What is the clinical evidence from this study?

Study design: Cohort. Population: Acute lymphoblastic leukaemia (n=838). Intervention: CNS involvement at diagnosis vs. No CNS involvement at diagnosis. Primary outcome: CNS relapse in B-cell ALL (HR 4.52, 95% CI 1.35-15.2).

What does this research mean for the field?

In adult acute lymphoblastic leukaemia, central nervous system involvement at diagnosis significantly increases the risk of CNS relapse in B-cell ALL but not T-cell ALL, while overall CNS relapse is independently associated with male sex and high white blood cell counts. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

June 3, 2026Open Access

Central nervous system involvement and relapse in adult acute lymphoblastic leukaemia—a population‐based analysis in 2007–2022

Key Result

CNS involvement at diagnosis significantly increased the rate of CNS relapse in adult patients with B-cell acute lymphoblastic leukaemia (HR 4.52; 95% CI 1.35-15.2).

Key Points

The aim is to evaluate the factors associated with central nervous system involvement and relapse in adult acute lymphoblastic leukaemia patients in Sweden from 2007-2022.
Analyzed data from 838 adult ALL patients in Sweden between 2007 and 2022.
Evaluated association between CNS involvement and relapse with factors like white blood cell count and sex.
Calculated 5-year cumulative incidence for CNS relapse and overall survival rates.
CNS involvement at diagnosis was found in 7.8% of patients, mainly in T-cell ALL with WBC count >30 × 10⁹/L.
5-year cumulative incidence of CNS relapse was 4.6% and linked to WBC count >100 × 10⁹/L and male sex.
Patients with CNS relapse had a 2-year overall survival rate of 34%, dropping to 13% if relapse occurred within 12 months.

Study Design

Type

Cohort (n=838)

Multicenter

Yes

Structured PICO

Population

838 adult patients with acute lymphoblastic leukaemia from a Swedish population-based register between 2007 and 2022, evaluated for CNS involvement and relapse.

Outcome

Central nervous system (CNS) involvement at diagnosis and CNS relapsehard clinical

Contemporary treatment protocols prevent CNS relapse for most adult ALL patients, but B-ALL patients with CNS involvement at diagnosis have a high rate of CNS relapse and may require improved CNS-directed therapy.

Main Result

Hazard Ratio: 4.52 (95% CI 1.35–15.2)

Abstract

Summary Central nervous system (CNS) involvement and relapse remains a clinical challenge in the management of acute lymphoblastic leukaemia (ALL), and studies among adult ALL patients are scarce. We identified all adult ALL patients in Sweden between 2007 and 2022 ( n = 838) from the population‐based ALL register and evaluated factors associated with CNS involvement and relapse. CNS involvement at diagnosis was detected in 7.8% of patients, more often in patients with T‐cell ALL (T‐ALL) and with white blood cell (WBC) count >30 × 10 9 /L, without affecting overall survival or risk of any relapse. The 5‐year cumulative incidence of CNS relapse was 4.6% (95% confidence interval CI 3.1–6.6), with WBC count >100 × 10 9 /L and male sex as independent risk factors. Furthermore, CNS involvement at diagnosis increased the rate of CNS relapse in B‐cell ALL (B‐ALL) (hazard ratio HR 4.52, 95% CI 1.35–15.2), but not T‐ALL (HR 0.94, 95% CI 0.12–7.53). Neither Philadelphia chromosome status nor KMT2A::AFF1 was associated with CNS involvement at diagnosis or CNS relapse. Patients with CNS relapse had a 2‐year overall survival of 34% (13% if relapse occurred <12 months from diagnosis). We conclude that contemporary treatment protocols can prevent CNS relapse for most patients but suggest that B‐ALL patients with CNS involvement may have an unmet need for improved CNS‐directed therapy.