In inverse-variance weighted (IVW) models, genetically proxied bioavailable testosterone was associated with overall (OR:1.16, 95% CI:1.04–1.28, p = 6.53x10−3), luminal A-like (OR:1.28, 95% CI:1.14–1.45, p = 5.27x10−5), and luminal B HER2 negative-like breast cancer risk (OR:1.18, 95% CI:1.03–1.36, p = 0.02) (Figure 5, Table S6). Here, ERBB2 is linked to breast cancer.