Therapy of acute myelogenous leukemia

Abstract

There has been a rapid improvement in the overall prognosis for patients with acute myelogenous leukemia. The major determinant for this change is a progressive increase in the frequency of inducing complete hematological and clinical remissions from low levels to levels in excess of 50% of patients. The prognostic factors present prior to treatment which predict for a poor probability of response are advanced age, particularly in excess of 60 years, the presence of acute leukemia superimposed on a pre-existing preleukemic syndrome and the association of inevaluable cytogenetic studies. Further improvements in the probability of response requires both the development of better methods of supportive therapy for the host and a better understanding of the treatment of the oligoblastic or unusual leukemic patterns in elderly patients. The duration of remission has not significantly improved for the average patient being somewhere between 10 and 18 months. Analysis of those factors which predict for duration of remission indicate that entirely different variables are involved. Thus, the strategy of treatment for the patient in remission will almost certainly need to be different treatment of the patient with frank disease. Although remission duration has not been significantly prolonged for the average patient, it is observed that an increasing proportion of patients have prolonged remission duration. Careful analysis of duration of remission in patients indicates that the risk of relapse decreases progressively the longer a patient remains in this first remission. In a pilot study, it has been demonstrated that late intensification chemotherapy administered after patients are in remission for a year is associated with an even more favorable remission duration free of disease and free of continued chemotherapy. In this pilot study, there appears to be not only a progressive decrease in the risk of relapse the longer a patient is free of disease but relapse occurring after two years following the late intensification therapy has been very unusual. The small, but progressively increasing proportion of patients with prolonged survival is consistent with the pattern of survival seen in other malignant diseases where we now have convincing evidence of a detectable cure rate. These data support the concept that a small, but detectable, portion of the patients may have been rendered free of their disease. When it is considered that significant improvements in the treatment of acute myelogenous leukemia have only begun within the last 12 years, the rapid rate of change in prognosis for the majority of patients with acute leukemia and the prolonged survivorship observed in a small fraction of the patients provide important grounds for being optimistic about the possibility of long-term control of this disease.