BONE-MARROW TRANSPLANTS FROM HLA-IDENTICAL SIBLINGS AS COMPARED WITH CHEMOTHERAPY FOR CHILDREN WITH ACUTE LYMPHOBLASTIC-LEUKEMIA IN A 2ND REMISSION

Background. It is unclear how best to treat children with acute lympho blastic leukemia who are in a second remission after a bone marrow rel apse. For those with HLA-identical siblings, the question of whether t o perform a bone marrow transplantation or to continue chemotherapy ha s not been answered. Methods. We compared the results of treatment wit h marrow transplants from HLA-identical siblings in 376 children, as r eported to the International Bone Marrow Transplant Registry, with the results of chemotherapy in 540 children treated by the Pediatric Onco logy Group. A preliminary analysis identified variables associated wit h treatment failure in both groups. We selected cohorts by matching th ese variables. A possible bias associated with differences in the inte rval between remission and treatment was controlled for by choosing ma tched pairs in which the duration of the second remission in the chemo therapy recipient was at least as long as the time between the second remission and transplantation in the transplant recipient. A total of 255 matched pairs were studied.Results. The mean (+/- SE) probability of a relapse at five years was significantly lower among the transplan t recipients than among the chemotherapy recipients (45 +/- 4 percent vs. 80 +/- 3 percent, P < 0.001). At five years the probability of leu kemia-free survival was higher after transplantation than after chemot herapy (40 +/- 3 percent vs. 17 +/- 3 percent, P < 0.001). The relativ e benefit of transplantation as compared with chemotherapy was similar in children with prognostic factors indicating a high or low risk of relapse (the duration of the first remission, age, leukocyte count at the time of the diagnosis, and phenotype of the leukemic cells). Concl usions. For children with acute lymphoblastic leukemia in a second rem ission, bone marrow transplants from HLA-identical siblings result in fewer relapses and longer leukemia-free survival than does chemotherap y.