Prognostic factors and survival outcomes of first CNS relapse in childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is among the most curable pediatric cancers, yet relapse involving the central nervous system (CNS) remains a major therapeutic obstacle. In this prospective cohort, 97 children (aged 1.1–18.2 years) experiencing their first CNS relapse were enrolled in the ALL-IC REL study. Relapses were classified as isolated CNS (i-CNS, n = 43) or combined CNS (c-CNS, n = 54), and patients received treatment through standard- or high-risk regimens, encompassing chemotherapy, cranial irradiation, and allogeneic stem cell transplantation. The estimated 2-year event-free survival was 40.0%, and overall survival 49.4%, closely matching outcomes reported internationally. Survival rates were comparable across i-CNS and c-CNS relapses, while induction failure occurred more frequently in c-CNS. Multivariable analysis identified female sex, T-cell phenotype, and very early relapse as independent predictors of poor prognosis. These results underscore the critical necessity for risk-adapted therapy techniques and the incorporation of innovative medicines into forthcoming procedures.