Does it matter how remission is achieved in acute leukemia?

Patients fail to be cured of acute myeloid leukemia (AML) because they develop absolute or relative resistance to antileukemic drugs such as ara-C (cytarabine) or because they die of complications of bone marrow failure. The Australian Leukemia Study Group (ALSG) has been investigating strategies to improve leukemia control by changing the methods of induction treatment. High-dose ara-C (HIDAC) may overcome ara-C resistance in leukemic blasts, and it has been used as a successful salvage regimen and in postremission therapy. The data from ALSG suggest that a dose-effect relationship exists for ara-C in AML, that the use of HIDAC prolongs remission duration and disease-free survival and that it is tolerable when used as initial induction therapy in patients with de novo AML. A fundamental question still to be answered in ongoing clinical trials is: When should AML treatment be optimally intensified--during the induction phase, immediately after remission, or after 2 to 3 months of preparative regimens, as in some transplantation programs?