FOXP3 and breast cancer: A high density of tumor-infiltrating FOXP3 + Tregs has been associated with a poor outcome in various solid tumors, including ovarian, pancreatic, liver, and breast cancers.[26–29] Conversely, in only a few studies, including ours, a favorable prognosis was associated with an increased number of infiltrated Tregs in colorectal and gastric cancers.[30,31] However, the underlying mechanism is not yet clear.