IGF1 and rectal cancer: Weakly positive association of IGF‐I with colon cancer. Colon cancer cases in third (IGF‐1 of 137–174 ng/mL) and fourth quartile (IGF‐1 > 174 ng/mL) had increased risk compared with controls (OR of 2.2 and 1.8, respectively)No association of IGFI with rectal cancer