Breast Reconstruction After Mastectomy For Cancer Breast deformities left after various forms of breast cancer surgery may be reconstructed and restored to a natural appearing breast, matching the remaining one. As it is difficult to match a large, droopy or very small opposite breast by breast reconstructive procedures, the opposite breast often requires adjustment as part of the reconstruction as well in order to achieve a natural symmetrical result. Currently most breast reconstruction operations are started at the time of mastectomy if the cancer treatment will allow this..