A lumpectomy (the older name), or wide local excision, is a removal of any kind of lump from the breast; it is a common treatment of breast cancer by surgically removing the cancerous tumor and a small amount of tissue around it, rather than the entire breast as in mastectomy. It is sometimes called "Breast-conserving surgery" since it mimimizes the amount of flesh removed. It's generally done along with radiotherapy to attempt to destroy any cancer cells that have spread from the original tumor, but mastectomy is more likely if there are multiple tumors or if for some reason the patient can't take radiation therapy.

When a tumor and about a centimeter of surrounding tissue is removed, a clear fluid called "seroma" usually fills the space naturally after the surgery, and is eventually replaced by scar tissue. (Very rarely, seromas continue to recur and have to be drained occasionally by a doctor.) If the tumor is large enough to be more than a quarter of the size of the whole breast, surgeons will usually recommend mastectomy instead. Both procedures are often combined with removal of some of the underarm lymph nodes, which are often the first place breast cancer spreads to.

The surgery itself is relatively brief and can be done in an outpatient clinic, although the patient would probably have to return to have the sutures removed later. The radiation therapy would be done over the next five or six weeks after the procedure. The breast is often a little different in shape than it was previously; there are padded shells available to fit inside a bra and balance out the difference from the other breast.

Lumpectomies have become a lot more common since the mid-1980s when studies showed that it gave the same chance of survival as mastectomies for small or localized cancer. In fact, a biopsy is often effectively a lumpectomy if cancer is strongly suspected, since the suspected cancer can be removed for the purpose of testing it. The body shape and sex life are usually less disturbed by a lumpectomy, although studies seem to show that people with breast cancer have the same psychological issues to deal with no matter which type of removal is done. The decision is generally left to the patient these days.

Though lumpectomy was uncommon for a long time, the first known successful breast cancer cure by surgery was what would now be called a lumpectomy. In 1697, Dutch physician Adrian Helvetius published "Letter on the Nature and Cure of Cancer," describing the case of a forty-eight-year-old Englishwoman he had treated. He had recommended surgery the first time he examined her, but she was too scared and tried many other supposed remedies over a six-month period, while the growth in her breast grew from the size of a walnut to the size of a fist. Finally she agreed to the surgery, which went "without great pain, without cries, without the appearance of weakness, without the slightest danger, without spilling more than two palettes of blood, with ease, facility, and promptness." All that was removed was the hardened mass, but apparently the woman's scar healed and her health went back to normal.

Yalom, Marilyn. A History of the Breast. New York: Alfred A. Knopf, 1997.