Topotecan Hydrochloride in Treating Children With Meningeal Cancer That Has Not Responded to Previous Treatment

Inclusion Criteria: * Histologically proven refractory leukemia, lymphoma, or other solid tumor thathas overt meningeal involvement (Recurrent CNS acute lymphoblastic leukemia stratum only open to accrual as of 11/30/04) * Definition of meningeal disease: * Leukemia/lymphoma (including acute lymphoblastic leukemia) * CSF cell count greater than 5/mm\^3 AND evidence of blast cells oncytospin preparation or by cytology * Refractory to conventional therapy, including radiotherapy (i.e., in second or greater relapse) * No concurrent bone marrow relapse * Solid tumors (including medulloblastoma) * Presence of tumor cells on cytospin preparation or cytology OR presence ofmeningeal disease on MRI scans * No clinical evidence of obstructive hydrocephalus or compartmentalization ofCSF flow as documented by radioisotope indium In 111 or technetium Tc 99 DTPAflow study * If CSF flow block is demonstrated, focal radiotherapy must be administered tosite of block to restore flow and a repeat CSF flow study must show clearing of blockage * No ventriculoperitoneal or ventriculoatrial shunt unless: * Patient is shunt independent and there is evidence that the shunt is nonfunctional * CSF flow study demonstrates normal flow * No impending cord compression, CNS involvement requiring local radiotherapy(e.g., optic nerve), or isolated bulky ventricular or leptomeningeal basedlesions * Performance status - Lansky 50-100% (age 10 and under) * Performan…