In breast cancer patients, it has been shown that the ratio of the “memory” T cell compartment (CD45RO+) compared to naïve T cells in the bone marrow was significantly increased for both CD4+ and CD8+ T cells in patients compared to healthy controls, with the greatest increase in memory phenotype CD4+ T cells in bone marrow of patients where disseminated tumor cells were detected. This evidence concerns the gene CD8A and breast carcinoma.