The term lumpectomy, or partial mastectomy, refers to the removal of the cancerous area of the breast along with a “safety zone” or “cancer free zone” of normal breast tissue around the cancerous area. Other terms applied include “breast preservation” or "breast conservation” surgery. The edge of the cancer free zone is referred to as the “margin”, and studies have shown that there is less of a risk of the cancer coming back (recurrence) if the margin does not show any cancer cells when examined under the microscope.

Most, but not all, women who are diagnosed with breast cancer are eligible for this procedure. Generally women who have cancer in multiple areas of the breast are not eligible, and are better served by having the entire breast removed (mastectomy). In some case, if the tumor is large compared to the size of the breast, it may be necessary to receive chemotherapy before the operation to shrink the tumor. This is not really an extra step, as most women who have larger tumors ultimately receive chemotherapy.

In order to further reduce the risk of recurrence, women who undergo this operation undergo radiation therapy to the breast to treat cells that may have been left behind. It may be necessary, immediately prior to the operation, to place a needle into the cancerous area, for the surgeon to use as a guide during the operation. Small tumors are not visible to the naked eye.

For eligible candidates, long term survival for patients who have had a lumpectomy (partial mastectomy) with radiation is equivalent to those who have had a total mastectomy (total breast removal). The conserved breast must be monitored using x-rays and physical exams, indefinitely, for signs of recurrence.

Most women who have a lumpectomy (partial mastectomy) are discharged the same day of the operation.