OUTLINE: This is a dose escalation study of etoposide. Patients receive oral etoposide daily on days 1-10 and oral fluorouracil-uracil plus oral leucovorin calcium twice a day on days 1-21. Treatment repeats every 28 days for a maximum of 6 courses in the absence of unacceptable toxicity or disease progression. Cohorts of 3-6 patients receive escalating doses of etoposide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 or more of 6 patients experience dose-limiting toxicity. Patients are followed at 2 months and then periodically for survival.