DISEASE CHARACTERISTICS:

• Newly diagnosed acute lymphoblastic leukemia meeting 1 of the following risk definitions:

  • Standard-risk disease:

    • Age 1 to 9 years
    • WBC < 50/mm^3 OR TEL/AML1-positive disease
    • Good response to prior prednisone (day 8 peripheral blood blast < 1,000/mm^3)

    • None of the following subtypes:

      • T-cell
      • t(9;22)
      • t(4;11)
      • t(1;19)
      • Molecular
    • Bone marrow (BM) M1 or M2 on day 15, BM remission (< 5% blast) on day 33

  • Intermediate-risk disease:

    • Good response to prior prednisone
    • BM M1/M2 on day 15

    • Meets 1 of the following criteria:

      • At least 10 years old
      • WBC > 50/mm^3
      • Under 1 year old without MLL gene rearrangement
      • T-cell OR t(1;19) OR E2A/PBX1
      • Standard-risk patient with BM M3 on day 15
      • If minimal residual disease (MRD) available, day 33 MRD < 10^-2

  • High-risk disease, meeting 1 of the following criteria:

    • Poor response to prior prednisone
    • t(9;22), BCR/ABL, t(4;11), OR MLL/AF4
    • Intermediate-risk patient with BM M3 on day 15
    • BM M2/M3 on day 33
    • If MRD available, flow cytometry/PCR > 10% on days 15 OR MRD > 10^-2 on day 33 OR MRD (before mM or M phase) > 10^-3 on day 84

PATIENT CHARACTERISTICS:

• Not specified

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics