Understanding Pediatric Leukemia: Types, Treatment and the Research Behind Better Outcomes

Leukemia is the most common cancer in children, accounting for roughly 28% of childhood cancers in the United States. Each year, about 3,000 children and adolescents are diagnosed with leukemia.

But “leukemia” isn’t one single disease. There are different types and subtypes, each with distinct biological characteristics, treatment approaches and challenges. Understanding those differences is an important part of understanding the research being done to improve outcomes for children with leukemia.

What is pediatric leukemia?

Leukemia is a cancer of the blood-forming tissues, primarily the bone marrow—the spongy tissue inside our bones where blood cells are produced.

In leukemia, abnormal immature blood cells multiply uncontrollably in the bone marrow. As these leukemia cells accumulate, they crowd out healthy blood-forming cells. This can interfere with the body’s ability to produce normal red blood cells, infection-fighting white blood cells and platelets.

That disruption helps explain many of the symptoms associated with leukemia, including fatigue, frequent infections, fever, easy bruising or bleeding, and bone or joint pain.

What types of leukemia affect children?

The two most common types of childhood leukemia are acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).

Acute lymphoblastic leukemia (ALL)

ALL accounts for approximately 75–80% of childhood leukemia cases. It develops from immature lymphocytes, a type of white blood cell involved in the immune system.

ALL is most commonly diagnosed between the ages of 2 and 5. Although treatment for ALL has become highly successful for many children, researchers continue to study why some children respond differently to treatment, why some experience relapse, and how treatment can be made safer while maintaining or improving its effectiveness.

Acute myeloid leukemia (AML)

AML accounts for approximately 15–20% of childhood leukemia cases. It develops from immature myeloid cells, which normally develop into several types of blood cells.

AML is generally more difficult to treat than ALL and can require more intensive therapy. Researchers continue to investigate the biological differences among AML subtypes and ways to develop more precise treatments.

Rarer forms

Other types of leukemia can also occur in children, including juvenile myelomonocytic leukemia (JMML) and chronic myeloid leukemia (CML). These diseases are uncommon in children and have distinct biological and treatment characteristics.

What causes childhood leukemia?

In most children with leukemia, there is no clear explanation for why the disease developed.

Certain genetic conditions, including Down syndrome, Li-Fraumeni syndrome and neurofibromatosis, are associated with an increased risk of leukemia. Previous chemotherapy or radiation exposure can also increase the risk, and some leukemia subtypes are associated with inherited genetic predisposition.

However, most children diagnosed with leukemia do not have an identifiable risk factor.

Importantly, childhood leukemia is not caused by something a parent did or did not do. In most cases, there is no known way a family could have prevented the disease.

What are the signs and symptoms?

Many symptoms of leukemia result from the bone marrow’s inability to produce enough healthy blood cells.

A child with leukemia may experience:

• Fatigue, weakness or unusual paleness caused by anemia
• Frequent infections or persistent fever
• Easy bruising or bleeding
• Bone or joint pain
• Swollen lymph nodes
• An enlarged liver or spleen
• Headaches or other symptoms

These symptoms can also occur with many childhood illnesses that are not cancer. Having one or more of these symptoms does not mean a child has leukemia. When symptoms are persistent or concerning, a healthcare provider can determine whether further evaluation is needed.

How is pediatric leukemia diagnosed?

Diagnosis typically begins with a complete blood count (CBC), a routine blood test that measures different types of blood cells. A blood smear may also provide additional information about the appearance of the cells.

If leukemia is suspected, doctors generally perform a bone marrow aspiration and biopsy. This involves collecting a small sample of bone marrow so that the cells can be examined in detail.

Additional testing helps doctors determine exactly what type of leukemia is present and how it may respond to treatment. This can include:

• Flow cytometry, which identifies characteristics of abnormal cells
• Cytogenetic testing, which looks for changes in chromosomes
• Molecular testing, which identifies specific genetic changes
• Lumbar puncture, sometimes called a spinal tap, to examine spinal fluid for leukemia cells

These tests are important because leukemia is not a single disease. Understanding the specific characteristics of a child’s leukemia helps doctors determine the most appropriate treatment approach.

How is childhood leukemia treated?

Treatment is tailored to the type and characteristics of the leukemia, the child’s age and other factors, including how the disease responds to treatment.

For many children, treatment involves multiple phases of therapy. For ALL, for example, these phases commonly include induction, consolidation and maintenance.

• Induction is designed to achieve remission by eliminating as much leukemia as possible.
• Consolidation uses additional treatment to eliminate remaining leukemia cells and reduce the risk of relapse.
• Maintenance provides longer-term treatment intended to keep the leukemia from returning.

Treatment can last two to three years for some children, although the length and intensity vary depending on the disease and treatment plan.

