FGF4 and breast cancer: The inverse-variance weighting analysis showed that for overall BC, FGF20 showed a genetically protective effect (odds ratio [OR] 0.996, 95% CI: 0.993–1.000, P = .027), FGF4 can genetically promote the risk of BC (OR 1.004, 95% CI: 1.001–1.007, P = .013).