OUTLINE: This is a randomized, open-label, multicenter study. Patients are stratified according to Karnofsky performance status (50-70% vs greater than 70%). Patients are randomized to 1 of 2 treatment arms: Arm I: Patients receive oral nitrocamptothecin on days 1-5. Treatment repeats every week for 8 courses in the absence of disease progression or unacceptable toxicity. Patients with stable or responding disease after week 8 may receive additional courses. Arm II: Patients are stratified according to most appropriate therapy possible (mitomycin or investigator's choice (including best supportive care) vs gemcitabine vs fluorouracil). Patients who previously received fluorouracil and gemcitabine with or without radiotherapy receive mitomycin or the investigator's choice of any proven or experimental chemotherapy regimen previously submitted to the sponsor. Patients who previously received fluorouracil only, other chemotherapy only, or fluorouracil with other chemotherapy receive a proven or experimental regimen comprising gemcitabine. Patients who previously received gemcitabine with other chemotherapy receive a proven or experimental regimen comprising fluorouracil. Patients with stable or responding disease after week 8 may receive additional courses if medically indicated. Patients for whom these drugs are not indicated may receive best supportive care. At the time of disease progression, patients may receive treatment with nitrocamptothecin. Patients are followed every 3 months for 1 year or until death.