Phase II Prospective Randomized Trial of a Low-Fat Diet With Fish Oil Supplementation in Men Undergoing Radical Prostatectomy

Cancer Prev Res (Phila). 2011 Dec;4(12):2062-71. doi: 10.1158/1940-6207.CAPR-11-0298. Epub 2011 Oct 25.

Abstract

Preclinical studies suggest lowering dietary fat and decreasing the ratio of omega-6 to omega-3 polyunsaturated fatty acids decreases the risk of prostate cancer development and progression. We conducted a phase II randomized trial to test the effect of decreasing dietary fat combined with decreasing the dietary omega-6:omega-3 ratio on biomarkers related to prostate cancer development and progression. Patients undergoing radical prostatectomy were randomly assigned to receive a low-fat diet with 5 grams of fish oil daily (dietary omega-6:omega-3 ratio of 2:1) or a control Western diet (omega-6:omega-3 ratio of 15:1) for four to six weeks prior to surgery. The primary endpoint was change in serum insulin-like growth factor I (IGF-1) between arms. Secondary endpoints were serum IGFBP-1, prostate prostaglandin E2 levels, omega-6:omega-3 fatty acid ratios, COX-2, and markers of proliferation and apoptosis. Fifty-five patients were randomized and 48 completed the trial. There was no treatment difference in the primary outcome. Positive secondary outcomes in the low-fat fish oil versus Western group were reduced benign and malignant prostate tissue omega-6:omega-3 ratios, reduced proliferation (Ki-67 index), and reduced proliferation in an ex vivo bioassay when patient sera was applied to prostate cancer cells in vitro. In summary, four to six weeks of a low-fat diet and fish oil capsules to achieve an omega-6:omega-3 fatty acid ratio of 2:1 had no effect on serum IGF-1 levels, though in secondary analyses, the intervention resulted in decreased prostate cancer proliferation and decreased prostate tissue omega-6:omega-3 ratios. These results support further studies evaluating reduction of dietary fat with fish oil supplementation on modulating prostate cancer biology.

Publication types

  • Clinical Trial, Phase II
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diet, Fat-Restricted*
  • Dietary Supplements*
  • Fatty Acids, Omega-3 / administration & dosage*
  • Fatty Acids, Omega-3 / blood
  • Fatty Acids, Omega-6 / administration & dosage*
  • Fatty Acids, Omega-6 / blood
  • Fish Oils / administration & dosage*
  • Humans
  • Immunoenzyme Techniques
  • Insulin-Like Growth Factor Binding Protein 1 / blood
  • Insulin-Like Growth Factor I / metabolism
  • Male
  • Middle Aged
  • Prognosis
  • Prospective Studies
  • Prostatectomy
  • Prostatic Neoplasms / diet therapy*
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / surgery

Substances

  • Fatty Acids, Omega-3
  • Fatty Acids, Omega-6
  • Fish Oils
  • Insulin-Like Growth Factor Binding Protein 1
  • Insulin-Like Growth Factor I