The role of endocrine insulin-like growth factor-I and insulin in breast cancer.

Epidemiologic studies demonstrate that breast cancer is the most common type of cancer diagnosed in women and is a significant cause of morbidity and mortality. While there are many risk factors known to be associated with increased breast cancer risk, this review will focus specifically on circulating IGF-I, hyperinsulinemia, and type 2 diabetes. Their effects on promoting breast cancer development, progression, and adverse outcomes have been demonstrated in both animal and human studies, suggesting that the IGF system is a potential target for breast cancer therapy. In addition, in the clinical setting, emphasizing metabolic risk modifications to patients including weight loss, dietary changes, and diabetes control may also play an important role in breast cancer risk reduction.