CRP and breast cancer: Regarding horizontal pleiotropy in MR estimates for CRP and BC, the results demonstrated no evidence of horizontal pleiotropy effects based on the evaluation by the MR-Egger intercept and its P values (All BC, intercept = 0.0036, P = 0.2220; ER + BC, intercept = 0.0026, P = 0.4745; ER-BC, intercept = 0.0024, P = 0.5527).