Radiation Therapy for Cancer

Topic Overview

What is radiation therapy?

Radiation therapy uses high doses of radiation to destroy cancer cells (tumours). Radiation damages the genetic material of cells in the area being treated, leaving the cells unable to continue to grow. Although radiation damages normal cells as well as cancer cells, the normal cells usually can repair themselves and function, while the cancer cells cannot.

Radiation therapy is used for many different types of cancers, such as bladder cancer, endometrial cancer, and prostate cancer.

What types of radiation therapy are there?

Radiation is delivered in one of two ways.

• Brachytherapy, or internal radiation therapy, involves inserting radioactive material directly into or near the tumour. The radioactive material is either later removed or left in place. Removable radiation sources are inserted with needles or small thin tubes. Sometimes the material is left in your body (permanent brachytherapy). In this case, small beads containing the radioactive material are inserted into the tumour. The beads release radiation at the site of the tumour over a few days or weeks, after which they are no longer radioactive.
• External radiation therapy, or teletherapy, uses a beam of radiation directed at the tumour. Once the area of cancer is identified, a small ink tattoo is fixed on the skin over the area of cancer so that the radiation beam can be focused on the same spot for each treatment. It's necessary to focus the radiation beam on the cancer cells and to shield nearby healthy tissue from the radiation. External radiation therapy is usually done in multiple treatments, usually once a day for 5 to 6 days a week for several weeks.

Does radiation therapy have side effects?

Radiation therapy has side effects. The most common ones include:

• Fatigue.
• Hair loss near the treated area.
• Skin darkening in the area exposed to a beam of radiation.

If the cancer being treated is in your abdomen or pelvis, you may also experience:

• Nausea, vomiting, and diarrhea.
• Loss of appetite.
• Bladder and intestinal irritation.
• Painful urination.
• Vaginal dryness in women and erection problems in men.
• Radiation enteritis, in which nausea, vomiting, and diarrhea that occurred during or immediately after radiation therapy continue. This can cause inflammation in the intestine, resulting in long-term diarrhea.

How long do side effects last?

Side effects generally go away after the treatment is finished but can be quite disabling during treatment.

Long-term effects of radiation in the pelvic area or abdomen can include:¹

• Bowel obstruction.
• Abdominal cramps.
• Frequent bowel movements or diarrhea.
• Chronic bladder or rectal irritation.
• Vaginal scarring (vaginal fibrosis).
• Skin changes (from external radiation treatment).

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Author:	Kathe Gallagher, MSW Carrie Henley	Last Updated: February 21, 2007
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Ross Berkowitz, MD - Obstetrics and Gynecology Andrew Swan, MD, CCFP, FCFP - Family Medicine
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