PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 6 weeks since prior nitrosoureas or mitomycin and recovered Endocrine therapy: Concurrent steroid use allowed Radiotherapy: At least 6 weeks since prior radiotherapy (except radiotherapy to small isolated fields not including significant areas of bone marrow) and recovered No prior radiotherapy to tumor site(s) that will be imaged by MRI/PET scanning or used to assess tumor response Surgery: No concurrent open surgery Other: At least 4 weeks since all other prior anticancer therapies and recovered No concurrent heparin or warfarin Concurrent NSAIDs allowed