 Patients receive high-dose methotrexate IV over 4 hours on days 1 and 8 and oral trimetrexate glucuronate twice daily on days 2-6 and 9-13. Patients also receive leucovorin calcium IV continuously over 24 hours or orally 2 or 4 times daily on days 9-14. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. 