Onconurse.com Fact Sheet Childhood

The word leukemia literally means “white .” fungi. WBCs are produced and stored in the bone mar- Leukemia is the term used to describe of the row and are released when needed by the body. If an blood-forming tissues known as . This is present, the body produces extra WBCs. spongy material fills the long bones in the body and There are two main types of WBCs: produces blood cells. In leukemia, the bone marrow • . There are two types that interact to factory creates an overabundance of diseased white prevent infection, fight viruses and fungi, and pro- cells that cannot perform their normal function of fight- vide immunity to disease: ing infection. As the bone marrow becomes packed with diseased white cells, production of red cells (which ° T cells attack infected cells, foreign tissue, carry oxygen and nutrients to body tissues) and and cancer cells. (which help form clots to stop bleeding) slows B cells produce antibodies which destroy and stops. This results in a low red count ° foreign substances. () and a low count (thrombocytopenia). • . There are four types that are the first Leukemia is a disease of the blood defense against infection: Blood is a vital liquid which supplies oxygen, food, hor- ° are cells that contain enzymes that mones, and other necessary chemicals to all of the kill foreign bacteria. body’s cells. It also removes toxins and other waste products from the cells. Blood helps the lymph system ° are the most numerous WBCs to fight infection and carries the cells necessary for and are important in responding to foreign repairing injuries. Blood also contains important clotting bacteria. factors. ° Eosinophils respond to allergic reactions as Whole blood is made up of plasma, which is a clear well as foreign bacteria and parasites. fluid, and many other components, each with a specif- ° Basophils are the rarest of the white cells and ic task. The three main elements involved in leukemia play a special role in allergic reactions. are red blood cells, platelets, and white blood cells. The different types of leukemia are of a specif- Red blood cells (erythrocytes or RBCs) contain hemo- ic type. For instance, acute lym- globin, a protein that picks up oxygen in the and phoblastic leukemia affects only lymphocytes. transports it throughout the body. RBCs give blood its red color. When leukemia cells in the bone marrow What is a blast? slow down the production of red cells, the child devel- “Blast” is a short name for an immature white blood cell ops anemia. Anemia can cause tiredness, weakness, irri- such as lymphoblast, , or monoblast. Nor- tability, pale skin, and headache. mally, less than 5 percent of the cells contained in Platelets (thrombocytes) are tiny, disc-shaped cells that healthy bone marrow at any one time are blasts. Normal help form clots to stop bleeding. Leukemia can dramat- blasts develop into mature, functioning white blood ically slow down the production of platelets, causing cells, and are not usually found in the bloodstream. children to bleed excessively from cuts or in some cases Leukemic blasts remain immature, multiply continuous- from their nose or gums. Children with leukemia can ly, provide no defense against infection, and may be develop large bruises or small red dots (called petechi- present in large numbers in the bloodstream. ae) on their skin. White blood cells (leukocytes or WBCs) destroy foreign How does leukemia begin? substances in the body such as viruses, bacteria, and When a population of abnormal blasts appears in the bone marrow, they multiply rapidly and lose their abil-

