Long-Term Prognosis in 139 Children with Acute Lymphoblastic Leukemia Who had been in Complete Remission for Longer than Three Years

—Study of Children's Cancer and Leukemia Study Group—

Abstract

Long-term prognosis was investigated in 139 children with acute lymphoblastic leukemia (ALL) who had been in complete remission for longer than three years.
Thirty five of these children (25.2%) relapsed three years later, and the relapse-free survival (RFS) was estimated 68.5% at 10 years by Kaplan-Meier method. Sites of relapse were bone marrow (BM) in 21, central nervous system (CNS) in 9, testis in 3, and BM and CNS, simultaneously in 2. Twenty five of 35 relapse (71%) occurred during the first year after the three years complete remission. There was no relapse beyond seven years after the onset.
Age or white blood cell counts which is the major prognostic factor at the time of diagnosis, was of no value in predicting the late relapse. However, boys or children with low initial platelet counts (<100,000/mm³), had significantly poorer long-term RFS.
The late relapse was more frequently occurred in the patients treated with 721 Studies consisting of only three intrathecal injection of MTX for CNS prophylaxis and relatively small doses of MTX and 6-MP for maintenance therapy. Prolongation of treatment after three years was no benefit to prevent the late relapse (RFS 53.9% for 3-year treatment, 53.4% for 4-year, 61.2% for 5-year).
These data suggested that early cytoreductive treatment with three or more drugs should be employed for all patients at least within three years. Further studies are necessary to evaluate duration of therapy, especially for boys.