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

RATIONALE: A diet that is low in fat and/or high in flaxseed may slow or prevent disease progression of prostate cancer.

PURPOSE: Randomized phase II trial to study the effectiveness of a diet that is low in fat and/or high in flaxseed in slowing or preventing disease progression in patients who have newly diagnosed 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.

Eligibility Criteria:
DISEASE CHARACTERISTICS:

* Histologically confirmed prostate cancer
* At least 3 weeks until planned prostatectomy (24 days between day 1 visit and surgery)
* Current diet that provides more than 30% of calories from fat

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* Not specified

Life expectancy

* Not specified

Hematopoietic

* Not specified

Hepatic

* Not specified

Renal

* Not specified

Other

* Mentally competent
* Able to speak and write English
* Must have telephone access

PRIOR CONCURRENT THERAPY:

Biologic therapy

* Not specified

Chemotherapy

* Not specified

Endocrine therapy

* No concurrent hormonal therapy

Radiotherapy

* Not specified

Surgery

* At least 2 weeks since prior prostate biopsy

Other

* At least 7 days since prior antibiotics
* No prior therapy for prostate cancer
* No concurrent dietary supplements initiated within the past 3 months or anticipated to begin during study except standard multivitamin/mineral preparations (e.g., One-A-Day, Theragran, or Centrum) that do not supply \> 100% of the recommended daily allowance of any vitamin or mineral
* No other concurrent neoadjuvant therapies
* No other concurrent flaxseed consumption