Beyond traditional chemotherapy

Chemotherapy remains an important part of treatment for many children with leukemia, but treatment options have expanded significantly.

Depending on the type and characteristics of the disease, treatment may also include:

• Targeted therapy, which is designed to act on specific genetic or molecular abnormalities in leukemia cells
• Immunotherapy, which helps the immune system recognize and attack leukemia cells
• Stem cell transplantation, which may be used for some children with high-risk or relapsed disease
• Intrathecal chemotherapy, in which medication is delivered directly into the spinal fluid to protect against or treat leukemia in the central nervous system

Supportive care is also a critical part of treatment. Children may need blood or platelet transfusions, medications to prevent or treat infections, and psychosocial support for themselves and their families.

What do remission, MRD and relapse mean?

Several terms are commonly used when doctors discuss how a child is responding to leukemia treatment.

• Remission means that leukemia cannot be detected using standard methods. Importantly, remission does not necessarily mean that every leukemia cell has been eliminated.
• Minimal residual disease (MRD) refers to very small amounts of leukemia that may remain after treatment and can only be detected using highly sensitive testing. MRD can provide important information about how well a child is responding to treatment and can help doctors determine the appropriate intensity of therapy.
• Relapse occurs when leukemia returns after a period of remission.

Understanding which children are most likely to relapse—and how to identify and treat leukemia that remains after therapy—is an important area of ongoing research.

How have outcomes changed?

The outlook for children with leukemia has changed dramatically over the past several decades.

In the 1960s, childhood ALL was almost uniformly fatal. Today, the five-year survival rate for childhood ALL exceeds 90%. For childhood AML, five-year survival is approximately 65–70%.

These improvements represent decades of research into the biology of leukemia, treatment approaches, supportive care and ways to identify which therapies are most effective for individual patients.

At the same time, survival statistics do not tell the entire story.

Outcomes can vary based on the type and subtype of leukemia, genetic characteristics, a child’s age, the disease’s response to treatment and whether the leukemia returns.

And even when treatment is successful, intensive cancer therapy can have lasting effects. Childhood cancer survivors may experience late effects involving the heart, endocrine system, learning and development, or other aspects of long-term health. Some may also face an increased risk of developing a second cancer.

That means the goal of leukemia research isn’t simply to help more children survive. It is also to develop treatments that are more precise, less toxic and better able to preserve children’s long-term health and quality of life.

Why leukemia research continues to matter

The progress made in childhood leukemia demonstrates what cancer research can accomplish. Treatments that were once unsuccessful can become highly effective as researchers learn more about how cancer develops and how individual diseases respond to therapy.

But important questions remain.

Researchers continue to study why leukemia develops, why some children respond differently to the same treatment, how to detect remaining disease more accurately, why leukemia returns in some patients, and how to develop therapies that target cancer cells while reducing damage to healthy tissue.

New approaches—including targeted therapies and immunotherapies—are expanding the ways doctors can treat leukemia. At the same time, researchers are working to understand how genetic and molecular differences can help guide treatment for individual children.

Every advance builds on what researchers have learned before.

Key terms to know

• Anemia: A condition in which there are too few red blood cells, which can cause fatigue and paleness.
• Bone marrow: The spongy tissue inside bones where blood cells are produced.
• Blasts: Immature blood cells. In leukemia, abnormal blasts can accumulate in the bone marrow.
• CBC (complete blood count): A blood test that measures the number and characteristics of different blood cells.
• Chemotherapy: Medicines used to destroy cancer cells or prevent them from growing and dividing.
• Central line or port: A device placed into a large vein that allows medications to be given and blood to be drawn without repeated needle sticks.
• Flow cytometry: A laboratory test used to identify characteristics of blood or bone marrow cells and help determine the type of leukemia.
• Intrathecal chemotherapy: Chemotherapy delivered directly into the spinal fluid.
• MRD (minimal residual disease): A very small amount of leukemia that remains after treatment and can only be detected with sensitive testing.
• Neutropenia: A low number of neutrophils, a type of white blood cell that helps fight infection.
• Platelets: Blood cells that help the body stop bleeding. A low platelet count is called thrombocytopenia.
• Relapse: The return of leukemia after a period of remission.
• Remission: A state in which leukemia cannot be detected using standard testing. Remission does not necessarily mean that all leukemia cells have been eliminated.
• Stem cell transplant: A treatment in which diseased or damaged blood-forming cells are replaced with healthy stem cells, sometimes from a donor.
• Thrombocytopenia: A low platelet count that can increase the risk of bruising or bleeding.

Figures are approximate and reflect general U.S. statistics. Leukemia types, treatment approaches and outcomes vary, and information about an individual child’s diagnosis and treatment should always come from their medical team.