Superior prognosis in combined compared to isolated bone marrow relapses in salvage therapy of childhood acute lymphoblastic leukemia.

Three hundred twenty-six children with bone marrow (BM) relapse of non-B acute lymphoblastic leukemia (ALL) were stratified according to the time of relapse in three consecutive multicenter trials--ALL-REZ BFM 83, 85, and 87. Employing an intensive polychemotherapy regimen, extramedullary involvement appeared to be predictive of superior outcome in both strata as well as in the whole group (probability of 7-year event-free survival (EFS) 42% in combined vs. 15% in isolated BM relapse, P = 0.015). Children with combined BM relapse occurring later than 6 months after completion of front-line therapy reached EFS estimates of 60%. We conclude that results of conventional polychemotherapy with BFM relapse protocols are equivalent to those achieved by bone marrow transplantation in children with late combined BM relapse.