Patients receive gemcitabine IV over 30 minutes weekly for 2 weeks. Patients achieving objective response or stable disease after 3 weeks may receive additional courses of therapy every 3 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of gemcitabine until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose limiting toxicity. Patients are followed at week 4 and then every 6 months until death.