Patients receive oral nitrocamptothecin daily for 5 consecutive days each week for 3 weeks. Treatment continues every 3 weeks for a minimum of 2 courses in the absence of disease progression or unacceptable toxicity. Patients who achieve stable disease (SD) receive up to 4 additional courses past SD. Patients who achieve partial response (PR) or complete response (CR) receive a minimum of 2 additional courses past CR or PR.