Risk-Adjusted Combination Chemotherapy in Treating Young Patients With Acute Lymphoblastic Leukemia

DISEASE CHARACTERISTICS:

• Cytologically proven acute lymphoblastic leukemia (ALL)
• No relapse of a previously unrecognized ALL

• Patients must meet one of the following risk criteria:

  • Standard-risk (SR) group meeting all of the following criteria:

    • Blasts < 1,000/μL in peripheral blood (PB) on day 8
    • Aged 1 to < 6 years
    • Initial WBC < 20,000/μL
    • M1 (5%) or M2 (≥ 5% to < 25%) blasts in bone marrow on day 15
    • M1 marrow on day 33

  • Intermediate-risk (IR) group meeting all of the following criteria:

    • Aged < 1 or ≥ 6 years and/or WBC ≥ 20,000/μL
    • Blasts < 1,000/μL in PB on day 8
    • M1 or M2 marrow on day 15
    • M3 (≥ 25%) marrow on day 15 OR meets SR criteria but M3 marrow on day 15 and M1 marrow on day 33

  • High-risk (HR) group meeting ≥ 1 of the following criteria:

    • Meets IR criteria and M3 marrow on day 15 (not SR and M3 on day 15)
    • Blasts ≥ 1,000/μL in PB on day 8
    • M2 or M3 marrow on day 33
    • Translocation t(9;22) [BCR/ABL+] (Philadelphia chromosome-positive) or t(4;11) [MLL/AF4+]
• No secondary ALL

PATIENT CHARACTERISTICS:

• No Down syndrome
• No other major disease that prohibits study treatment (e.g., severe congenital heart disease)
• Not requiring significant therapy modification owing to study therapy-associated complications
• No complications due to other interventions
• No one with missing data that are needed for the differential diagnosis, or for selection of the proper therapy arm

PRIOR CONCURRENT THERAPY:

• No steroids or cytostatic drugs within four weeks prior to start of study therapy