- Effects of treatment with megestrol acetate, aminoglutethimide, or formestane on insulin-like growth factor (IGF) I and II, IGF-binding proteins (IGFBPs), and IGFBP-3 protease status in patients with advanced breast cancer. Frost, V.J., Helle, S.I., Lønning, P.E., van der Stappen, J.W., Holly, J.M. J. Clin. Endocrinol. Metab. (1996)