What is the prognosis of pediatric acute lymphoblastic leukemia (ALL)?

Updated: Jan 03, 2019
  • Author: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP; Chief Editor: Jennifer Reikes Willert, MD  more...
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Answer

The likelihood of long-term cure in ALL depends on the clinical and laboratory features and the treatment. Prognostic risk assessment includes clinical features (age and white blood cell [WBC] count at diagnosis), biologic characteristics of the leukemic blasts, response to the induction chemotherapy, and minimal residual disease (MRD) burden. Based on these criteria, patients can be effectively stratified into low risk, average or standard risk, high risk, and very high-risk. [7]

Standard-risk patients are aged 1-9.9 years with WBC of less than 50,000 at presentation, lack unfavorable cytogenetic features, and show a good response to initial chemotherapy. The Children’s Oncology Group (COG) defines standard risk as less than 1% blasts in peripheral blood by 8 days and less than 0.01% blasts in bone marrow by 29 days (rapid early response). Low-risk patients have < 0.01% blasts for both time points and have favorable cytogenetics (eg, trisomy 4, 10). High-risk patients do not meet these criteria or have extramedullary involvement that makes it inappropriate for them to be treated as standard risk. Very-high-risk patients have unfavorable cytogenetic features (Philadelphia chromosome, hypodiploidy (n < 44), MLL gene rearrangement or poor response to initial chemotherapy (induction failure or Day 29 bone marrow with MRD >0.01%).

Patients younger than 1 year with acute leukemia have disease that is biologically distinct with a poor outcome. [8]

The 5-year event-free survival (EFS) varies considerably depending on risk category, from 95% (low risk) to 30-80% (very high risk), with infant leukemia having the worst outcomes: 20% for patients younger than 90 days. COG redefined very high risk to include high risk patients ≥13 years of age, which made the range of outcomes wider for this subgroup. Overall, the cure rate for childhood acute lymphoblastic leukemia (ALL) is more than 80%.

Five-year survival rates for children diagnosed with ALL rose to 90% from 2000-2005, which was up from 84% in 1990-1994. [5] Improvement in survival was observed for all age groups of children, except for infants younger than 1 year. In low-income countries (LIC), therapeutic results for pediatric ALL have been less encouraging due to delayed diagnosis, abandonment of therapy, and death from toxicity due to suboptimal supportive care. Nevertheless, current 4-year event-free survival rates are 61% in India, [8] and over 78% in Lebanon, [9] demonstrating that pediatric ALL is curable in LIC.

An analysis of long-term survival among 21,626 children with ALL treated in COG trials from 1990-2005 found that 10-year survival rose to almost 84% in 1995-1999 from 80% in 1990-1994. The analysis also found that survival improved for almost all groups, including older children and black children. [5]


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