First isolated extramedullary relapse in children with B-cell precursor acute lymphoblastic leukaemia: results of the Cooprall-97 study.

We report on the efficiency of treatment of first isolated extramedullary relapse of B-cell precursor acute lymphoblastic leukaemia. Sixty-eight children and adolescents were included in the trial COPRALL-97. Stratification criteria were time to relapse: first complete remission duration of less than 24 months for group G3A (n=35), relapse beyond 24 months for group G3B (n=33). Treatment consisted of risk-adapted alternating short course multiagent systemic and intrathecal chemotherapy and irradiation (18Gy). Event free survival (EFS) and overall survival (OS) for all registered patients at 6 years were 43% and 55%, respectively. EFS at 4 years for patients of group G3A and G3B were, respectively, 31% and 61% (p=0.0071) while OS at 4 years were, respectively, 40% and 76% (p=0.065). Our analyses highlighted two independent risks factors predictive of decreased EFS: early relapse and age at the initial diagnosis above 6 years. Early central nervous system relapses have a bad prognosis, and new therapeutic strategies are needed.