Treatment results in age subgroups by initial white blood cell count (WBC) (ALL-BFM 86 and 90).

A: 10y-probability for event-free survival (pEFS) in patients with initial WBC < 20,000

Log-rank: P < 0.01, except for all comparisons with infant acute lymphoblastic leukemia (ALL) (< 1y); 6–9y vs 15–18y: P = 0.03; 10–14y vs 15–18y: P = n.s.

B: 10y-pEFS in patients with initial WBC ≥ 20,000

Log-rank: P < 0.01 for all comparisons, except for: <1y vs 15–18y: P = 0.04; 6–9y vs. 10–14y or 15–18y: P = n.s.; 10–14y vs 15–18y: P = n.s.