LAUSR

Relapse continues to be the primary cause of death after allogeneic hematopoietic cell transplantation (allo-HCT) in patients with AML. Our current sophisticated molecular and genomic techniques have enabled us to deeply explore the clearance, persistence and reappearance of leukemia at various levels ranging from individual mutations to morphologically apparent blasts.1 With the growing trends in national and international database research, it is of paramount importance to have clear definitions and a uniform consensus in reporting relapse. Without these in place, large-scale database research would not be fully reliable. The goal of this brief piece is to provide specific recommendations on how to report post-HCT relapse in AML. The post-HCT setting is unique because patients are typically monitored more closely and undergo more testing (routinely or to rule out relapse), thus generating a wider array of data potentially relevant to relapse. In addition, interventions such as withdrawal of immunosuppression and donor lymphocyte infusion are specific to HCT. It is critical to have definitions of relapse post HCT tailored for unique characteristics of HCT. We propose the following categories to clarify the definitions of relapse post HCT (Table 1).