PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy No concurrent biologic therapy Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy No concurrent chemotherapy Endocrine therapy: At least 2 weeks since prior hormonal therapy Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy Concurrent localized radiotherapy allowed provided measurable disease exists outside of the radiation field Surgery: At least 2 weeks since prior surgery Concurrent localized surgery allowed provided measurable disease exists outside of the surgical field Other: At least 4 weeks since other prior investigational therapy No concurrent medication that decreases renal function (e.g., aminoglycoside antibiotics) No other concurrent investigational agent Concurrent bisphosphonates allowed