For ER+ BC, the main risk factors identified are FGF1 (OR 1.055, 95% CI: 1.005–1.107, P = .029) and FGF7 (OR 1.068, 95% CI: 1.007–1.133, P = .028); no causal relationships were observed in ER− BC. This evidence concerns the gene FGF1 and breast cancer.