CYP2R1 and rectal cancer: In addition to SMAD7 (P = 0.0005) and SMAD3 (P = 0.0003), several other genes or genetic regions (CYP2R1, CHAF1A, CREBBP, IL10, SNPs identified in genome-wide association studies (GWAS) to be associated with IGF levels, IGFBP2/IGFBP5, IGFBP3, and C-MYC region) were associated with rectal cancer.