Extramedullary relapse after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia is a contributor to post-transplant mortality but risk factors for, and outcomes

©F rr ta St ort i F o nd ati o phylaxis. Extramedullary relapse was biopsy-confirmed in all but one patient, who had obvious progression of proven chloromas that were still present at the time of HSCT. Twenty-four of 26 patients (92%) who had extramedullary disease noted at the time of post-HSCT relapse had bone marrow biopsies confirming the presence (n=2) or absence (n=22) of bone marrow recurrence; the remaining two patients deferred bone marrow evaluation and pursued non-curative supportive care. Statistical analysis Overall rates of relapse, as well as rates of isolated bone marrow and extramedullary relapse, were estimated using the cumulative incidence methods of Gray, treating death as a competing risk, and the association of patients’ characteristics (except for acute and chronic GVHD) with overall and extramedullary relapse was assessed with the competing risk regression methods of Fine and Gray. The association of acute and chronic GVHD, both of which are time-varying covariates, with both types of relapse was assessed using Cox regression methods. A comprehensive multivariate analysis of risk factors for relapse was not possible due to the number of patients available, thus hazard ratios for relapse are those for univariate analyses.