Why it's done

Radiation therapy kills cancer cells. It's often used after surgery to reduce the risk that the cancer will come back. It can also be used to provide relief from pain and other symptoms of advanced breast cancer.

Radiation after lumpectomy

If you're having an operation to remove the breast cancer and leave the remaining breast tissue intact (lumpectomy or breast-conserving surgery), your doctor may recommend radiation after your procedure to kill any cancer cells that might remain. Adding radiation after a lumpectomy reduces the risk that cancer will return in the affected breast.

Lumpectomy combined with radiation therapy is often referred to as breast conservation therapy. This type of treatment is as effective as having all the breast tissue removed (mastectomy). In special situations where the risk of recurrence is very low, your doctor may also discuss the option of avoiding radiation after a lumpectomy.

After lumpectomy, radiation treatment options might include:

• Radiation to the entire breast. One of the most common types of radiation therapy after a lumpectomy is external beam radiation of the whole breast (whole-breast irradiation).
• Radiation to part of the breast. Radiation therapy to part of the breast (partial-breast irradiation) may be an option for some early-stage breast cancers. This technique directs internal or external radiation to the area around where the cancer was removed.

Radiation after mastectomy

Radiation can also be used after mastectomy. In this situation, the radiation can kill any cancer cells that might remain and reduce the risk that the cancer may recur in the remaining tissues of the chest wall or lymph nodes.

When determining whether you should undergo radiation after mastectomy, your doctor considers whether you have:

• Lymph nodes with signs of breast cancer. Underarm (axillary) lymph nodes that test positive for cancer cells are an indication that some cancer cells have spread beyond the breast.
• Large tumor size. A breast cancer larger than about 2 inches (5 centimeters) generally carries a higher risk of recurrence than do smaller cancers.
• Tissue margins with signs of breast cancer. After breast tissue is removed, the margins of the tissue are examined for signs of cancer cells. Very narrow margins or margins that test positive for cancer cells are a risk factor for recurrence.

Radiation for locally advanced breast cancer

Radiation therapy can also be used to treat:

• Breast cancers that can't be removed with surgery.
• Inflammatory breast cancer, an aggressive type of cancer that spreads to the lymph channels of the skin covering the breast. This type of cancer is typically treated with chemotherapy before a mastectomy, followed by radiation, to decrease the chance of recurrence.

Radiation for managing metastatic breast cancer

If your breast cancer has spread (metastasized) to other parts of your body, radiation therapy may be recommended to shrink the cancer and help control symptoms such as pain.