What Is a Mastectomy?

Mastectomy is a surgical procedure that removes the whole of one or both breasts, usually to treat breast cancer or to reduce the risk of developing it. It sits within oncologic surgery alongside breast-conserving operations such as lumpectomy, and the choice between the two depends on tumor size and distribution, breast volume, genetic risk, and whether radiation therapy is planned. The operation dates to William Halsted's radical mastectomy of the 1890s, which removed the breast, the pectoral muscles, and the axillary lymph nodes on the assumption that cancer spread outward in an orderly front.

Randomized trials from the 1970s onward showed that less extensive surgery gives equivalent survival, and the field has moved steadily toward tissue preservation. The National Cancer Institute's guidance on mastectomy sets out the current family of procedures, and the radical operation is now rarely performed.

Types of Procedure

A total or simple mastectomy removes the breast tissue, nipple, areola, and overlying skin but leaves the chest wall muscles intact. A modified radical mastectomy adds an axillary lymph node dissection. Skin-sparing mastectomy removes the gland while preserving the skin envelope, and nipple-sparing mastectomy preserves the nipple-areola complex as well, both of which give a better cosmetic result when immediate reconstruction is planned. Surgical technique, margin assessment, and complication rates for these variants are summarized in the StatPearls clinical review of mastectomy. Robotic and endoscopic approaches through small lateral incisions are under active study, with oncologic safety data still accumulating.

Nodal Staging and Reconstruction

Axillary staging accompanies most cancer operations. Sentinel lymph node biopsy, in which a radiotracer or fluorescent dye identifies the first draining nodes, has largely replaced routine full axillary dissection and substantially lowers the incidence of lymphedema. Reconstruction may be immediate, performed during the same anesthetic, or delayed. Implant-based reconstruction uses saline or silicone devices, often staged behind a tissue expander, while autologous techniques transfer skin, fat, and sometimes muscle from the abdomen, back, or thigh as a pedicled or free flap requiring microvascular anastomosis. Patients may also choose to remain flat or to use an external prosthesis.

Risk-Reducing Mastectomy

Bilateral prophylactic mastectomy is offered to people with a strong inherited predisposition, most commonly a pathogenic variant in BRCA1 or BRCA2. The NCI fact sheet on surgery to reduce breast cancer risk reports a risk reduction of at least 95 percent in these groups, with the residual risk arising from breast tissue that cannot be completely excised. Contralateral prophylactic mastectomy in patients with unilateral cancer and no genetic risk factor is more contested, since it lowers the incidence of a second primary tumor without a clear survival benefit. Shared decision making therefore weighs the trade-offs between lumpectomy and mastectomy alongside quality-of-life and body-image outcomes.

Applications

Mastectomy intersects with engineering and computational disciplines in areas including:

• Medical imaging, where MRI, digital breast tomosynthesis, and contrast-enhanced mammography define disease extent before surgery
• Image-guided and robotic surgery, including fluorescence-guided sentinel node mapping
• Biomaterials, covering implant shells, acellular dermal matrices, and tissue-engineered scaffolds
• Three-dimensional surface scanning and printing for reconstruction planning and custom external prostheses
• Clinical decision support, where risk models such as those built from genetic and pathology data inform surgical choice
• Rehabilitation engineering, including bioimpedance and perometry systems for lymphedema monitoring