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Myeloid leukemias that arise in children with Down syndrome, particularly in patients younger than 4 years, are a distinct subset of acute myeloid leukemia (AML) characterized by the co-existence of trisomy 21 and GATA1 variants within the leukemic blasts that are often, but not always, megakaryoblastic.
This distinct leukemia is further subdivided into two types:[
It is important to recognize the possibility of these versions in both children with Down syndrome phenotypes and in those who have mosaic trisomy 21, which can be solely present in the leukemic blasts. If possible, newborns with apparent AML should not begin therapy until genetic testing results have been returned.[
In older children with megakaryocytic AML, it is important to rule out the presence of co-existing trisomy 21 and GATA1 variants. These children may be successfully treated with the lower-intensity chemotherapy regimens that are used for children with myeloid leukemia associated with Down syndrome.[
References:
Cancer in children and adolescents is rare, although the overall incidence has slowly increased since 1975.[
For specific information about supportive care for children and adolescents with cancer, see the summaries on
The American Academy of Pediatrics has outlined guidelines for pediatric cancer centers and their role in the treatment of children and adolescents with cancer.[
References:
Incidence
Approximately 10% of neonates with Down syndrome develop TAM (also termed transient myeloproliferative disorder [TMD]).[
Clinical Presentation and Risk Groups
Although TAM is usually a self-resolving condition, it can be associated with significant morbidity and may be fatal in 10% to 17% of affected infants.[
The following three risk groups have been identified on the basis of the diagnostic clinical findings of hepatomegaly with or without life-threatening symptoms:[
Molecular Features
Genomics of TAM
TAM blasts most commonly have megakaryoblastic differentiation characteristics and distinctive variants involving the GATA1 gene in the presence of trisomy 21.[
GATA1 variants are present in most, if not all, children with Down syndrome who have either TAM or acute megakaryoblastic leukemia (AMKL).[
A 2024 analysis screened 143 TAM samples for additional somatic variants in the abnormal cells. With the exception of rare STAG2 variants, the study found no additional abnormalities beyond the typical GATA1 abnormality.[
Approximately 20% of infants with TAM and Down syndrome eventually develop AML. Most of these cases are diagnosed within the first 3 years of life.[
Treatment of TAM
While observation is appropriate for most infants with TAM, therapeutic intervention is warranted in patients with apparent severe hydrops or organ failure. Because TAM eventually spontaneously remits, treatment is short in duration and primarily aimed at the reduction of leukemic burden and resolution of immediate symptoms. Several treatment approaches have been used, including the following:
Risk Factors for the Development of AML After Resolution of TAM
Subsequent development of myeloid leukemia of Down syndrome (MLDS) is seen in 10% to 30% of children with TAM. It has been reported at a mean age of 16 months (range, 1–30 months).[
The use of cytarabine for TAM symptoms or persistent MRD in TAM has failed to show a reduction in later MLDS, as reported in large observational cohort studies.[
References:
General Information
Children with Down syndrome have a 10-fold to 45-fold increased risk of leukemia when compared with children without Down syndrome.[
Prognosis of Children With MLDS
Outcome is generally favorable for children with Down syndrome who develop AML. This is called myeloid leukemia of Down syndrome (MLDS) in the World Health Organization (WHO) classification.[
Prognostic factors for children with MLDS include the following:
Approximately 29% to 47% of patients with Down syndrome present with myelodysplastic neoplasms (MDS) (<20% blasts) but their outcomes are similar to those with AML.[
Treatment of Newly Diagnosed Childhood MLDS
Appropriate therapy for younger children (aged ≤4 years) with MLDS is less intensive than current standard childhood AML therapy. Hematopoietic stem cell transplant is not indicated in first remission.[
Treatment options for newly diagnosed children with MLDS include the following:
Evidence (chemotherapy):
The following two prognostic factors were identified:[
Children with mosaicism for trisomy 21 are treated similarly to those children with clinically evident Down syndrome.[
Treatment options under clinical evaluation
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the
Treatment of Relapsed or Refractory Childhood MLDS
A small number of trials address outcomes in children with MLDS who relapse after initial therapy or who have refractory MLDS. In three prospective trials of children with newly diagnosed MLDS, outcomes were poor for those who relapsed (4 of 11, 2 of 9, and 2 of 12 patients who relapsed survived).[
Treatment options for children with refractory or relapsed MLDS include the following:
Evidence (treatment of children with refractory or relapsed MLDS):
Four analyses have specifically examined children with relapsed or refractory MLDS.[
References:
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
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Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of childhood myeloid proliferations associated with Down syndrome. It is intended as a resource to inform and assist clinicians in the care of their patients. It does not provide formal guidelines or recommendations for making health care decisions.
Reviewers and Updates
This summary is reviewed regularly and updated as necessary by the
Board members review recently published articles each month to determine whether an article should:
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
The lead reviewers for Childhood Myeloid Proliferations Associated With Down Syndrome Treatment are:
Any comments or questions about the summary content should be submitted to Cancer.gov through the NCI website's
Levels of Evidence
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Pediatric Treatment Editorial Board uses a
Permission to Use This Summary
PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary]."
The preferred citation for this PDQ summary is:
PDQ® Pediatric Treatment Editorial Board. PDQ Childhood Myeloid Proliferations Associated With Down Syndrome Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at:
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Last Revised: 2024-09-16
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