The disease starts in the bone marrow, where new blood cells are made. In a healthy person, blood stem cells in the bone marrow develop into the different types of healthy blood cells. When a child develops leukemia, some of these cells become abnormal and cancerous. They don’t do their job well and they crowd out healthy cells in the bone marrow and in the bloodstream.

Most leukemia cases fall into one of two categories, chronic and acute. Chronic leukemia involves mature or partially mature cells and is slow growing. It is also rare in children. Acute leukemia impacts immature cells. It is more aggressive and makes up the vast majority of childhood leukemia cases.

Childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common type of childhood leukemia, making up about 75% of all childhood leukemia cases. It’s also the most treatable type of childhood leukemia, with a five-year survival rate of around 90%.

ALL impacts lymphoid stem cells. In healthy bone marrow lymphoid stem cells make lymphoblasts. These lymphoblasts then turn into different types of healthy white blood cells, which are used to fight off infection.

In ALL, lymphoid stem cells make large numbers of diseased lymphoblasts and diseased white blood cells. These cancerous cells are poor at fighting infection and crowd out healthy cells.

Childhood ALL can be classified into two main subtypes, based on the kind of cell that’s the source of the cancer. B-cell ALL accounts for 80-85% of childhood ALL cases. The remaining 15-20% are T-cell ALL cases. This subtype is more common in boys than girls.

Childhood acute myeloid leukemia

Acute myeloid leukemia (AML) is the second most common type of childhood leukemia. The disease’s five-year survival rate for pediatric patients is about 65%, though that figure differs from subtype to subtype. Many of these subtypes are based on chromosome changes in the cancerous cells.

AML affects myeloid stem cells. These stem cells make three blood components:

• Red blood cells, which deliver oxygen throughout the body
• White blood cells, which help fight infection
• Platelets, which help blood form clots.

AML occurs when an immature type of white blood cell, called a myeloblast, becomes cancerous. In some cases, the myeloid stem cells produce too many diseased red blood cells and platelets. These cells don’t do their job well and multiply so rapidly that they crowd out healthy cells.

Childhood chronic myeloid leukemia

Chronic myeloid leukemia (CML) is rare in children. In the United States, fewer than 200 people under age 20 are diagnosed with CML each year. Most cases are in teenage patients.

Like AML, CML starts with myeloid stem cells in the bone marrow. These cells make several blood components, including certain types of white blood cells.

In CML, one kind of white blood cell, called a granulocyte or a blast, becomes diseased. These cells are not good at fighting infection. They are also long-lived and eventually start crowding out healthy white blood cells. This makes CML a slow-growing disease. Patients can live for years with few symptoms.

The treatment of pediatric CML is similar to the treatment for adults with the disease and include targeted therapies and stem cell transplantations.

Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare type of leukemia, mostly found in children age four and younger. In JMML, the diseased cells are monocytes, a type of white blood cell. JMML is faster growing than chronic leukemia and slower growing than acute. It shares many symptoms with other types of leukemia, including a pale complexion, fever and infections. Since JMML cells gather in certain organs, symptoms can also include an enlarged spleen and difficulty breathing caused by cancer cells accumulating in the lungs. A stem cell transplant is the recommended treatment for JMML, though about half of patients who undergo a successful transplant relapse.

Childhood leukemia risk factors

There’s no known way to prevent leukemia, but there are several risk factors that may increase a person’s chance of developing the disease. These include having one of several genetic disorders, including: 

• Ataxia-telangiectasia
• Bloom syndrome
• Diamond-Blackfan anemia
• Down syndrome
• Fanconi anemia
• Klinefelter syndrome
• Li-Fraumeni syndrome
• Neurofibromatosis
• Schwachman-Diamond syndrome
• Trisomy 8
• Severe congenital neutropenia (also called Kostmann syndrome)

Other possible risk factors include:

• having a sibling with the disease;
• exposure to x-rays, alcohol or cigarette smoke before birth
• exposure to high levels of radiation or certain chemicals, including benzene, which is used in oil refineries, chemical plants and other industries.

In addition, children who are treated for another cancer with certain chemotherapy drugs are at a higher risk of developing leukemia. Every cancer survivorship program should screen for leukemia because of this.

Most cases of leukemia are not inherited. The rare hereditary forms of the disease are caused by a mutation in the patient’s DNA that can be passed down from one generation to another. Sometimes the patient gets this mutation from a parent. Sometimes it is an entirely new mutation that the patient did not inherit, but can pass down to his or her children.

MD Anderson’s Childhood Cancer Survivorship Clinic can screen for chemotherapy-related leukemia for anyone who was diagnosed with cancer before age 21, as well as provide care for all pediatric cancer survivors. 

In rare cases, childhood leukemia can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family on our genetic testing page.

Learn more about childhood leukemia:

• Childhood leukemia symptoms
• Childhood leukemia diagnosis
• Childhood leukemia treatment

Why choose MD Anderson for childhood leukemia treatment?

Selecting a hospital is the first big choice a family makes after a cancer diagnosis. MD Anderson’s Children’s Cancer Hospital offers childhood leukemia patients the most advanced treatments from an expert team, along with support services designed to help the entire family through their cancer journey.

This journey starts with a diagnosis of each patient’s leukemia that is far more detailed and accurate than most hospitals. Through the skills of our leading pathologists, MD Anderson is able to quickly pinpoint alterations in the cancer cells. This information can be used to develop treatment plans tailored to each individual patient.

These treatment plans are created by our multidisciplinary team of physicians working together to benefit each patient. Among these physicians are leading medical oncologists who focus exclusively on treating childhood leukemia and related conditions and specialists from one of the largest stem cell transplantation services in the country. Their expertise includes caring for the newly diagnosed, as well as patients whose leukemia has relapsed or not responded to treatment.

While here, pediatric leukemia patients have access to clinical trials for children, teens and even adults. We’re also home to advanced treatments such as CAR T-cell therapy, which is only available at a few hospitals in the United States.

In addition, the Children’s Cancer Hospital offers supportive care services designed to improve your child’s quality of life, such as counseling and symptom management services. Patients also have access to programs like our arts in medicine activities, summer camps and support groups. We even have an accredited, in-hospital school that helps patients meet their academic goals while still in treatment.