Behavior-Based Dietary Intervention in Treating Patients With Hormone-Refractory Prostate Cancer

RATIONALE: A low-fat, high-fiber diet that includes soy protein may prevent disease progression in patients with hormone-refractory prostate cancer. Nutrition counseling may help motivate patients to follow this diet. PURPOSE: Randomized phase I trial to study the effectiveness of behavior-based dietary interventions, such as receiving nutrition counseling, in helping patients who have hormone-refractory prostate cancer follow a low-fat, high-fiber, soy-supplemented diet.

OBJECTIVES: Determine whether a behavior-based dietary intervention can motivate patients with hormone-refractory prostate cancer to adopt and maintain a dietary pattern that includes < 20% of energy from fat, > 25 g of fiber, and 80 g of soy protein powder. Compare bioavailable levels of testosterone in patients treated with a behavior-based dietary intervention vs observation only. Determine whether this dietary intervention decreases or stabilizes a rising serum prostate-specific antigen level in these patients. Determine whether this dietary intervention improves disease-specific survival, mediated by reduced bioavailable levels of testosterone, in these patients. Determine the impact of a positive intervention outcome on androgen receptors in patients treated with this dietary intervention. OUTLINE: This is a randomized, controlled, pilot, multicenter study. Patients are randomized to 1 of 2 treatment arms. All patients receive nutritional counseling on a healthy diet. Patients also keep a food diary during study participation. Arm I (dietary intervention): Patients receive dietary intervention comprising nutritional counseling on a low-fat, high-fiber, soy supplemented diet and behavior-based activities, such as goal-setting, contracting, and stimulus control, once weekly for 6 weeks, every 3 weeks for 33 weeks, and then at weeks 44, 48, and 52. Treatment continues in the absence of disease progression or unacceptable toxicity. Arm II (observation): Patients undergo observation every 6 weeks for 36 weeks and then every 8 weeks for 18 weeks. PROJECTED ACCRUAL: A total of 92 patients (46 per treatment arm) will be accrued for this study.

Nutritional counseling on a low-fat, high-fiber, soy supplemented diet and behavior-based activities, such as goal-setting, contracting, and stimulus control, once weekly for 6 weeks, every 3 weeks for 33 weeks, and then at weeks 44, 48, and 52.

DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the prostate No small cell component No histologically confirmed and/or demonstrable metastatic or locally recurrent disease by bone scan, chest x-ray, computed tomography (CT) scan, or transrectal ultrasound No clinical symptoms within the past 90 days Documented biochemical failure after radical prostatectomy Prostate-specific antigen must have initially nadired to an undetectable level (< 0.1 ng/mL) after prostatectomy AND is currently rising (0.3-40.0 ng/mL) Serum testosterone > 100 ng/dL PATIENT CHARACTERISTICS: Age Any age Performance status Zubrod 0-1 Life expectancy At least 1 year Hematopoietic Not specified Hepatic Not specified Renal Not specified Other No known allergic reactions to milk or soy products PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy More than 1 year since prior chemotherapy Endocrine therapy More than 1 year since prior hormonal therapy Radiotherapy Not specified Surgery See Disease Characteristics