IGFBP3 and cancer: Circulating concentrations of IGF‐I and IGFBP‐3 have been associated with risk of type 2 diabetes, cardiovascular diseases, cancer, and mortality in epidemiological studies (Juul et al., 2002; Vasan et al., 2003; Renehan et al., 2004; Kaplan et al., 2007; Friedrich et al., 2009; Burgers et al., 2011; Rajpathak et al., 2012).