Low-Fat Diet and/or Flaxseed in Preventing Prostate Cancer

OBJECTIVES: * Compare tumor proliferation in patients with newly diagnosed prostate cancer eating fat- and/or flaxseed-modified diets. * Compare differences in histopathological markers associated with prostate cancer (rates of apoptosis, extent of high-grade prostatic intraepithelial neoplasia) among patients in these diet groups. * Compare changes in serum prostate specific antigen among patients in these diet groups. * Compare changes in hormone-related factors (total serum testosterone and free androgen index, insulin-like growth factor \[IGF\], and IGF-binding protein-3) among patients in these diet groups. * Compare the effects of diet on nutritional biomarkers (levels of lignans in the urine and ejaculate, fatty acid profiles of erythrocytes and prostatic tissue) in these patients. * Determine associations between dietary modification and changes in dietary biomarkers, hormonal intermediates, and study endpoints in these patients. OUTLINE: This is a randomized study. Patients are stratified according to Gleason score (less than 7 vs at least 7) and race (black vs non-black). Patients are randomized to 1 of 4 diet groups. * Arm I (Flaxseed-supplemented diet): Patients are instructed to incorporate ground flaxseed into their daily diets. * Arm II (Low-fat diet): Patients are instructed on ways to achieve a diet with no greater than 20% of total energy from dietary fat. * Arm III (Flaxseed-supplemented, low-fat diet): Patients are instructed as in arm I and arm II. * Arm IV (Control diet): Patients are contacted weekly, but do not receive dietary counseling until after surgery. All patients ingest the diets for at least 3 weeks and complete diet diaries until surgery. After surgery, all patients receive dietary counseling. PROJECTED ACCRUAL: A total of 160 patients (40 per treatment arm) will be accrued for this study.