Can busulfan replace fractionated total body irradiation as conditioning regimen for allogeneic bone marrow transplantation in children with acute lymphoblastic leukemia.

The results of allogenic bone marrow transplantation (allo-BMT) in 26 children with ALL treated with the same initial- and relapse-BFM-protocols, but transplanted in different centers (Poznań, Wroclaw, Hannover) after conditioning with two different regimens have been compared. Ten children (6 in Poznań, 4 in Wroclaw) were conditioned for BMT with busulfan and cyclophosphamide when fractionated TBI (FTBI) was not available there. Sixteen children obtained FTBI and etoposide (11 in Hannover, where in children with ALL exclusively chemoradioconditioning regimen has been employed, and 5 in Poznań). It has been found, that the chemoconditioning procedure was probably less effective (5-year EFS 18%) than the regimen with FTBI (7-year EFS 60%). Therefore, TBI seems to be at this point still mandatory in pediatric ALL patients, unless combinations of chemotherapeutic drugs might be able to substitute the radiation in the future.