Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed solid tumor that is refractory to conventional therapy or
for which no effective therapy is known

- Brain tumors eligible Brainstem gliomas may waive histological verification
requirement

- Neurologic deficits associated with CNS malignancies must be stable for a minimum of
4 weeks prior to study

- No leukemia Stratum 2

- No marrow involvement

PATIENT CHARACTERISTICS:

- Age: 21 and under

- Performance status: Karnofsky or Lansky 50-100%

- Life expectancy: At least 8 weeks

- Absolute neutrophil count at least 1,000/mm3

- Platelet count at least 75,000/mm3

- Hemoglobin at least 9 g/dL

- Bilirubin less than 1.5 mg/dL

- SGPT less than 5 times normal

- Creatinine normal for age OR creatinine clearance at least 70 mL/min

- Shortening fraction at least 27% of normal OR ejection fraction greater than 50% of
normal

- Not pregnant or nursing

- Negative pregnancy test required

PRIOR CONCURRENT THERAPY:

- No concurrent anticancer therapy

- At least 6 months since bone marrow transplant and no evidence of graft versus host
disease

- At least 1 week since growth factors

- No concurrent granulocyte colony-stimulating factor

- Recovered from prior immunotherapy

- Stratum 2: No prior bone marrow transplantation (with or without total body
irradiation)

- At least 6 weeks since prior nitrosourea

- At least 2 weeks since other prior myelosuppressive chemotherapy

- Dexamethasone must be a stable or decreasing dose for 2 weeks prior to study

- Recovered from prior chemotherapy

- Stratum 2: No more than 2 prior chemotherapy regimens

- At least 2 weeks since local palliative radiotherapy (small port)

- At least 6 months since prior substantial bone marrow radiation (e.g., cross-
sectional radiotherapy [greater than 24 Gy], total body irradiation, hemi- pelvic
radiotherapy)

- Recovered from prior radiotherapy

- Stratum 2: No prior central axis radiation