Combination Chemotherapy in Treating Patients With Metastatic Prostate Cancer That Has Not Responded to Hormone Therapy

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed stage IV hormone refractory adenocarcinoma of the prostate Progressive disease despite hormonal therapy or orchiectomy No brain metastases PATIENT CHARACTERISTICS: Age: 18 to 80 Performance status: WHO 0-2 Life expectancy: At least 3 months Hematopoietic: Absolute neutrophil count at least 2,000/mm^3 Platelet count greater than 100,000/mm^3 Hemoglobin greater than 9 g/dL Hepatic: Alkaline phosphatase no greater than 2 times upper limit of normal (ULN) (unless bone metastasis) Bilirubin less than 2 times ULN Renal: Creatinine less than 2 times ULN Cardiovascular: Adequate cardiac function Other: No other prior malignancy except curatively treated basal or squamous cell skin cancer or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: See Disease Characteristics Prior corticosteroids allowed if started at least 8 weeks prior to study Radiotherapy: At least 8 weeks since prior extensive radiotherapy Surgery: See Disease Characteristics