Leukemia Facts

Leukemia is cancer of the blood. It begins in the bone marrow, where blood cells are produced. Bone marrow is found in the soft, spongy center of the long bones of the arms and legs. These bones make the three major types of blood cells. White blood cells fight infection. Red blood cells carry oxygen. Platelets make the blood clot and stop bleeding.

In leukemia, there are too many underdeveloped cells in the blood and bone marrow. These crowd out normal, healthy blood cells that the body needs.

Learn more about:

• Types
• Symptoms
• Diagnosis
• Risk Factors
• Definitions

Types of Leukemia

There are two major types of leukemia - acute leukemia and chronic leukemia. Almost all children who have leukemia have an acute form. Acute leukemia grows rapidly and worsens quickly if your child does not get treatment.  Chronic leukemia develops more slowly.

 

Acute Leukemia

There are two types of acute leukemia. They are named for the type of blood cell that is cancerous.

• Acute Lymphocytic Leukemia (ALL) 
  ALL is the most common type of cancer in children. It arises from white blood cells called lymphocytes. Healthy lymphocytes circulate in the lymph system and bloodstream to fight infection. In ALL, these cells do not mature the way they should, so they cannot fight infection well. As a result, children with ALL are more prone to infections.

• Acute Myeloid Leukemia (AML)
  Acute myelogenous leukemia can arise from many types of blood cells that are still developing. All the cells affected by AML start as myeloid stem cells. In a healthy body, some of myeloid stem cells will turn into red blood cells, some into platelets and some into myeloblasts. The myeloblasts go on to become white blood cells called granulocytes.

Chronic Leukemia

Chronic leukemia is much less common in children than acute leukemia.

• Chronic Myeloid Leukemia (CML)
  About two to three percent of children with leukemia have chronic myelogenous leukemia. It is like AML except that some blood cells develop and work fine, so the early part of the disease is often less severe. CML in children is treated with chemotherapy given by mouth and for some patients a bone-marrow (hematopoietic stem cell) transplant.

 

Other Types of Leukemia

Children can have other kinds of leukemia, too.

• Juvenile Myelomonocytic Leukemia (JMML)
  About one to two percent of children with leukemia have juvenile myelomonocytic leukemia. It mainly affects children younger than four years old. JMML is a very hard type of leukemia to treat. The current treatment includes chemotherapy and a bone-marrow transplant.

• Myelodysplastic Syndrome (MDS)
  Another disease related to leukemia is called myelodysplastic syndrome, or MDS. In MDS, the child's bone marrow does not make enough white blood cells, red blood cells, and platelets. MDS can range from mild to severe. The best treatment for a person with MDS depends on the type of MDS, age, and overall health. Treatment options include managing systems with medications, chemotherapy, bone-marrow transplant, or new drug therapies.

Symptoms

ALL and AML have similar signs and symptoms because in both types of leukemia the cancerous cells crowd out healthy blood cells. The same symptoms can also be caused by other noncancerous conditions. So it’s important to have a doctor investigate if your child has these symptoms:

• Fever, which may be a sign of infection
• Easy bruising or bleeding, even from small injuries
• Petechiae, which are pinpoint spots of blood under the skin caused by tiny broken blood vessels
• Bone or joint pain, from leukemic cells collecting there
• Painless lumps in the neck, underarm, stomach, groin and possibly around the eyes
• Pain and fullness under the ribs, from enlargement of the liver and spleen
• Weakness and fatigue
• Loss of appetite
• Shortness of breath or coughing, from swelling of the thymus (a gland in the neck that is related to the immune system)

Diagnosis

To find out whether your child has leukemia, your child’s doctor will first do a thorough physical exam and ask about your child’s health history. Next the doctor will probably perform a series of blood tests to tell whether any blood cells are unhealthy and, if so, which type. Common blood tests to check for leukemia include the following:

• Complete blood count, or CBC: to determine how many cells of each type are circulating in the bloodstream
• Peripheral blood smear: to look at the appearance of the blood cells
• Blood chemistry: to look for chemicals in the blood that can be abnormal in people who have cancer

For a clear diagnosis, doctors may need to perform a bone marrow aspirate and sometimes a bone marrow biopsy. A small area of skin over the pelvis (the bone that makes up part of the hip) will be cleaned and numbed. Then, a teaspoon of bone marrow will be withdrawn with a needle (aspirate). Your child will receive medicines to help with any pain or discomfort associated with this procedure.

 
More specific laboratory tests of the blood can give your child’s doctors more information about the type of cells affected. These include tests that identify proteins on the surface of the leukemic cells and tests that look at the arrangement of chromosomes in the leukemic cells.

Doctors may do further tests to detect whether the cancer has spread to parts of your child’s body beyond the blood. For instance, a lumbar puncture, or spinal tap, may be done to remove cerebrospinal fluid (CSF) from the spinal column using a needle. If there are leukemic cells in the CSF, doctors know the brain and spinal cord may be affected by the cancer. A chest X-ray can provide a view into the chest area. A biopsy of the testicles, ovaries or skin helps doctors determine whether the cancer has spread there.

Based on what they learn through their diagnostic tests, doctors may classify your child’s leukemia into a category. The categories are designed to help doctors select the most appropriate treatment for each child.

With ALL, the treatment is based on the child’s age, white blood count, the type of lymphoblasts (T cell or B cell), the chromosomes in the leukemia, and the response to therapy. In general there are three groups:

• Standard risk: This applies to children ages one through 10 whose white blood cell count at the time of diagnosis is less than 50,000 per cubic millimeter.
• High risk: This applies to children who are ten years or older, and to children whose white blood cell count at the time of diagnosis is 50,000 or more per cubic millimeter.
• Very high risk: This applies to infants, children with some abnormal chromosomes in the leukemia cells, and those who do not go into remission quickly.

With AML, there are no risk groups assigned at the time of diagnosis. Certain features of the leukemia can make the disease higher risk. These features include poor response to initial therapy and some chromosomal abnormalities of the leukemia.

 

Risk Factors

Doctors do not know what causes leukemia in children. There are several factors that may increase a child’s risk. These factors are similar but not identical for ALL and AML. Most children who have leukemia have none of these risk factors.

This list is based on information from the Childhood Acute Lymphoblastic Leukemia “PDQ” summary and the Childhood Acute Myeloid Leukemia “PDQ” summary on the National Cancer Institute web site.

Childhood Leukemia Risk Factors

Risk Factor	ALL	AML
Sibling who has had leukemia	X	X, especially if they are twins
White ethnicity	X
Hispanic ethnicity	X	X
Live in the United States	X
Exposed to X-rays before birth	X
Exposed to large doses of radiation	X	X
Previous treatment with chemotherapy	X	X
Immune deficiencies	X
Certain genetic disorders, including Down syndrome	X	X
Exposed to cigarette smoke or alcohol before birth		X
Exposed to chemicals such as benzene		X
Certain previous disorders of the blood cells	X	X