Acute leukemia is the most common form of cancer in children, comprising approximately 30 percent of all childhood malignancies . Of the acute leukemias, acute lymphoblastic leukemia (ALL) occurs five times more commonly than does acute myeloid leukemia (AML). Survival rates for ALL have improved dramatically since the 1980s, with a current five-year overall survival rates estimated at greater than 85 percent [1-4]. This improvement in survival is due to treatment of a large number of children on sequential standardized research protocols. Approximately 75 to 80 percent of children with newly diagnosed ALL participate in such trials, the goals of which are to improve clinical outcomes while minimizing acute toxicities and late-occurring adverse events.
The outcome of ALL in children is reviewed here. Presentation, classification, risk group stratification, and treatment of childhood ALL are discussed separately. (See "Overview of the presentation and classification of acute lymphoblastic leukemia in children" and "Risk group stratification and prognosis for acute lymphoblastic leukemia in children" and "Overview of the treatment of acute lymphoblastic leukemia in children".)
Event free survival — Event-free survival (EFS) rates for ALL have steadily improved since the 1980s [5-7]. The overall five-year EFS for childhood ALL currently approaches 80 percent in the developed world, and the 10-year EFS is about 60 percent . The five- and estimated 10-year survival rates for patients diagnosed from 2000 to 2004 were 88 and 84 percent, respectively . The 10-year survival rate for children diagnosed in the 2005 to 2009 period is estimated to be 88 percent.
In contrast, in the developing world, cure rates are less than 35 percent , in part because of abandonment of treatment  and/or lack of dedicated, multidisciplinary pediatric oncology units . Individual prognosis in the developed world varies according to risk group:
- Five-year EFS rates are highest (>90 percent) for patients with low- or standard-risk B-precursor ALL who have a good response to induction chemotherapy [11-17].
- Patients with high-risk features at presentation and a good early response to induction chemotherapy have a >80 percent five-year EFS with intensive chemotherapy [11-17].
- A subset of very-high-risk patients, such as those with hypodiploid karyotype (less than 44 chromosomes) or slow response to induction chemotherapy, have a poor prognosis, with expected five-year EFS of less than 45 percent [18-20].
- Children with T cell ALL have variable outcomes. Those without high-risk features do relatively well. However, the majority (70 percent in one study ) have high-risk features at presentation (eg, unfavorable age or high WBC count). In one study of 694 children with ALL, overall six-year EFS among the 371 patients with T cell ALL was 62 percent .
- The outcome for children with mature B cell ALL has improved over the past several years. In one study, seven-year EFS for 151 patients with Burkitt-type lymphomas, including mature B cell ALL, was 81 percent. Patients with mature B cell ALL were treated using highly aggressive B cell lymphoma treatment protocols . Patients with B cell ALL who relapse tend to have early recurrences. (See "Risk group stratification and prognosis for acute lymphoblastic leukemia in children", section on 'Mature B cell ALL'.)
- The outcome for children with Philadelphia chromosome (Ph+) ALL has had a significant increase in EFS with the introduction of imatinib . One study of 65 patients with Ph+ ALL reported the addition of imatinib to an intensive chemotherapy resulted in an increase in three-year FS from 35 to 80 percent.
- The prognosis for infant ALL is poor, with an EFS of 10 to 30 percent [25,26]. Aggressive treatment protocols have resulted in improved outcome in some studies [27-30]. The outcome for infants less than 90 days at diagnosis who have the t(4;11) MLL translocation is substantially worse than for older infants without this translocation [31,32].