Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologic evidence of one of the following malignancies that has failed conventional
therapy:

- Acute lymphoblastic leukemia

- Non-Hodgkin's lymphoma with bone marrow involvement

- Osteogenic sarcoma

- In vitro transport resistance to methotrexate demonstrated by bone marrow aspirate
assay

PATIENT CHARACTERISTICS:

Age:

- 21 and under at diagnosis

Performance status:

- ECOG 0-2

Life expectancy:

- At least 8 weeks

Hematopoietic:

- Granulocytopenia allowed with bone marrow involvement

- Thrombocytopenia allowed with bone marrow involvement

- Anemia allowed with bone marrow involvement

Hepatic:

- (unless due to disease)

- Bilirubin no greater than 2.0 mg/dL

- AST no greater than 100

Renal:

- Creatinine less than 1.5 mg/dL OR

- Creatinine clearance at least 60 mL/min

Other:

- No other serious medical illness

- Not pregnant or nursing

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Prior bone marrow transplantation allowed

Chemotherapy:

- At least 1 week since prior intrathecal treatment

- At least 2 weeks since prior systemic chemotherapy and recovered

- At least 10 days for rapidly proliferating leukemia (i.e., WBC greater than
50,000)

- No concurrent chemotherapy

Endocrine therapy:

- Not specified

Radiotherapy:

- Prior radiotherapy allowed and recovered

- No concurrent radiotherapy

Surgery:

- Not specified