Central Nervous System Relapse After Stem Cell Transplantation in Adolescents and Young Adults with Acute Lymphoblastic Leukemia: A Single-Institution Experience

Purpose: To evaluate outcomes and central nervous system (CNS) relapse in adolescents and young adults (AYAs) with acute lymphoblastic leukemia (ALL), who underwent total body irradiation (TBI) before allogeneic hematopoietic stem cell transplantation (allo-SCT). Methods: A total of 136 AYA patients with ALL who received TBI before allo-SCT between 1998 and 2018 were reviewed. Twenty patients received cranial radiation in their initial treatment before conditioning for transplant and were excluded. Competing risk analysis was used to estimate the cumulative incidence of relapse. Kaplan-Meier and log-rank tests were used to calculate overall survival (OS) and to identify factors predictive of relapse. OS and time to relapse were calculated from date of allo-SCT. Results: One hundred sixteen patients were included in the analysis. Median age was 27 years and median follow-up time was 42 months. Twenty-six patients suffered a disease relapse and 49 died, 26 of posttransplantation complications. The median time to relapse was 7 months and the 5-year OS was 60%. Seven patients had a CNS relapse: 4 of 20 patients (25%) with pre-SCT CNS disease had a post-allo-SCT CNS relapse compared to 3 of 97 (3.1%) without pre-SCT CNS disease. Median time to CNS relapse was 7 months. Patients with post-SCT CNS relapse had median OS of 19 months. Conclusions: AYA patients with CNS disease who undergo an allo-SCT have a high rate of CNS relapse. The addition of additional CNS-directed therapy to transplant protocols warrants further investigation.