• Toxicity [ Designated as safety issue: Yes ]
• Decrease in prostate-specific antigen-positive cells [ Designated as safety issue: No ]
• Quality of life [ Designated as safety issue: No ]

• Toxicity
• Decrease in prostate-specific antigen-positive cells
• Quality of life

RATIONALE: Genistein may stop the growth of cancer cells by blocking the enzymes necessary for cancer cell growth.

PURPOSE: Phase II trial to study the effectiveness of genistein in treating patients with localized prostate cancer who are planning to undergo radical prostatectomy.

OBJECTIVES:

• Determine the toxicity of genistein in patients with localized prostate cancer treated with radical prostatectomy.
• Determine the decrease, if any, of prostate-specific antigen-positive cells in the operative field of patients treated with this drug.
• Determine the quality of life of patients treated with this drug.

OUTLINE: Patients receive 1 of 2 treatment regimens.

• Group A: Patients receive oral genistein once daily for 1-2 months, undergo radical prostatectomy, and then continue oral genistein once daily for 1-2 months afterward (for a total of 3 months of therapy).
• Group B: Patients undergo radical prostatectomy. Beginning 1 month after surgery, patients receive genistein as in arm I for 3 months.

Quality of life is assessed at baseline and at 1 and 3 months after surgery.

Patients are followed every 3 months.

PROJECTED ACCRUAL: A total of 88 patients (44 patients per treatment group) will be accrued for this study within 2 years.

• Dietary Supplement: genistein
• Procedure: conventional surgery

• Experimental: Patients receive oral genistein once daily for 1-2 months, undergo radical prostatectomy, and then continue oral genistein once daily for 1-2 months afterward (for a total of 3 months of therapy).
• Experimental: Patients undergo radical prostatectomy. Beginning 1 month after surgery, patients receive genistein as in arm I for 3 months.

DISEASE CHARACTERISTICS:

• Diagnosis of localized prostate cancer

  • Diagnosed within the past 6 months
  • T1 or T2 disease
  • Gleason score 5-8
  • Prostate-specific antigen no greater than 20 ng/mL
• Radical prostatectomy planned

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-1

Life expectancy

• More than 2 years

Hematopoietic

• Hemoglobin greater than 9.0 g/dL
• Platelet count greater than 100,000/mm^3
• Absolute neutrophil count greater than 1,000/mm^3

Hepatic

• SGPT and SGOT less than 3 times normal
• Bilirubin less than 3 mg/dL (less than 1.5 times normal) (patients with an elevated bilirubin due to a familial defect in bilirubin metabolism will be considered on an individual basis)

Renal

• Creatinine less than 2.0 mg/dL

Cardiovascular

• No venous thrombosis within the past year

Other

• Patients must use effective barrier contraception
• No other medical condition that would preclude study therapy
• No known soy intolerance

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• Not specified

Endocrine therapy

• No concurrent hormonal therapy for prostate cancer

Radiotherapy

• Not specified

Surgery

• See Disease Characteristics

Other

• No concurrent soy supplements
• No concurrent foods high in genistein
• No concurrent active therapy for neoplastic disorders