IGF1 and breast cancer: Notably, in addition to its modifying effect on the association between IGFBP-3 and BC risk, rs12059300 also showed an effect modification on the association between IGF-1 and the risk of BC (Pinteraction < 0.05; adjusted Pinteraction < 0.20); however, this was not discussed in the IGF-1 section because associations inside strata were not statistically significant.