Does the early intensification of intrathecal therapy improve outcomes in pediatric acute lymphoblastic leukemia patients with CNS2/TLP+ status at diagnosis?

OBJECTIVES

We aimed to determine whether the addition of two extra intrathecal methotrexate (ITM) doses during induction in acute lymphoblastic leukemia (ALL) patients eliminate the prognostic significance of CNS2/TLP+ status.

METHODS

We retrospectively analyzed 224 patients according to the central nervous system (CNS) involvement at diagnosis: CNS1, CNS2, or CNS3. Patients with CNS2/TLP+ received two additional ITM doses during induction. Patients were treated according to the Children's Cancer Group (CCG)-1991/1961 protocols between January 2001 and December 2007.

RESULTS

The 5-year relapse-free survival (RFS) rates for the ALL patients in the CNS1, CNS2, and CNS3 groups were 80.4 ± 3.0, 100, and 73.5 ± 11.3%, respectively; a non-significant difference was observed between the groups (P = 0.063). However, the patients with CNS2 had significantly better survival compared with the CNS3 patients (P = 0.03). The 5-year cumulative incidence of relapse (CIR) rates for the three groups were 17 (95% confidence interval (CI): 11.9-22.9), 0, and 18.8% (95% CI: 4.3-41.1), respectively; (P = 0.214) and those of isolated or combined CNS relapse were 9.6 (95% CI: 5.8-14.5), 0 and 6.3% (95% CI: 0.3-25.8), respectively (P = 0.424).

CONCLUSIONS

This study shows that the intensification of ITM therapy during induction improves outcomes in patients with CNS2/TLP+ status and eliminates its prognostic significance. This suggests that early intensification using CNS-directed therapy is beneficial in controlling minimal CNS disease.