Leukemias are cancers that begin in tissues that produce blood cells. Leukemia, the most common form of childhood cancer, accounts for about 30 percent of all cancers that affect children and young adults.
Healthy bone marrow contains young cells that normally mature into blood cells, including platelets, red blood cells, and white blood cells. White blood cells normally help the body fight infection. However, in leukemia, changes occur in young white blood cells that prevent them from maturing properly. These abnormal white blood cells grow and multiply uncontrollably, flooding the body's organs and interfering with organ function. They also prevent normal blood cells from forming.
Types of Pediatric Leukemias
Leukemias are named after the specific type of white blood cell that is affected, such as lymphoid cells or myeloid cells.
There are two main types of leukemia in children and young adults. Acute lymphoblastic leukemia (ALL) is the most common type, accounting for about 85 percent of cases. Acute myelogenous leukemia (AML) is responsible for nearly 15 percent of all childhood leukemias. Another type of leukemia, rarely seen in children and more common in young adults, is chronic myelogenous leukemia (CML).
Each year in the United States, about 3,000 children and young adults are diagnosed with ALL, and about 300 are diagnosed with AML. Leukemias are slightly more common in males and in Caucasians. Leukemia can develop at any age, but the most likely age at diagnosis is between two and ten years of age.
More than 90 percent of children and young adults with leukemia complain of feeling tired or not feeling well. Other frequent symptoms include:
- Bone pain, which could be indicated by a young child limping or refusing to walk
- Signs of bleeding, including easy bruising or small spots of blood, called petechiae, under the skin
- Fevers that last for various amounts of time, with no apparent cause
- Recurrent infections
About 70 percent of children and young adults with leukemia who are examined by a physician have an enlarged liver, spleen, or lymph nodes.