IGF1 and breast carcinoma: This is broadly consistent with previous prospective studies that have found IGF-I, as absolute concentrations or relative to IGFBP-3, to be predictive of breast cancer risk in premenopausal women (Hankinson et al, 1998; Toniolo et al, 2000; Krajcik et al, 2002; Muti et al, 2002), although one study found no association between serum IGF-I levels and risk in women who were under the age of 50 years at the time of diagnosis (Kaaks et al, 2002).