Role of cranial radiotherapy for childhood T-cell acute lymphoblastic leukemia with high WBC count and good response to prednisone. Associazione Italiana Ematologia Oncologia Pediatrica and the Berlin-Frankfurt-Münster groups.

Purpose: The ALL-BFM 90 and AIEOP-ALL 91 studies share the same treatment backbone and have 5-year event-free survival (EFS) rates close to 75%. This study evaluated the impact of differing presymptomatic CNS therapies in T-cell acute lymphoblastic leukemia (T-ALL) patients with a good response to prednisone (PGR) according to WBC count and Berlin-Frankfurt-Münster (BFM) risk factor (RF).
Patients: A total of 192 patients (141 boys; median age, 7.5 years) with T-ALL, PGR, RF less than 1.7, and no CNS leukemia diagnosed between 1990 and 1995 were enrolled onto the ALL-BFM 90 (n = 123) or AIEOP-ALL 91 (n = 69) study. Presymptomatic CNS therapy consisted of cranial radiation (CRT) and intrathecal methotrexate (I.T. MTX) (11 doses) in the BFM study and of extended triple intrathecal therapy (T.I.T.) (17 doses) in the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) study. Patients were divided into a low-WBC group (WBC count < 100,000/microL) and a high-WBC group (WBC count > 100,000/microL). EFS was compared using the log-rank test.
Results: For patients treated with CRT and I.T. MTX (BFM group), the 3-year EFS rate was 89.8% (SE = 3.5) for 99 patients in the low-WBC group versus 81.9% (SE = 8.2) in the high-WBC group (difference not significant). Conversely, for patients treated with T.I.T. alone (AIEOP group), the EFS rate was 80.6% (SE = 5.6) in 55 patients with a low WBC count versus 17.9% (SE = 11.0) in 14 patients with a high WBC count (P < .001).
Conclusion: These data suggest that CRT may not be necessary in PGR T-ALL patients with a WBC count less than 100,000/microL; on the contrary, in patients with a high count, extended T.I.T. may be inferior to CRT and I.T. MTX.