Treatment Overview

Radiation therapy uses high energy rays, such as X-rays, to destroy cancer cells and shrink tumours 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.
  • 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.
  • For 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 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

Stereotactic body radiation therapy (SBRT). This therapy very precisely targets a tumour anywhere in the body while minimizing damage to normal tissue around the tumour. It can be used for small to mid-sized tumours. 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.