CRP and breast cancer: Heterogeneity test showed some significant differences for causal estimation between CRP level and all BC risk (IVW, Q (df) 86.0435, P = 3.47E−06; MR-Egger, Q (df) 82.2934, P = 6.97E−06), ER + BC (IVW, Q (df) 95.0435, P = 1.89E−07; MR-Egger, Q(df) 93.6034, P = 1.79E−07), and ER-BC (IVW, Q (df) 50.0635, P = 0.0475; MR-Egger, Q (df) 49.5434, P = 0.0414).Thus, random-effects MR estimates were applied to these models.