Mitoxantrone, Etoposide, and Vinorelbine As Second-Line Therapy in Treating Patients With Metastatic Prostate Cancer That Did Not Respond to Hormone Therapy

RATIONALE: Drugs used in chemotherapy, such as mitoxantrone, etoposide, and vinorelbine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. It is not yet known which drug is more effective in killing tumor cells. PURPOSE: This randomized phase II trial is studying how well mitoxantrone works compared to etoposide or vinorelbine works as second-line therapy in treating patients with metastatic prostate cancer that did not respond to hormone therapy.