Purpose: To assess the effect of treatment intensification and that of extended intrathecal methotrexate substitution for cranial irradiation in intermediate-risk acute lymphoblastic leukemia (ALL) children treated with a Berlin-Frankfurt-Münster (BFM)-based intensive chemotherapy.
Patients: Three hundred ninety-six children with non-B-ALL were enrolled onto the Associazione Italiana di Ematologia ed Oncologic Pediatrica (AIEOP) ALL 88 study. Standard risk (SR) included patients with low tumor burden (BFM risk index [RI], < 0.8); intermediate risk (IR) were patients with an RI > or = 0.8 but less than 1.2; and high risk (HR) were those with an RI > or = 1.2 or CNS involvement at diagnosis. The treatment schedule was a modified version of the ALL-BFM 86 study. CNS-directed treatment consisted of high-dose methotrexate (HD-MTX; 5 g/m2 for four courses) plus intrathecal methotrexate (IT-MTX; nine doses); IR patients additionally received extended IT-MTX (nine doses during continuation therapy); cranial irradiation was given only to HR patients.
Results: Of the 375 (94.7%) children who achieved remission, 1.3% had an adverse event other than relapse. The estimated event-free survival (EFS) at 6 years was 66.6% (SE 2.4) overall; 80.7% (4.5) in the SR patients, 77.5% (3.9) in the IR patients, and 54.5% (3.7) in the HR patients. Relapse occurred in 107 children (27.0%). Isolated CNS relapse occurred in 20 children (5.0%): 5 (6.3%) in the SR group, 1 (0.8%) in the IR group, and 14 (7.1%) in the HR group. The estimated 6-year CNS leukemia-free survival was 94.6% (1.2) overall: 93.5% (2.8) in the SR group, 99.1% (0.9) in the IR group, and 92.3% (2.0) in the HR group.
Conclusion: Cranial irradiation may be omitted safely in IR ALL patients treated with BFM-based intensive chemotherapy when extended intrathecal chemotherapy is given. Because the CNS disease control was less complete in the SR group, these data challenge the effectiveness of HD-MTX for protection from CNS disease and support the protective role of extended intrathecal chemotherapy.