OUTLINE: This is a dose-escalation study. Patients receive oral SarCNU on days 1, 5, and 9. Treatment continues every 4 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of SarCNU until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, additional patients are treated at the MTD.