WAT composition: Lipidome. Among nutrients, dietary lipids are major determinants of the overall lipid composition of WAT, as assessed during dietary intervention studies (19-22). Among fatty acids, essential polyunsaturated fatty acids (PUFAs) are a subclass of bioactive components divided in two groups, n-6 and n-3 fatty acids. The n-6 series include the precursor linoleic acid (LA, 18:2n-6). The n-3 series include the precursor alpha-linolenic acid (ALA, 18:3n-3), and highly unsaturated derivatives. The fatty acid composition of WAT has been shown to reflect the past fatty acid intake (23). Although there are no conclusive studies showing an association between total dietary fat intake and PCa risk, specific types of dietary fat (animal fat) appear to be more significant in increasing PCa risk (6, 28). The association between fish consumption (rich in in the long-chain omega-3 PUFAs) and lower risk of prostate cancer is controversial, but a significant reduction in prostate cancer-specific mortality has been described (29). Previous studies analyzing the PUFAs composition in prostate tissues have led to conflicting results. However, fatty acid composition of WAT has never been studied in PCa in association with aggressiveness and progression.