Intensive chemotherapy and bone marrow transplantation for children with acute myeloid leukemia

In a recent article, Woods et al detail the findings of a well-designed Children's Cancer Group study comparing matched sibling allogeneic bone marrow transplantation (BMT), autologous bone marrow transplantation, and intensive chemotherapy for children with acute myeloid leukemia (AML) in first complete remission (CR).1The authors drew 2 conclusions that are subject to debate. First, referring to beneficial effect of intensively timed induction therapy, they state that “for the first time in North America we have demonstrated a therapeutic approach to children and adolescents with AML that leads to cure half of the time, … irrespective of the presence of a … family donor.” ^1(p61) It is true that the presented event-free survival estimates for both the allogeneic BMT and chemotherapy groups receiving intensively timed induction therapy exceeded 50% (66% and 53%, respectively); this statement is misleading, however, because this analysis includes only children successfully completing induction therapy and in remission (652 of 887). As the authors themselves point out, the overall survival rate from diagnosis for all patients (allogeneic BMT, autologous BMT, and chemotherapy only) receiving intensively timed induction chemotherapy was only 49%.

The authors, citing the superior overall survival rate for children receiving matched related allogeneic BMT (allogeneic, 60%; chemotherapy, 53%; autologous BMT, 48%), conclude that “for younger patients, including children and adolescents, allogeneic BMT for AML in first remission is the treatment of choice when a matched related donor is available.”^1(p60-61) The authors imply that, for pediatric patients with a matched related donor, a strategy employing allogeneic transplantation in first remission is more effective than a strategy reserving transplantation for the treatment of relapses. The study's design does not permit such a conclusion to be drawn, since all patients with a matched related donor were assigned to a transplant in first remission. By definition, the only potential allogeneic transplant options available to patients in the other 2 groups in the event of a relapse were alternative donor transplants. A randomized controlled study comparing conventional chemotherapy with allogeneic transplantation involving only subjects with matched related donors would be necessary to definitively answer this question. Understandably, this would be much more difficult to conduct.