CD4 and breast cancer: We and others had previously documented the presence of different lymphocyte subsets (T effector cells [CD4+, CD8+], T regulatory cells [Tregs: FOXP3+, CTLA-4+], natural killer cells [NK: CD56+]) infiltrating breast tumours in women with large and locally advanced breast cancers (LLABCs), and showing a significant association (except for FOXP3+ T cells) with a good pathological response, in particular to a pCR, following NAC [21–26, 13].