Insulin-like growth factor (IGF) level and body size have also been linked to premenopausal BC.33 IGF is modulated by levels of IGF binding protein (IGFBP) and various cytokines, especially adiponectin.34 Vitamin D might increase levels of IGFBP35 and adiponectin,36 both of which may protect against BC.34 In premenopausal women with low body fatness, vitamin D may protect against BC in several ways.37 There may also be unique vitamin D receptor polymorphisms relevant to BC risk in Taiwanese women.38 Here, IGF1 is linked to breast cancer.