IGF1 and neoplasm: Furthermore, the ability of CR to regulate IGF-1 levels and the Insulin/IGF-1 pathway could also be responsible for its anti-tumor effect as an elevated IGF-1 serum level is associated with an increased risk of breast, prostate, colon, and lung cancer in humans (Chan et al., 1998; Hankinson et al., 1998; Schaefer et al., 1998; Wolk et al., 1998; Ma et al., 1999; Yu et al., 1999).