Leukemia, the most common form of childhood cancer, is cancer of the blood that develops in the bone marrow. It affects nearly 3,000 children annually in the United States, accounting for about 30 percent of cancer cases among children. Although leukemia can occur at any age, it is most commonly diagnosed in children between 2 and 6 years old. The disease occurs more frequently in males than in females, and is more common among Caucasians than those of other races.
The two primary types of childhood leukemia are acute lymphocytic leukemia (ALL) and acute myelogenous leukemia (AML). These two acute forms of leukemia can develop over a short period of days to weeks. A third chronic form, called chronic myelogenous leukemia (CML), is rare among children.
Types of Leukemia
- Acute lymphocytic leukemia (ALL) — Also called lymphoblastic or lymphoid leukemia, ALL accounts for about 75 to 80 percent of childhood leukemia cases. In this form of the disease, the lymphocyte cells, which normally fight infection, are affected. The bone marrow makes too many lymphocyte cells that do not mature correctly. The lymphocyte cells overproduce, crowding out other blood cells. Immature blood cells don't work properly to fight infection. Chromosome abnormalities, or extra chromosomes and structural changes in the chromosome material, are present in the majority of ALL patients.
- Acute Myelogenous Leukemia (AML) — Also called granulocytic, myelocytic, myeloblastic or myeloid leukemia, AML accounts for about 20 percent of childhood leukemias. In patients with AML, too many granulocytes — a type of white blood cell that normally fights infection — are produced in the marrow and they don't mature correctly. The immature blood cells don't work properly to fight infection. The excessive number of these abnormal cells crowd out other healthy blood cells. Children with certain genetic syndromes, including Fanconi anemia, Bloom syndrome, Kostmann syndrome and Down syndrome, have a higher risk of developing AML.
- Chronic Myelogenous Leukemia (CML) — CML is the more slowly developing form of myelogenous leukemia and is rare among children. It may develop over a period of months or years. Children with CML have a chromosome rearrangement: Part of the ninth chromosome breaks off and attaches itself to chromosome number 22, creating an exchange of genetic material. This rearrangement changes the position and function of certain genes, causing uncontrolled cell growth. Other chromosome abnormalities also can occur.
Like all blood cells, leukemia cells travel throughout the body. Depending on the number of abnormal cells and where these cells collect, patients with leukemia may have a number of symptoms, including:
- Anemia — Children with leukemia often have fewer than normal healthy red blood cells and platelets. They lack enough red blood cells to carry oxygen through the body, which causes a condition called anemia. Children with anemia may look pale, feel weak and tired and bleed and bruise easily.
A number of diagnostic procedures may be performed, including:
- Blood tests — Blood tests are done frequently to monitor the possible side effects of chemotherapy and radiation therapy. Because the results can influence treatment decisions, these tests often are done before treatment.
- Cultures — If your child has a fever or other signs of infection, one or more samples of blood, urine or stool, throat secretion or pus may be taken to check for infection. To confirm an infection, any organisms contained in these samples are allowed to grow in a culture for several days. To get a head start at fighting the infection, however, antibiotics may be prescribed before your child's doctor has the final results of the culture.
Your child may undergo the following four types of treatment:
Chemotherapy involves drugs to kill cancer cells. These drugs may be taken orally or may be injected into by a needle into a vein or muscle. This type of therapy is called a systemic treatment because the drug enters the bloodstream, travels through the body and can kill cancer cells throughout the body. For acute lymphocytic leukemia (ALL), chemotherapy drugs may be injected through the spine into the fluid that surrounds the brain and spinal cord. This is known as intrathecal chemotherapy.
Radiation therapy uses X-rays or other high-energy rays to kill cancer cells and shrink tumors. Radiation for acute lymphocytic leukemia (ALL) usually comes from a machine outside the body, called external beam radiation therapy.
UCSF Research & Clinical Trials
Reviewed by health care specialists at UCSF Benioff Children's Hospital.
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