The goal of breast cancer surgery is to remove the entire tumor from the breast. Some of the lymph nodes in the underarm area may also be removed to see if they contain cancer. The goal of radiation therapy is to kill any remaining cancer cells in the breast or nearby lymph nodes after surgery.

There are 2 main types of surgery for breast cancer: lumpectomy, or breast-conserving surgery, and mastectomy.

With lumpectomy, the surgeon removes only the tumor and a small rim of normal tissue surrounding it, referred to as the margin. Radiation therapy is almost always given after a lumpectomy.

There are two main types of mastectomy: total mastectomy, also called simple mastectomy, and modified radical mastectomy. In a total or simple mastectomy, the surgeon removes the entire breast and the lining of the chest muscle, but no other tissue. In a modified radical mastectomy, the surgeon removes the entire breast, the lining of the chest muscles and the lymph nodes in the underarm area.

Many women who have a mastectomy don’t need radiation therapy. However, in some cases, radiation therapy is used after mastectomy to treat the chest wall and lymph nodes.

Radiation therapy uses targeted, high energy X-rays or other forms of radiation to kill cancer cells. Radiation therapy can harm normal tissue, so it’s carefully planned and precisely given.

Each treatment session lasts about 10-20 minutes. Treatment is most often given once a day, five days a week, for 1 to 6 weeks. After a lumpectomy, many women now get hypofractionated whole-breast radiation therapy which uses a slightly higher dose of radiation per session. This reduces the number of treatment sessions and shortens the overall course to 5 days a week, for 1-4 weeks.