Introduction

About 80% to 90% of children with newly diagnosed acute myeloid leukemia (AML) achieve complete remission (CR) with intensive induction chemotherapy. However, 10% to 20% of patients do not achieve remission due to early death by hemorrhage, leukostasis, infection or resistant disease (primary refractory AML), and even after achieving remission, 30% to 50% of patients still relapse. Primary refractory AML and relapsed AML have a poor prognosis, with an overall survival of less than 25%. For patients in first relapse, the prognosis mainly depends on the time of relapse. If it is early, defined as within 1 to 1.5 years after initial diagnosis, the second CR rate is about 50% and overall survival 10% or less. If the time of relapse is late, defined as later than 1.5 years after diagnosis, the second CR rate is 80% to 90% with an overall survival of up to 40%. Multiple-relapsed AML has an even worse prognosis. The management of refractory or relapsed AML is quite difficult. Several treatment schedules have been studied recently, and progress seems feasible with the use of new drugs and novel drug combinations followed by hematopoietic stem cell transplantation (HSCT).

Definition

Relapse is defined as the reappearance of leukemic cells at any site in the body. Most relapses in AML occur during treatment, mostly during the first year after diagnosis. Relapses after 2 years are rarely seen (Fig. 20.1).