Radiation Therapy for Breast Cancer

Radiation given from a machine outside the body, known as external-beam radiation therapy, is the most common type of radiation therapy used for breast cancer. A radiation oncologist will have oversight of your radiation therapy. He or she will determine the dose of radiation to be used at each session and carefully calculate the optimum delivery of x-ray beams to target the tumor while minimizing the effect of radiation on nearby healthy tissue. Radiation therapy is usually given 5 days a week for 3 to 8 weeks; each treatment session lasts 30 minutes or less and is painless. Treatment with radiation does not cause a person to become radioactive.

Radiation therapy is almost always done after lumpectomy to make sure that any remaining cancer cells are destroyed. Studies have shown that women with a small tumor who have a lumpectomy followed by radiation therapy live as long as women who have mastectomy.

Radiation therapy can be safely avoided by many women who have mastectomy. The need for adjuvant radiation therapy after mastectomy is determined primarily by the number of involved lymph nodes, as well as the size of the tumor and whether cancer cells were found in the margin of healthy tissue around the tumor. Adjuvant radiation therapy is usually given in small doses once a day over the course of several weeks. If breast cancer has metastasized, radiation therapy may be given to another part of the body.

Radiation therapy kills cancer cells because they are rapidly dividing cells; unfortunately, other cells in the body also rapidly divide, and radiation may damage them as well. Healthy cells that rapidly divide include cells in the bone marrow (where blood cells are made), the lining of the mouth and intestines, the hair, and skin. Side effects may result from damage to healthy cells, but there are now many ways to reduce or avoid these side effects. (Refer to the section on side effects beginning on page 17.) You will have blood drawn before each treatment session to make sure you have a sufficient amount of blood cells. If the number is low, your treatment may be delayed to give your body time to make more healthy blood cells.

• American Cancer Society: www.cancer.org, Detailed Guide to Breast Cancer; Breast Cancer Profiler Tool(decision-making tool)
• ASCO's patient Web site: www.cancer.net, Breast Cancer: Treatment
• American Society for Radiation Oncology's patient Web Site: www.rtanswers.org, Answers to Your Radiation Therapy Questons
• Breastcancer.org: www.breastcancer.org, Treatment and Side Effects
• Susan G. Komen for the Cure: www.komen.org, Understanding Cancer: Treatment

• Experiencing Radiation Therapy for Breast Cancer