Central Nervous System Relapse of Leukemia after Allogeneic Hematopoietic Stem Cell Transplantation

Little information is available regarding central nervous system (CNS) relapse of adult leukemia after allogeneic hematopoietic stem cell transplantation (HSCT). Therefore, we reviewed the data of 1226 patients with acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), and chronic myelogenous leukemia (CML) who received first allogeneic HSCT between 1994 and 2004, using the database of the Kanto Study Group for Cell Therapy (KSGCT), and analyzed the incidence, risk factors, and outcome of patients with CNS relapse. Twenty-nine patients developed CNS relapse at a median of 296 (9-1677) days after HSCT with a cumulative incidence of 2.3%. Independent significant factors associated with CNS relapse included ALL as the underlying diagnosis (relative risk [RR] = 9.55, 95% confidence interval [CI] = 1.26-72.2, P = .029), nonremission at HSCT (RR = 2.30, 95% CI = 1.03-5.15, P = .042), the history of CNS invasion before HSCT (RR = 5.62, 95% CI = 2.62-12.0, P = 9.2 × 10^-6), and the prophylactic intrathecal chemotherapy after HSCT (RR = 2.57, 95% CI = 1.21-5.46, P = .014). The 3-year overall survival (OS) after CNS relapse was 18%. In 7 of 29 patients with CNS relapse, leukemia was observed only in CNS. Three of 7 patients were alive without systemic relapse, resulting in 3-year survival after CNS relapse of 46%. Although the outcome of patients with CNS relapse was generally poor, long-term disease-free survival could be achieved in some patients.