IRS1 and breast cancer: However, our null results with regard to the relationship between variants of the IGFBP3, IGF1R, IRS1, and PI3KCB genes and, overall, premenopausal and postmenopausal breast cancer risk in European and East Asian women are in concordance with the findings from analyses in the Breast and Prostate Cancer Cohort Consortium (23, 37) and recent GWAS publications (38, 39).