Treatment of acute leukemia in adults

Improvement in the management of acute leukemia in adults has not progressed nearly so rapidly as has the treatment of childhood leukemia. One important difference is that most adults have myeloblastic or related forms of the disease (AML), whereas the majority of children have lymphoblastic leukemia (ALL). However, even adults with ALL fail to respond as well to a similar regimen as do children with the same type of leukemia. In a recent series of patients with ALL who were treated with the complex multiple drug "L-2" protocol, the incidence of complete remission in adults was 78% vs. 99% in children, and the median duration of remission was only 24 months in the adults, whereas it has not yet been reached in the children and is projected to be over 4 years. In AML and the related nonlymphoblastic forms of acute leukemia, therapy is still unsatisfactory in both adults and children. With the best current drug treatment schedules, the incidence of complete remission is now better than 50%, but it is often difficult to compare the exact remission rates in different series because of differences in reporting results. In adults treated with the multiple drug "L-6" protocol, the incidence of remission in previously untreated patients was 56% and the median duration of remission was 10 months. The median survival of all patients (responders and non-responders) was 1 year whereas that of responders only was 2 years. It is encouraging that a significant proportion of those patients with AML who have complete remissions now remain in remission for extended periods; about 45% of patients responding to the "L-6" protocol remained in remission over 1 year, and 18% have been in continuous remission for 2 to over 4 years. Even after discontinuing treatment, some patients with AML stay in remission for long periods, and it is possible that some of them may have been cured. If this proves to be true, it becomes of great importance to determine what is different about the patients who do exceptionally well as compared to the majority who continue to die within a year. However, no consistent nor distinctive favorable prognostic features have yet been identified.