Genome-wide association studies have indicated that polymorphisms in the NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme that breaks down PGE2 into biologically inactive 15-keto-PGE2, are associated with higher risk for CRC, whereas polymorphisms in PTGER2 were associated with lower CRC risk (Hoeft et al., 2010). This evidence concerns the gene HPGD and colorectal carcinoma.