The obtained results supported literature data reporting that BCT is a safe local treatment option to offer to BRCA1 mutation carriers with invasive BC as follows [90]: after adjustment for potential confounders, overall survival rates in patients who performed BCT were similar to those in patients who received a mastectomy, both for BRCA1 mutation carriers (hazard ratio HR = 0.80, confidence interval CI = 0.42–1.51, p = 0.50) and for non-carriers ([HR] = 0.95, [CI] = 0.85–1.07, p = 0.41). This evidence concerns the gene BRCA1 and breast cancer.