SEER Training Modules

Radiation Therapy

A lumpectomy is followed usually by radiation therapy. During radiation therapy, high-energy x-rays are used to destroy cancer cells that may still be present in the affected breast or in nearby lymph nodes.

Radiation therapy may also be used to shrink tumors before surgery. Radiation therapy alone or in combination with chemotherapy can be used preoperatively or in lieu of surgery to destroy cancer cells and shrink tumors.

Following lumpectomy, radiation therapy to the breast and sometimes to the axilla is administered five days a week for four to six weeks. A concentrated or "boost" dose of radiation may be delivered by special implants (applicators) containing radioactive seeds, or external beam radiation.

There are times when radiation therapy is used postoperatively. This often occurs when the tumor is larger than 2 centimeters, or cancer is found in multiple lymph nodes in the axilla, or the tumor is close to the rib cage or chest wall muscles.

Intense exposure to radiation does have unavoidable side effects, including particularly fatigue, swelling, and skin changes, which gradually disappear in most cases. More serious side effects include heart and lung damage, lymphedema, and an increased risk of second malignancies.

To learn more about radiation therapy, see the Cancer Treatment module.