Trial Information

Comparison Study of a Low-Fat Diet Supplemented With Fish Oil and a Standard Western Diet in Individuals With Prostate Cancer

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.