In the sensitivity analyses, MR-Egger showed no evidence of directional pleiotropy for the associations between inhibition of HMG-CoA reductase (odds [intercept]: 1.00; P = 0.77), NPC1L1 (odds [intercept]: 0.99; P = 0.84), and PCSK9 (odds [intercept]: 1.00; P = 0.72) and breast cancer (Additional file 1: Table S4). Here, PCSK9 is linked to breast cancer.