Delayed central nervous system (CNS) radiation in childhood CNS acute lymphoblastic leukemia. Results of a pilot trial

Abstract

With the introduction of effective prophylactic central nervous system (CNS) therapy in childhood acute lymphoblastic leukemia (ALL), the incidence of CNS relapse has been significantly reduced. Nonetheless, there is a continuing need for effective CNS therapy for the 5% to 10% of children who escape prophylaxis and in whom active CNS disease develops. In July 1985, a pilot study was initiated whereby the consolidative CNS treatment, given in the form of craniospinal axis radiation, was delayed and administered after delivery of a prolonged course of intensive systemic and CNS chemotherapy. Ten leukemic patients with CNS relapse were treated according to this pilot study. One patient did not respond to pre-CNS consolidative therapy and died at 2 months with progressive disease. The remaining nine patients have completed the craniospinal axis radiation. Five patients are off all therapy and remain in remission at a median time of 38 months (range, 31 to 46 months). Two patients are near completion of therapy and are disease-free at 22 and 24 months. Testicular relapse occurred in two patients at 14 and 29 months. CNS chemotherapy, as used in this trial, appears to have allowed for a delay in the administration of the consolidative craniospinal radiation without negatively affecting the CNS remission rate or duration. In turn, this delay has allowed for the uncompromised delivery of intensive multiagent systemic chemotherapy, as well as the separation of those patients destined to early systemic relapse from those who will achieve a sustained complete remission. In both cases, a reduction in the need for multiple courses of potentially toxic CNS therapy as a result of CNS reseeding after radiation is anticipated.