OUTLINE: This is a dose escalation study. Patients receive oral carbendazim weekly for 3 weeks followed by 1 week of rest. Treatment is repeated every 28 days in the absence of disease progression or unacceptable toxic effects. Cohorts of 3-6 patients receive escalating doses of carbendazim. If dose limiting toxicity (DLT) is seen in 1 of 3 patients treated at a given dose level, 3 additional patients will be entered at the same dose level. Dose escalation continues until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience DLT. Patients are followed for up to 30 days posttreatment.