Busulfan in Treating Children and Adolescents With Refractory CNS Cancer

DISEASE CHARACTERISTICS:

Histologically confirmed CNS malignancy, including any of the following:

Primary malignant brain tumor refractory to standard therapy and metastatic to the cerebrospinal fluid (CSF) or leptomeningeal subarachnoid space

Recurrent or persistent leptomeningeal leukemia, lymphoma, or germ cell tumor refractory to conventional therapy

In second or greater relapse
CSF white blood count greater than 5 cells/mm3 with blasts on cytospin OR
Evidence of leptomeningeal tumor by MRI
No concurrent bone marrow disease
No obstruction or compartmentalization of CSF flow on CSF flow study

PATIENT CHARACTERISTICS:

Age:

3 to 21

Performance status:

Lansky 50-100% (under 10 years)
Karnofsky 50-100% (10 to 21 years)

Life expectancy:

Greater than 8 weeks

Hematopoietic:

Absolute neutrophil count greater than 1,000/mm^3
Platelet count greater than 75,000/mm^3

Hepatic:

Bilirubin normal for age
ALT and AST less than 5 times upper limit of normal (ULN)
No hepatic disease

Renal:

Creatinine no greater than 1.5 times ULN OR
Glomerular filtration rate greater than 70 mL/min
No renal disease

Cardiovascular:

No cardiac disease

Pulmonary:

No pulmonary disease

Other:

No uncontrolled infection
Not pregnant or nursing
Negative pregnancy test
Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

Not specified

Chemotherapy:

At least 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosoureas)
At least 1 week since prior intrathecal chemotherapy (2 weeks for cytarabine) and recovered
Evidence of subsequent disease progression

Concurrent systemic chemotherapy allowed for recurrent disease after first course of treatment except for the following:

Chemotherapy targeted at leptomeningeal disease
Other phase I agent
Any agent that significantly penetrates the CSF (e.g., high dose methotrexate greater than 1 g/m2, thiotepa, high dose cytarabine, fluorouracil, IV mercaptopurine, nitrosoureas, or topotecan)
Any agent that causes serious unpredictable CNS side effects

Endocrine therapy:

Prior dexamethasone allowed with decreasing or stable dose at least one week before study
Concurrent dexamethasone or prednisone with chemotherapy regimen allowed

Radiotherapy:

At least 1 week since prior focal irradiation to the brain or spine
At least 8 weeks since prior craniospinal irradiation
No concurrent cranial or craniospinal irradiation

Surgery:

Not specified

Other:

No other concurrent intrathecal or systemic therapy for leptomeningeal disease