Radiation Therapy and Chemotherapy in Treating Children With CNS Relapse From Acute Lymphoblastic Leukemia

DISEASE CHARACTERISTICS:

* Acute lymphoblastic leukemia in first bone marrow remission (M1) with first isolated initial CNS relapse
* More than 5 WBC/microliter in cerebrospinal fluid (CSF) with blasts on cytospin OR immunophenotypic proof (encouraged) of relapse in CSF
* Identifiable blasts and presence on 2 CSF samples 3 weeks apart
* If B-cell terminal deoxynucleotidyl transferase (TdT) OR CD-10
* If T-cell TdT alone OR with CD-7

PATIENT CHARACTERISTICS:

* Age: Over 6 months and under 21 years at relapse
* Patients receiving sustained release cytarabine
* Performance status: Older than 10 years
* Karnofsky greater than 50% Less than 10 years
* Lansky greater than 50%
* Platelet count greater than 40,000/mm3
* Bilirubin less than 2.0 mg/dL
* SGPT less than 5 times normal
* Creatinine less than 1.5 times normal for age
* Normal metabolic parameters (serum electrolytes, calcium, and phosphorus)
* No clinical evidence of obstructive hydrocephalus, compartmentalization of the CSF flow, ventriculoperitoneal or ventriculoatrial shunt

PRIOR CONCURRENT THERAPY:

* Prior cumulative anthracycline dose less than 375 mg/sqm
* Patients receiving sustained release cytarabine
* At least 7 days since prior investigational drug
* At least 3 weeks since prior CNS directed therapy (6 weeks is prior nitrosourea)
* At least 1 week since intrathecal chemotherapy
* At least 8 weeks since prior craniospinal radiotherapy