Given that impaired DNA repair such as deficiency in BRCA1 results in genomic instability and susceptibility to genotoxic stress, and consequently leads to the increase of somatic mutations and neoantigens, we sought to answer the question whether the expression of BRCA1 and CCND1 modifies the effect of T cell activation on patients’ survival in breast cancer. The gene discussed is BRCA1; the disease is breast cancer.