As an example, in metastatic melanoma patients, high concentrations of 12- and 15-hydroxyeicosatraenoic acids (respectively produced by platelet 12-lipoxygenase and cyclooxygenase-1) have been shown to exert pro-malignant effects [2,3,4], and blocking cyclooxygenase-1 by low-dose aspirin is associated with a reduction in risk of several cancer types [5]. This evidence concerns the gene PTGS1 and cancer.