The Pediatric Leukemia and Lymphoma Program at the Cancer Center at The Children's Hospital of Philadelphia consists of a multidisciplinary team of experts in treating leukemia. In addition, many of our physicians are at the forefront of researching and developing new therapies to treat the disease.
Leukemia is a cancer of the bone marrow and blood and is the most common type of childhood cancer. The bone marrow is the soft, spongy center of the bones and produces the three types of blood cells: white blood cells that fight infection, red blood cells that carry oxygen, and platelets that help with blood clotting and bleeding.
When a child has leukemia, the bone marrow begins to make blood cells that don't mature properly. The immature cells continue to reproduce, crowding out the healthy ones. Normal, healthy cells reproduce only when they have sufficient space.
Additionally, the body regulates the production of cells by sending signals to start and stop reproducing and to die. When leukemia occurs, the leukemic cells can send fraudulent signals to the normal cells that tell them not to reproduce; at the same time, the leukemia cells don't respond to the signal to stop reproducing. It is not yet understood how this happens.
The majority of leukemias in children result from a chance mutation in a gene or genes that enable the leukemic cells to reproduce.
Some factors such as infections with certain viruses, chemicals or medications have been associated with the development of pediatric leukemia. Rare inherited diseases that affect the production of bone marrow cells also predispose some people to develop leukemia. However, little is known about the actual causes of the great majority of cases of childhood leukemia.
Leukemia can occur at any age, but is most commonly seen in children aged 2 to 6 years. It occurs slightly more often in males than females. Children of Caucasian origin are more likely to have leukemia than children of other races. Children with ataxia-telangectasia are at risk of developing leukemia and lymphomas. Children with Down syndrome are at a higher risk of developing leukemia as are children with certain rare genetic syndromes including Fanconi anemia, Bloom syndrome, Shwachman-Diamond syndrome and Kostmann syndrome. However, most leukemia occurs in otherwise healthy children with no recognizable abnormalities.
The major types of leukemia that occur in children are:
The most common signs and symptoms of leukemia in children are:
Anemia results when normal red blood cells are unable to be produced due to overcrowding of the bone marrow space by leukemic cells. The child may appear tired, pale, and may breathe faster to compensate for the decrease in oxygen-carrying capacity. The number of red blood cells on a blood count (expressed as "hemoglobin" or "hematocrit") will be below normal.
Bleeding and/or bruising
When the marrow cannot produce enough platelets, bleeding can occur, especially when the platelet numbers are less than 10-20,000/mm3. Low platelets can cause a child to bruise easily.
Fever and persistent or unusual infections
The child with leukemia often shows non-specific symptoms of infection such as fever and fatigue. Although the blood count of a child with leukemia may show a high number of white blood cells, these cells are immature and do not normally fight infection. As a result, the child may have difficulty recovering from an ordinary childhood infection or may develop unusual infections.
Bone and joint pain
Pain in bones and joints is another common symptom of leukemia; this pain is usually a result of the bone marrow being crowded with leukemic blasts.
Abdominal pain may also be a symptom of leukemia. Leukemia cells can collect in the kidneys, liver, spleen and intestines, causing enlargement of these organs. Pain in the abdomen may cause a child to have loss of appetite and weight loss.
Swollen lymph nodes
Lymph nodes filter the blood. Leukemia cells often collect in the nodes, causing swelling. Swelling occurs in lymph nodes under the arms, in the groin, chest and in the neck. Sometimes it is difficult to distinguish the lymph nodes of leukemia from those that are a normal part of the body's response to infection or allergy.
Difficulty breathing (dyspnea)
In leukemia, especially T-cell ALL leukemia, cells can clump together in the thymus a gland under the breastbone and around the throat. This mass of cells can cause difficulty breathing. Any wheezing, coughing and/or labored or painful breathing requires immediate medical attention.
