PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent immunotherapy Chemotherapy: See Disease Characteristics No other concurrent chemotherapy Endocrine therapy: See Disease Characteristics Radiotherapy: See Disease Characteristics At least 4 weeks since palliative radiotherapy and recovered No prior radiotherapy to greater than 30% of bone marrow reserve No concurrent radiotherapy Surgery: See Disease Characteristics At least 4 weeks since prior surgery (lesser period acceptable if deemed in best interest of patient) Other: No concurrent metoclopramide or cisapride to maintain motility or gastric emptying At least 30 days or 5 half-lives since other prior investigational drugs for treatment of cancer No other concurrent investigational medication