Current status of treatment of acute leukemia in adults: An overview of the memorial experience and review of literature

The results of treatment of 629 previously untreated adults with acute leukemia at Memorial Hospital are reviewed. During the past 14 years, 135 adults (>15 years) with acute lymphoblastic leukemia (ALL) have been treated with one of three successive multidrug-intensive treatment protocols (L2, L10/10M, and L17/17M), each calling for 2.5 to 3 years of systemic chemotherapy and prophylactic intrathecal methotrexate without cranial irradiation. The complete remission (CR) rates were 1.2 (n=2.2)=77%; L10/10M (n=69)=86%; L17/17M (n=44)=77%. The median durations of survival and remission were, respectively, L2=33 and 30 months; L10/10M=62 months and not reached; and L17/17M=not reached. Almost all relapses occurrd within the first 3 years while still continuing treatment, and there were only rare late relapses after stopping treatment. It appears that approximately half of the patients may have been cured with the latest two protocols. During the last 17 years, 494 adults aged 15 to >70 with acute nonlymphoblastic leukemia (ANLL) were treated with one of five successive multiple drug treatment protocols of varying intensity (arabinosylcytosine + 6-thioguanine [n=36]; L6 [n=101]; L12 [n=104]; L14/14M [n=121]; and L16/16M [n=132]). Patients with myelodysplastic syndromes generally were not treated until they developed acute leukemia, but were then entered and included in the results. Secondary leukemias following treatment of other neoplastic diseases were not included. The complete remission rates were fairly constant between 47 and 64% and the median durations of remissions were between 9 and 21 months. The intensive treatment L14 and L16 protocols were associated with more early deaths and did not result in a significantly improved remission incidence or duration or survival. With all protocols, the majority of relapses occurred within the first 2 years, but relapses continued to occur at a decreasing rate for 4 years and occasionally even later. Whereas a small fraction (∼10 to 15%) of adults with ANLL are now apparently being cured with combination chemotherapy, despite intensive efforts there has been little improvement during the last decade and more selective and effective forms of treatment are urgently needed.