IGF1 and breast cancer: The results of our MR analysis of selected hormones on breast cancer are supported by recent MR studies, with similar effects observed for IGF-1 in Murphy et al.51 and SHBG and testosterone in Ruth et al.52 Conversely, the negative association of SHBG adjusted for BMI with breast cancer risk observed in Dimou et al.53 had limited evidence of effect in our study, likely due to sex-specific analysis and differences in sample size.