ERBB2 and breast cancer: Here, we found that HER2-positive breast cancer patients had the highest ratio of Treg : Th17 cells (Figure 3; 35.5 : 1, Treg : Th17 compared with 8 : 1 in healthy donors; P=0.006); HER2-negative patients had a similar balance of Treg : Th17 compared with healthy donors (14 : 1 compared with 8 : 1; P=0.26).