IGF1 and cancer: Perhaps most interestingly, a few studies have also reported a more complex U‐shaped relationship between IGF‐1 and all‐cause (Andreassen et al., 2009), cardiovascular (Burgers et al., 2011), and cancer mortality (Svensson et al., 2012), in which individuals with the highest and lowest levels of IGF‐1 tend to have worse outcomes.