DISEASE CHARACTERISTICS:

• Histologically confirmed acute lymphoblastic leukemia (ALL) of FAB L1 or L2 morphology

  • Positive SIg allowed OR

• Histologically confirmed precursor B or precursor T lymphoblastic non-Hodgkin's lymphoma (NHL)

  • No diffuse large cell B-cell lymphoma, Burkitt's lymphoma, or high-grade B-cell lymphoma (Burkitt-like)

• Very low-risk (VLR) patients meeting 1 of the following criteria:

  • ALL of B-cell lineage

    • WBC less than 10,000/mm^3

    • Must meet 1 of the following conditions:

      • DNA index greater than 1.16 and less than 1.50 and chromosome number 51-66 or unknown
      • DNA index not assessed and chromosome number 51-66
      • DNA index greater than 1.16 and less than 1.50 and chromosome number is unknown
    • Good response to prephase therapy
    • Absence of t(9;22) or BCR/ABL, t(4;11)/MLL-AF4, or 11q23/MLL rearrangement
    • No acute undifferentiated leukemia (AUL)
    • No CNS or gonadal involvement
  • Precursor B-lymphoblastic NHL stage I or II OR

• Average risk (AR) patients:

  • Must meet 1 of the following criteria:

    • ALL with good response to prephase therapy who are neither VLR or very high risk (VHR)
    • VLR ALL with CNS involvement (CSF positive or negative)
    • Precursor B-lymphoblastic NHL stage III or IV without any VHR feature
    • Precursor T-lymphoblastic NHL

  • AR patients substratified in:

    • AR1: B-cell lineage ALL with WBC less than 100,000/mm^3

      • Surreptitious or hemorrhagic CSF becoming negative at D4 of prephase therapy
      • Precursor B-lymphoblastic NHL stage III or IV
      • Precursor T-lymphoblastic NHL stage I or II

    • AR2: B-cell lineage ALL with WBC at least 100,000/mm^3

      • T-cell lineage ALL regardless of the WBC
      • Overt or non-equivocal CNS involvement at D0 or any CSF involvement at D4
      • Gonadal involvement
      • Precursor T-lymphoblastic NHL stage III or IV
  • Newborn Down syndrome patients with AR2 features are assigned to the AR1 group OR

• VHR patients:

  • Must meet 1 of the following criteria:

    • ALL patients meeting 1 of the following conditions:

      • Poor response to prephase therapy (at least 1,000/mm^3 blasts in peripheral blood after completion of prephase therapy)
      • t(9;22) or BCR/ABL
      • t(4;11)/MLL-AF4 = 11q23/MLL rearrangement
      • Near haploidy (no more than 34 chromosomes or DNA index less than 0.7)
      • Hypodiploid (35-40 chromosomes or DNA index 0.7 to 0.8)
      • AUL
      • For B lineage ALL: failure to achieve complete response (CR) after completion of protocol IA
      • For T lineage ALL: failure to achieve CR or good partial response (GPR) after completion of protocol IA
      • Minimal-residual disease (greater than 1,000 blasts/100,000 mononuclear bone marrow cells) at evaluation of IA (day 35)
    • NHL patients who failed to achieve CR or GPR after completion of protocol IA

  • All VHR patients are eligible for stem cell transplantation except those whose sole VHR criterion is a poor response to prephase therapy and who have none of the following features:

    • T-cell immunophenotype
    • Early B ALL (CD10 negative)
    • WBC at least 100,000/mm^3
  • Newborn Down syndrome patients with VHR features are assigned to AR1 group NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.

PATIENT CHARACTERISTICS:

Age:

• Under 18

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• See Disease Characteristics

Hepatic:

• Not specified

Renal:

• Not specified

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• See Disease Characteristics

Chemotherapy:

• Not specified

Endocrine therapy:

• Not specified

Radiotherapy:

• Not specified

Surgery:

• Not specified

Other:

• No prior therapy