 - Patients with recurrent or refractory solid tumors, including CNS tumors and lymphoma, are eligible; patients must have had histologic verification of malignancy at original diagnosis or relapse except in patients with intrinsic brain stem tumors, optic pathway gliomas, or patients with pineal tumors and elevations of cerebrospinal fluid CSF or serum tumor markers including alpha-fetoprotein or beta-human chorionic gonadotropin HCG 