Decision time: bilateral mastectomy with recon OR radiotherapy

A mastectomy doesn't prevent metastases. It does however lower the risk of local recurrence in that breast (which can happen) or a new primary breast cancer in that or other breast . My Aunt ...BRAC1, had primary breast cancer, 2 diff types in 2 breasts and ovarian cancer. She died from the 2 bc, sadly after being treated effectively for her 1st bc and ovarian cancer. 

http://www.breastcancer.org/risk/factors/genetics