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