The diagnosis of leukemia in children is based on a complete medical history and physical examination and on the following diagnostic tests:
Blood tests may be done to evaluate the liver and kidneys and how the blood is clotting, and to conduct genetic studies. Blood may be removed from a vein with a needle or a central venous line. When a central venous line is used, a plastic tube or catheter is inserted into a large vein in the chest, neck or arm. This is also a common way to give chemotherapy. The use of a central line prevents a lot of needle sticks.
Bone marrow aspirates and biopsies involve inserting a needle into a bone in the pelvis or spine and removing about 2 teaspoons of marrow for examination. Bone marrow studies require pain medicine and usually sedation or general anesthesia.
Spinal taps involve inserting a needle into the lower back, between the bones of the spinal column or backbone, to remove the fluid that surrounds the brain and spinal cord. The same needle can be used to insert medicines to prevent or treat leukemia in the brain or spinal cord (intrathecal chemotherapy).
Chest x-rays are taken to see if there is a mass of cells in the thymus that may affect breathing.
Treatment usually begins by addressing the signs and symptoms your child has such as anemia, bleeding and/or infection. In addition, treatment for leukemia may include some or all of the following:
Chemotherapy refers to medicines that help fight cancer. They are given by mouth, in the vein, in the muscle or under the skin. Intrathecal chemotherapy is chemotherapy that is injected into the spinal fluid to prevent or treat leukemia in the brain and spinal cord.
Intrathecal medications/chemotherapy involves inserting medications through a needle into the fluid-filled space surrounding the spinal cord.
Radiation therapy uses high-energy waves such as x-rays to kill or shrink cancer cells. It is sometimes used to treat leukemia in the central nervous system or other places such as the eye or the testes.
Blood and marrow transplantation consists of three steps: 1) collection of healthy stem cells from a donor without cancer or from the patient himself or herself; 2) administration of high doses of chemotherapy and possibly radiation therapy to kill any remaining leukemia cells; and 3) infusion of the healthy stem cells through an intravenous line to produce normal blood-forming cells. Bone marrow or stem cell transplantation is commonly used to treat ALL that has not responded to chemotherapy.
Biological therapy consists of high doses of hormones or other proteins that are normally made by the human body; pharmaceutical companies make these substances. They are used to prevent or treat damage to other systems of the body caused by leukemia treatment.
Blood transfusions are sometimes used for patients who have anemia who cannot make their own red blood cells. Platelets are commonly transfused when platelet counts are low. White blood cells are occasionally transfused to treat severe infections that do not respond to antibiotics. Plasma, the fluid part of blood in which the blood cells are suspended, is transfused in patients who are not able to make the proteins that clot the blood.
Antibiotics. Antibiotics are used to prevent or treat infections.
Treatment of pediatric leukemia takes months or years and takes place in three or more stages, as described below.
Induction. Induction refers to the first month or so of treatment in which a combination of chemotherapeutic drugs is given to reduce the numbers of leukemia cells from billions to millions. The goal in this stage of treatment is to reduce the number of leukemia cells in the marrow to less than 1 in 20 (5%) and to make room for the return of the normal red blood cells, white blood cells and platelets. When this happens, the leukemia is said to be in "remission." This phase may last approximately one month and can be repeated if the goal is not achieved.
Consolidation. In ALL, consolidation involves one or two months of drug treatment. During this phase, leukemia cells are still present in the body although they may not be detectable in a blood test or bone marrow examination.
Intensification. In ALL, intensification involves repeating chemotherapy combinations similar to those used in induction and consolidation several months later. It may involve bone marrow or stem cell transplantation or higher-dose chemotherapy. AML treatment often stops at this point.
Maintenance. This treatment stage further reduces the number of leukemia cells through the use of repeated courses of less intense chemotherapy every 28 days for an additional 18 months in girls and 30 months in boys. Regular outpatient visits are required to determine response to treatment, detect any recurrent disease and manage any side effects of the treatment.
Some children treated for leukemia may develop complications years later. Our Cancer Survivorship Program provides information about the potential long-term effects of the specific treatment your child received, including ways of monitoring and treating these effects.
Reviewed by: Beverly J. Lange, MD, The Children's Hospital of Philadelphia
Date: May 2005
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