1 Onconurse.com Fact Sheet Childhood Leukemia ity to grow up into normal white cells. They begin to merely an association. In cases where one identical twin crowd out the normal cells that usually develop there. has leukemia, the other twin has a 25 percent chance of After accumulating in the bone marrow, leukemic cells developing the disease within one year, but this risk spill over into the blood. Leukemic cells may also cross decreases with an older age at diagnosis and with time. the blood-brain barrier and invade the central nervous It is not known whether this is caused by an inherited system (brain and spinal cord). trait or a simultaneous exposure to the same carcino- gen. Leukemia is not contagious; it cannot be passed When the leukemic blasts begin to fill the marrow, pro- from one person to another. duction of healthy red cells, platelets, and white cells cannot be normally maintained. As the number of nor- Environmental factors mal cells decreases, symptoms appear. Low red cell Exposure to and certain toxic chemi- counts cause fatigue and pale skin. Low platelet counts cals may predispose individuals to leukemia and other may result in bruising and bleeding problems. If mature problems involving the bone marrow. Many Japanese neutrophils and lymphoblasts are crowded out by the who were exposed to fallout from the atomic bomb blasts, the child will have little or no defense against during World War II and some of the people living near . the Chernobyl accident in the Ukraine have developed leukemia. Chronic exposure to benzene has been asso- Who gets leukemia? ciated with leukemia in adults. However, most children Acute leukemia is the most common . are not exposed to large amounts of radiation or indus- Although generally thought of as strictly a childhood trial chemicals. The data so far indicates that there is no disease, many more adults than children develop increased risk of leukemia from exposure to electro- leukemia. Each year in the United States, approximate- magnetic fields. Although scientists are examining asso- ly 25,000 adults and 2,500 children are diagnosed with ciations with many environmental factors, there are no acute leukemia. clear environmental causes of childhood leukemia. Childhood leukemia is most commonly diagnosed at Rates of childhood cancer have increased every year for ages two to seven, with the highest incidence at approx- the last three decades. In response to this and other imately four years of age. In the United States, leukemia threats to children’s health, in 1997 the US formed the is more common in whites than in blacks, and boys Federal Task Force on Protecting Children from Environ- have a slightly higher incidence than girls. Children with mental Health Risks and Safety Risks. Information on genetic diseases such as , Bloom’s syn- this task force can be found on the Internet at drome, or Fanconi’s anemia have a higher risk of devel- http://www.epa.gov/children/six.htm. oping leukemia than the general population. However, most children with these syndromes do not develop The US Environmental Protection Agency (EPA) has a leukemia. Children’s Health Resources branch that maintains pub- lications on children’s health topics, information on hot Although the exact cause of childhood leukemia is a lines, and links to Internet resources at (888) 372-8255 mystery, certain factors are known to increase the risk and on the Internet at http://www.epa.gov/children. of developing the disease. For information about the US government’s electromag- Genetic factors netic field (EMF) research efforts, including public infor- It is known that persons with extra chromosomes mation materials developed by the EMF RAPID pro- (genetic material contained in cells) or certain chromo- gram, refer to the EMF RAPID home page on the somal abnormalities have a greater chance of develop- Internet: http://www.niehs.nih.gov/emfrapid/home.htm. ing leukemia. It is uncertain whether this is a cause or

2 Onconurse.com Fact Sheet Childhood Leukemia

Viral factors Children with AML are sometimes diagnosed after Viruses that cause leukemia in cows, cats, chickens, gib- developing a chloroma—a tumor arising from myeloid bons, and mice have been found. A T-cell virus has tissue and containing a pale green pigment. These are been identified which causes a rare type of leukemia- most often found under the skin of the skull. in adults; however, no virus has been found To confirm a diagnosis of leukemia, bone marrow is which causes the types of leukemia commonly found in sampled and tested. The bone marrow is examined children. microscopically by a pediatric oncologist and/or a Currently, it is thought that a complex interaction pathologist, a physician who specializes in body tissue among genetic, environmental, immunologic, and pos- analysis. More than 25 percent blasts in the marrow sibly viral factors predisposes individuals to leukemia. confirms the diagnosis of leukemia. A portion of the The most important point for parents to remember is bone marrow (and chloroma if done) is sent to that at present there is no way to predict or prevent a specialized laboratory that analyzes many other fea- leukemia. Nothing that parents did or did not do caused tures of the leukemic cells to help determine which type or could have prevented the leukemia. of leukemia is present.

How is leukemia diagnosed? How is leukemia best treated? A tentative diagnosis is made after a physical examina- At diagnosis, parents are often confused about how to tion of the child and microscopic analysis of a blood find the best doctors and treatment plan for their child. sample. Physical findings may include pale skin; bruis- The best care available in the US and Canada is ing or unusual bleeding; enlarged liver, , or obtained from institutions that are part of the Children’s lymph nodes; ear or other infections (frequently resist- Cancer Group or the Pediatric Oncology Group. These ant to treatment); weakness; and fever. Parents or chil- study groups, composed of pediatric oncologists and dren may describe irritability, night sweats, fatigue, surgeons, urologists, radiation oncologists, researchers, bone pain, and loss of appetite. Blood tests may show and nurses, establish the standard of care for patients in decreased red cells, decreased platelets, and either the US and Canada, conduct new studies to discover abnormally low or high white blood cell counts. There better therapies or fine tune the old ones, and establish may be blast cells circulating in the blood. follow-up for survivors. They are in the process of merging into one entity called the Children’s Oncology The T-cell type of ALL sometimes involves the Group (COG). If the treatment center you are referred gland in the neck. Enlargement of the thymus can pres- to is a member of one of these groups, you can rest sure the nearby trachea (windpipe), causing coughing assured that your child will have access to the best or shortness of breath. The superior vena cava (SVC), a thinking on the treatment of pediatric cancers. large vein that carries blood from the head and arms back to the heart, passes next to the thymus. An enlarged thymus gland may compress the SVC and Types of leukemia cause swelling of the head and arms. The two broad classifications of leukemia are acute (rapid progression) and chronic (slow progression). The Some children with leukemia have the disease in their acute are characterized by abnormal numbers central nervous system (brain and spinal cord) at diag- of immature white cells (blasts). In chronic leukemia, nosis. Less than 10 percent of children or teens with mature white cells predominate. Chronic leukemia leukemia have symptoms of CNS disease, including accounts for less than 5 percent of all childhood headache, poor work or school performance, weakness, leukemia. seizures, vomiting, blurred vision, and difficulty in maintaining balance. Acute leukemia is the most common type of cancer found in children. The two most common types of acute

