Radiation Treatment for Cancer

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Radiation Treatment for Cancer

Treatment Overview

Radiation therapy uses high energy rays, such as X-rays, to destroy cancer cells and shrink tumours. Radiation damages the genetic material of cancer cells. This 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.
    • For 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.
  • 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.

Radiation therapy may be given before surgery to shrink a tumour, 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 tumours in the bones.

Other kinds of radiation therapy

Hyperfractionated radiation therapy. This radiation therapy uses lower doses that are given more often, such as twice a day rather than once a day. This may increase the side effects while having treatment. But it may cause fewer long-term side effects.

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 After Treatment

Recovery depends on the tumour 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.

Why It Is Done

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

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 tumour, 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. Radiation to the pelvic area may cause vaginal dryness in women and erection problems in men.

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).
  • 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 U.S. National Cancer Institute. You can find this booklet online at www.cancer.gov/cancertopics/radiation-therapy-and-you.

Complete the special treatment information form (PDF) (What is a PDF document?) to help you understand this treatment.


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Specialist Medical Reviewer Christopher G. Wood, MD, FACS - Urology, Oncology
Last Revised July 5, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.