the genetic material of cancer cells, which stops their growth. Radiation may also damage normal cells that are close to the cancer cells. But normal cells usually repair themselves, while the cancer cells cannot.

Side effects from radiation therapy are a problem. Usually the side effects are temporary. But some side effects may be permanent. Researchers keep looking for the lowest radiation dose that effectively kills cancer cells. And with new technology, people getting radiation therapy have fewer problems than in the past.

Radiation therapy may be given in these ways:

  • External beam radiation therapy (EBRT). Radiation comes from a machine outside the body and is aimed at a specific part of your body. It is usually given in multiple doses over several weeks. The two most common forms of external radiation are:
    • Conformal radiotherapy (3D-CRT): 3D-CRT uses a three-dimensional planning system to target a strong dose of radiation to where the cancer cells are in the body. This helps to protect healthy tissue.
    • Intensity-modulated radiation therapy (IMRT): IMRT uses newer 3D-CRT technology to target the cancer.
  • Internal radiation therapy. Radioactive materials are placed into the vagina, prostate, or other areas where the cancer cells are found. Internal radiation therapy is also called brachytherapy (say "bray-kee-THAIR-uh-pee"). Radiation for internal use may be sealed inside of needles, seeds, wires, or catheters.
    • High-dose rate brachytherapy (HDR brachytherapy): Radioactive material is placed into an organ, such as the prostate, for a very brief period of time (seconds to minutes) and then removed.
    • Low-dose rate brachytherapy (LDR brachytherapy): Radioactive material is placed into an organ, such as the prostate, and left there permanently.
  • Systemic radiation therapy. Radioactive material (such as radioactive iodine) is given by mouth or into a vein, so it travels in the blood to tissues throughout the body.
  • Fractionated radiation therapy. Sometimes the total amount of radiation that a person needs is split into smaller amounts and given more often. Or it can be given in bigger amounts over a shorter period of time.
    • Hyperfractionated therapy: Lower doses of radiation are given more often, such as twice a day rather than once a day. The number of treatment days is the same.
    • Hypofractionated therapy: Higher doses of radiation are given once a day (or less often) over fewer treatment days. For example, radiation therapy that normally takes 5 weeks could be given in 3 weeks.

Radiation therapy may be given before surgery to shrink a tumor, such as with bladder cancer. Or it may be given during surgery or while you are getting chemotherapy. Or it may be given after other treatment, such as after surgery for breast cancer.

Radiation therapy may be given when a person with cancer is not well enough for other treatment, such as surgery. Radiation therapy is also used in palliative care for advanced or metastatic cancer. For example, it can relieve pain by shrinking tumors in the bones.

Other kinds of radiation therapy

Stereotactic body radiation therapy (SBRT). This therapy very precisely targets a tumor anywhere in the body while minimizing damage to normal tissue around the tumor. It can be used for small to mid-sized tumors. A single treatment or several treatments are all that may be needed.

Proton therapy. This kind of radiation therapy is used mostly in clinical trials. Proton therapy uses a type of energy (protons) different from X-rays. This allows a higher amount of specifically directed radiation, which may provide more protection to nearby healthy tissues. Sometimes proton therapy is combined with X-ray therapy.

Targeted radiation therapy. This therapy uses monoclonal antibodies to deliver radiation directly to cancer cells. This treatment is used with non-Hodgkin's lymphoma.

What To Expect

Recovery depends on the tumor site, the stage and grade of the cancer, and the amount of healthy tissue that is affected during treatment. Damage to normal cells during radiation therapy may cause side effects.

Skin changes

Skin changes are common with radiation therapy. The skin in the area of your body that is getting radiation may turn red and tender, itch, peel, or blister. Toward the end of treatment, the skin may become moist and "weepy." These effects are temporary, and the area will gradually heal when treatment is completed. You may notice a slight change in the color of the skin.

Good skin care is important during radiation therapy. And you should check with your doctor before using any deodorants, lotions, or creams on the treated area. To care for your skin:

  • Use lukewarm water for showers or quick baths. Pat yourself dry with a soft towel, being careful not to rub off any ink marks that are used for your radiation.
  • Avoid putting heating pads or cold packs or anything that is hot or cold on this skin.
  • Wear soft cotton clothes that are loose on your body.
  • Ask your doctor about different types of gels or lotions that can help protect your skin or help make you feel more comfortable.
  • Protect your skin from the sun by staying out of the sun and wearing a hat with a wide brim, long sleeved-shirts, and long pants when you are outdoors. Talk to your doctor about wearing sunscreen.


Fatigue is a common side effect of radiation therapy. It is a sense of tiredness that doesn't seem to go away, even with rest or sleep. Some people may only have mild fatigue. For others, fatigue may be a bigger problem. It may last from 6 weeks to a year after your last radiation treatment.

Staying active can lift your mood and help you feel better. It can also help reduce problems with anemia during treatment. It's fine to be active in blocks of 10 minutes or more throughout your day. Walking with a friend can help you keep a routine.

Be patient. It can take time to fully recover. Balancing rest with activity is important. Try to match your activities to your energy levels.

Throat changes

Radiation to the neck or chest can irritate the lining of your throat and esophagus. It may be hard to swallow, and you may feel like you have a lump in your throat or a burning feeling in your throat or chest. You may also develop a cough.

Having both radiation and chemotherapy can make this worse. So can smoking or drinking alcohol during the time you are getting radiation therapy. These symptoms usually go away within a month after radiation treatment is completed.

Why It Is Done

Radiation therapy is used to destroy cancer cells and to shrink tumors.

How Well It Works

Radiation is one of the main treatments used to kill cancer cells. But it doesn't always cure cancer. Researchers continue to study safer and more effective ways to use radiation therapy to treat cancer.


Radiation therapy may shrink a tumor, give you relief from cancer symptoms, or possibly cure cancer. But it has risks for serious side effects. Your doctor will recommend radiation therapy if he or she thinks that the benefit you may have from this treatment is greater than the risks.

Risks of radiation therapy during and right after treatment include:

  • Fatigue.
  • Nausea with or without vomiting.
  • Skin changes, such as turning red and flaking, peeling, or shrinking (radiation dermatitis).
  • Problems that are specific to the area being treated. One example is hair loss with radiation to the head or neck. Another example is urinary problems if the lower abdomen is radiated.

Most of these problems will go away soon after the treatment ends. But sometimes the side effects are permanent, such as when the salivary glands are damaged.

And sometimes side effects may show up months or years after radiation therapy. These can include:

  • Skin changes (from external radiation treatments).
  • Damage to the bowels that causes diarrhea and bleeding or an obstruction.
  • Chronic bladder or rectal irritation.
  • Vaginal scarring (vaginal fibrosis).
  • Memory loss.
  • Infertility (not being able to become pregnant or father a child).
  • Harm to your lungs or heart.
  • In rare cases, a second cancer caused by exposure to radiation.

What To Think About

For more information about the side effects from radiation therapy and ways to cope with them, read "Radiation Therapy and You: Support for People With Cancer" from the National Cancer Institute. You can find this booklet online at www.cancer.gov/cancertopics/radiation-therapy-and-you.


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