Low-Fat Fish Oil Diet for Prostate Cancer Prevention

1. To establish and validate intermediate biomarkers for prostate cancer prevention trials by conducting a dietary intervention trial of a low-fat diet with omega-3 fatty acid supplements in men undergoing radical prostatectomy. In initial trials it was feasible to intervene with diet and obtain tissue and serum for bioassay and biomarker development. This aim is to study the effect a low-fat, high omega-3 diet has on serum and tissue biomarkers from patients who have prostatectomies for prostate cancer. Ultimately, we hope to identify and validate intermediate markers of efficacy for large-scale dietary prevention trials. 2. To establish and validate insulin growth factor-1 (IGF-1) and insulin growth factor binding proteins (IGFBP) as relevant intermediate biomarkers for prostate cancer prevention trials. IGF-1 is a peptide growth factor that is important to the growth and progression of prostate cancer. To our knowledge, no prospective dietary intervention studies have evaluated the effect of a low-fat diet with omega-3 fatty acid supplements on IGF-1 and IGFBPs, and their potential to serve as relevant intermediate markers for low-fat dietary intervention trials for prostate cancer prevention. 3. To establish and validate serum and tissue fatty acids as relevant intermediate biomarkers for prostate cancer prevention trials. We will evaluate if men randomized to a low-fat, fish-oil-supplemented diet have increased serum ratios of omega-3:omega-6 fatty acids compared with men randomized to a control Western diet before radical prostatectomy. We also will study if patients in the low-fat, fish oil arm have increased ratios of membrane omega-3:omega-6 fatty acids as well as decreased COX-2 and decreased PGE-2 levels in benign and malignant tissue and in visceral fat. If so, it will proved further evidence to support the potential of low-fat fish oil diets for prostate cancer prevention. If serum omega-3:omega-6 ratios correlate with changes in COX-2 and PGE-2 in tissues, then serum omea-3:omega-6 ratios may be useful for monitoring activity and efficacy of low-fat fish-oil-supplemented diets in future trials.