Prognostic factors and survival outcomes of first CNS relapse in childhood acute lymphoblastic leukemia: results from the ALL-IC REL 2016 study

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.