FOXP3 and breast cancer: Some studies have reported that the balance of FOXP3+ TILs and other TILs is associated with breast cancer prognosis [27,28,29,30,31]; additionally, some studies have shown that FOXP3+ Tregs have heterogeneous subpopulations; “effector” Tregs (eTregs) have played roles in impeding antitumor immune responses, whereas “non-Tregs” play a role in antitumor immune responses [32,33,34].