Mastectomy means: Mastectomy is a general term that refers to the surgical removal of breast tissue, which can be used to treat cancerous tissue. It can either be performed in a hospital, or outpatient clinic depending on the extent of the operation. Reconstructive surgery can be done to bring back a normal appearance after a mastectomy. A lumpectomy, which can be combined with radiation or chemotherapy in cases of breast cancer that is not metastatic, may sometimes be performed instead of a mastectomy.
(in Medical Dictionary)

What else does Mastectomy mean?

As a cancer treatment, surgical removal of all or part a breast.
(in Merlin Dictionary)

Radical mastectomy.
(in Merlin Dictionary)