Understanding double mastectomy
Removing both breasts
The short version
A double mastectomy removes both breasts — the one with cancer and, often by choice, the unaffected one, sometimes to reduce the risk of a future cancer, particularly for people with an inherited gene change or strong family history.
A double (bilateral) mastectomy removes both breasts. This may be recommended when cancer is found in both breasts, or chosen by a patient to also remove the unaffected breast — sometimes called a contralateral prophylactic mastectomy — often considered for people with a known inherited gene change like BRCA1/2 or a strong family history.
Removing the unaffected breast does not treat the existing cancer — it is a separate, personal decision about future risk, and is worth discussing thoroughly with your surgeon and, where relevant, a genetic counselor.
Questions you may want to ask
Does genetic testing or my family history affect this decision?
What are the trade-offs of removing the unaffected breast?