The long term goal of this research is to develop topical therapy for cancer with eicosapentaenoic acid (EPA), which has been shown to have anti-inflammatory and anti-tumorigenic properties. EPA has no known side effects other than a mild increase in bleeding time. This project will develop the technology for purifying an EPA-bearing lipid from cultured murine algae and test its effectiveness in reducing nevi and/or papilloma development in two murine models of cancer, both initiated with dimethylbenz(a)anthrazine. SENCAR mice, which are particularly sensitive to squamous cell carcinoma, will be promoted with 12-O- tetradecanoylphorbol-13-acetate. SKH hairless mice, which are sensitive to melanoma induction, will be promoted with UVB irradiation. Phase II will focus on production scale-up, development of application vehicles, toxicity testing, and longer term animal testing. Potential commercial application includes topical therapy for skin cancer as well as epithelial cancers, such as occur in the rectum and esophagus.