EPA is an efficient COX-1 inhibitor and metabolism by COX (and LOX isoforms) leads to synthesis of 3- and 5-series oxylipins such as PGE3 and LTB5, which have reduced proinflammatory and protumorigenic activity compared with their 2- and 4-series counterparts, perhaps contributing to the anti–colorectal cancer activity of EPA (12–14). This evidence concerns the gene PTGS1 and colorectal cancer.