In the last decade, data obtained from the European Prospective Investigation into Cancer and Nutrition (EPIC cohort) involving more than 500,000 healthy volunteers have confirmed the association between higher circulating IGF-I levels and the risk of breast cancer in receptor-positive tumors in women older than 50 years, thyroid cancer, low-grade gliomas and acoustic neuromas [64–66]. Here, IGF1 is linked to breast cancer.