BONE-MARROW TRANSPLANTATION FOR CHRONIC MYELOID-LEUKEMIA - THE EFFECTS OF DIFFERING CRITERIA FOR DEFINING CHRONIC PHASE ON PROBABILITIES OFSURVIVAL AND RELAPSE

We studied actuarial survival and relapse in 251 patients with chronic myeloid leukaemia (CML) treated by bone marrow transplantation (BMT) from HLA-identical sibling donors at a single institution. According t o the institutional criteria used to define disease phase at the time of BMT, the 5-year probabilities of survival were 58.1% (95% confidenc e internal 50-66%) for 205 chronic-phase patients and 21.5% (95%CI 12- 37%) for 46 advanced-phase patients (P<0.00001); the corresponding val ues for relapse were 34.8% (95%CI 27-44%) versus 72.7% (95%CI46-89%). When disease phase was defined strictly according to the criteria of t he International Bone Marrow Transplant Registry, the survival for 154 chronic-phase patients increased to 60.1% (95%CI 51-69%) and that for 97 advanced-phase patients increased to 37.6% (95%CI 28-48%). There w as a parallel change in probabilities of relapse in the two patient gr oups (33.9% [95%CI 25-44%] and 51.3% [95%CI 37-66%], respectively). We also observed that patients transplanted in advanced phase had a high er incidence of grades III-TV acute graft-versus-host disease (P=0.001 ) and transplant-related mortality (P=0.02) than those undergoing BMT for chronic-phase disease. We recommend that transplant centres report ing results of BMT should always specify the precise criteria used for defining disease phase in order to ensure that results between differ ent centres are strictly comparable.