INS and breast cancer: Using individual ORs adjusted for age at least, there was no increased risk of breast cancer when the higher quartiles were compared with the lowest quartile (Q1) of fasting insulin (Q2 vs Q1, 7 studies, n = 2,045; Q3 vs Q1, 7 studies, n = 2,125; Q4 vs Q1, 6 studies, n = 2,112) (OR Q2 vs Q1 0.96, 0.71 to 1.28; OR Q3 vs Q1 1.22, 0.91 to 1.64; OR Q4 vs. Q1 0.98, 0.70 to 1.38) (Figures 3A, 3B and 3C, respectively).