Summary curves for patients transplanted for chronic myeloid leukaemia salvaged by a donor lymphocyte infusion: the current leukaemia-free survival curve

A significant number of patients who relapse after allogeneic stem cell tra nsplantation (SCT) for chronic myeloid leukaemia (CML) will achieve sustain ed molecular remissions after treatment with donor lymphocyte infusions (DL I) from the original stent cell donor. Leukaemia-free survival, defined as survival without evidence of relapse at any time after transplant does not account for patients who are successfully treated with DLI. To summarize ad equately the response to treatment, a new summary probability, called the c urrent leukaemia-free survival (CLFS), is proposed. This quantity is define d as the probability that a patient is alive and in remission at a given ti me after transplant. We discuss two statistical methods for estimating CLFS . The first is based on a multistate modelling approach. The second is base d on an estimate constructed by looking at appropriate differences between Kaplan-Meier estimates. We compare these estimates using data on 189 consec utive patients who underwent SCT over a 7-year period.