Mastectomy (from Greekμαστός "breast" and ἐκτομήektomia "cutting out") is the medical term for the surgical removal of one or both breasts, partially or completely.
A mastectomy is usually carried out to treat breast cancer. In some cases, people believed to be at high risk of breast cancer have the operation prophylactically, that is, as a preventive measure. It is also the medical procedure carried out to remove cancerous tissues. Alternatively, some patients can choose to have a wide local excision, also known as a lumpectomy, an operation in which a small volume of breast tissue containing the tumor and a surrounding margin of healthy tissue is removed to conserve the breast.
Both mastectomy and lumpectomy are referred to as "local therapies" for breast cancer, targeting the area of the tumor, as opposed to systemic therapies, such as chemotherapy, hormonal therapy, or immunotherapy.
Traditionally, in the case of breast cancer, the whole breast was removed. Currently, the decision to do the mastectomy is based on various factors, including breast size, the number of lesions, biologic aggressiveness of a breast cancer, the availability of adjuvant radiation, and the willingness of the patient to accept higher rates of tumor recurrences after lumpectomy and radiation. Outcome studies comparing mastectomy to lumpectomy with radiation have suggested that routine radical mastectomy surgeries will not always prevent later distant secondary tumors arising from micro-metastases prior to discovery, diagnosis, and operation.