 Prostate cancer, the most frequently diagnosed cancer among occidental men, is associated with a major individual and societal burden. Although still controversial, the literature suggests that a high consumption of omega-3 fatty acids ω3 has protective effects against prostate cancer. One of the proposed mechanisms of action of ω3 lies in their anti-inflammatory properties. In addition, there are some observational evidences suggesting an association of ω3 intake with a lower rate of depression in cancer patients. However, no clinical study has tested the efficacy of ω3 supplementation on psychological and quality of life outcomes in that population. Several evidences point to a possible involvement of inflammation in psychological issues. Reducing the systemic inflammatory state may have beneficial impact on the quality of life of these patients. Preliminary work from this team of investigators, in a cohort of patients managed with active surveillance for their low-grade prostate cancer, show a strong inverse association between the risk of prostate cancer progression to high-grade and the level of prostatic eicosapentanoic acid EPA- a type of ω3. 