Green Tea Extract in Treating Patients With Metastatic Prostate Cancer That Has Not Responded to Hormone Therapy

DISEASE CHARACTERISTICS: Clinically proven androgen-independent metastatic prostate cancer Radiological, physically palpable, and/or biochemical evidence of progression Increase in PSA after orchiectomy or hormonal treatment No symptoms directly attributable to metastatic disease No CNS metastases or carcinomatous meningitis PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Not specified Hepatic: Bilirubin no greater than 1.5 mg/dL Renal: Creatinine no greater than 2 times upper limit of normal Cardiovascular: No uncontrolled high blood pressure No unstable angina No symptomatic congestive heart failure No uncontrolled cardiac arrhythmias No myocardial infarction in past 6 months Other: No other malignancy within the past 5 years except basal cell skin cancer No uncontrolled diabetes mellitus or inability to tolerate high sugar content of green tea at discretion of oncologist No other medical or psychiatric conditions that would preclude study PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy Chemotherapy: At least 4 weeks since prior chemotherapy No concurrent chemotherapy Endocrine therapy: At least 4 weeks since prior flutamide or megestrol At least 6 weeks since prior longer-acting hormonal agents such as bicalutamide At least 4 weeks since prior hormonal therapy, except luteinizing hormone- releasing hormone agonist No concurrent hormonal therapy, including corticosteroids for cancer treatment Radiotherapy: No concurrent radiotherapy Surgery: See Disease Characteristics Other: No other concurrent investigational agents