CD4 and breast cancer: We analyzed 19 healthy controls and 27 patients (22 testing group and 5 validation group) with breast cancer and revealed distinct populations, including CD3+CD4+ T lymphocytes, cytotoxic T lymphocytes (CTLs; CD3+CD8+), polymorphonuclear myeloid‐derived suppressor cells (PMN‐MDSCs), and monocytic (M)‐myeloid‐derived suppressive cells.