Leukemia is the most common childhood cancer, making up about 1/3 of all pediatric cancers. In the United States, about 3,500 children get a leukemia diagnosis each year.
The disease starts in the bone marrow, where new blood cells are made. In a healthy person, blood stem cells in the 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 multiply quickly, crowding out healthy cells in the marrow and in the bloodstream.
There two main types of leukemia, depending on the type of blood stem cell that causes the cancer. Lymphoid stem cells should make different types of healthy white blood cells, which are used to fight off infection. In lymphocytic (or lymphoblastic) leukemia, too many of these cells are made. These cancerous cells are poor at fighting infection.
Myeloid stem cells produce different types of blood cells, including red and white blood cells. Myeloid (or myelogenous) leukemia occurs when an immature type of white blood cell, called a myeloblast, becomes cancerous. Just like in lymphotic leukemia, these cells multiply rapidly and crowd out healthy cells.
Both types of leukemia are classified as either acute or chronic. Acute is fast moving, while chronic develops at a much slower rate. Children almost never have chronic leukemia. About 75% of childhood cases are acute lymphoblastic leukemia (ALL), with most of the rest being acute myeloid leukemia (AML).
Childhood leukemia risk factors
There’s no know 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:
- Bloom syndrome
- Diamond-Blackfan anemia
- Down syndrome
- Fanconi anemia
- Klinefelter syndrome
- Li-Fraumeni syndrome
- Schwachman-Diamond syndrome
- Trisomy 8
- Severe congenital neutropenia (also called Kostmann syndrome)
Other possible risk factors include having a sibling with the disease or exposure to high levels or radiation or certain chemicals, including benzene, which is used in oil refineries, chemical plants and other industries.
In addition, people who are treated for another cancer with certain chemotherapy drugs are at a higher risk of developing the leukemia. Every cancer survivorship program should screen for this type of leukemia.
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 that can be passed 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.