People carrying BRCA1 and BRCA2 gene mutations are at high risk of developing breast and ovarian cancer. Researchers have found that changes occur in the immune cells of breast tissue in carriers of BRCA1 and BRCA2 mutations long before breast cancer develops. This raises the possibility of early intervention to prevent the disease, as an alternative to risk-reduction surgery. Drugs already approved for late-stage breast cancer treatment could reactivate the faulty immune cells and keep the breast cells healthy. If successful in mouse models, this preventative therapeutic approach could pave the way for clinical trials in human carriers of BRCA1 and BRCA2 mutations.