Fish oil, lean tissue, and cancer: Is there a role for eicosapentaenoic acid in treating the cancer anorexia/weight loss syndrome?

Eicosapentaenoic acid is an omega-3 fatty acid, a group of fatty acids characterized by a double bond that sits three carbons down from the n terminal of the molecule. Derived from dark, rich fish, eicosapentaenoic acid has received increasing attention as a therapy for the cancer anorexia/weight loss syndrome. Multiple studies, including laboratory and preliminary clinical studies suggest this fish oil derivative may benefit cancer patients. Recently, however, three large comparative studies suggest that eicosapentaenoic acid is relatively ineffective for treating this syndrome. In view of these recent results, the goals of this review are as follows: (1) to provide background on the mandate for further study of the cancer-associated anorexia/weight loss syndrome; (2) to review the preliminary data that have suggested that eicosapentaenoic acid is a promising agent for treating this syndrome; (3) to review the methodology and findings of the more recent, definitive clinical trials; (4) to discuss and speculate on why the earlier positive findings drew conclusions that are discrepant from the results of more recent comparative clinical studies.