FAS and breast cancer: Considering the fact that CD45RO expression increases in parallel with differentiation in memory cells, these findings along with the increased expression of CD95 on TCM and their subsets in patients with advanced tumors (i.e. higher stage, higher grade, and more tumor-involved nodes) suggest that in BC, although the immune system tries to provide a pool of effective memory cells against the tumor, interactions with, or signals from, transformed cells and the tumor microenvironment lead to changes that diminish the host’s ability to eradicate the tumor.