3 Onconurse.com Fact Sheet Childhood Leukemia leukemia are acute lymphoblastic leukemia (ALL) and teens but can strike children at any age. AML accounts (AML). AML is also known as for approximately 15 percent of all cases of childhood acute non-lymphoblastic leukemia (ANLL). leukemia. There are eight different classifications or types of AML (M0 to M7) based on appearance of the Acute lymphoblastic leukemia (ALL) diseased cells under the microscope. Seventy-five percent of all children with leukemia have ALL. It is caused by a rapid proliferation of immature Chronic myelogenous leukemia (CML) lymphocytes, which would normally have developed CML is rare in children, accounting for less than 5 per- into mature T cells or B cells. There are several sub- cent of all childhood leukemias. This disease is most groups of ALL based on whether the cancer cells devel- common in adults, but occasionally is diagnosed in oped from B cells or T cells, or display characteristics of older boys and girls. It is characterized by a very large both. The first sample of bone marrow taken from the spleen, high white count of mostly neutrophils and child is analyzed to identify cellular characteristics to other types of granulocytes, and high platelet count. help plan the best therapy as well predict response to Other symptoms of CML are fatigue, weakness, head- treatment. Each different subgroup has a different aches, irritability, fevers, night sweats, and weight loss. response to treatment; some require less , Some patients have no symptoms and the cancer is while others require aggressive treatment to achieve a diagnosed after a routine blood test done for other rea- cure. sons. There is no severe anemia or tendency to bleed. One child’s illness didn’t look so bleak to another In over 90 percent of patients with CML, analysis of the child’s parent: cells of the bone marrow shows a genetic abnormality called the . This chromosome I was walking around the hospital looking shell- contains a “translocation” or swap of genetic material shocked the day after my daughter had been involving chromosomes 9 and 22, abbreviated as t(9;22). admitted to Children’s Hospital with leukemia. One of the other mothers came up, introduced Symptoms did not initially suggest that this child had herself, and asked what we were in for. I told CML: her leukemia. She told me that her son had just Leah, eleven years old, enjoyed participating in relapsed again from a brain tumor. She looked basketball, soccer, and gymnastics. She devel- wistful and said how much she wished that her oped severe hip joint pain, and we brought her son had ALL. She said, “You might think that’s back to the doctor three times in an unsuccess- strange, but I see those kids come, get better, ful attempt to find out what was wrong. The last and go home. We are still here.” time, my husband had to carry her in because she couldn’t walk. They did blood work, and Acute myeloid leukemia (AML) her white count was 176,000 and her platelets AML (also called acute myelogenous leukemia, acute were one million. A bone marrow test con- nonlymphocytic leukemia, or ANLL) is cancer of the firmed that she had CML. bone marrow. The cancer cells are those that would otherwise develop into myeloid cells like granulocytes. Chronic myelomonocytic leukemia (CMML) Because treatments for AML and ALL are very different, Chronic myelomonocytic leukemia (also called juvenile it is crucial that sophisticated laboratory studies are per- CML or JCML) usually strikes children under five years formed on the bone marrow samples to determine of age. The symptoms are similar to those of the acute whether the child has AML or ALL. Eight thousand cases leukemias: pale skin, bruising, fatigue, headaches, of AML are diagnosed in the US each year, most often sweating, and recurrent infection. Also usually present in adults over forty. It is also seen in infants or older

4 Onconurse.com Fact Sheet Childhood Leukemia are enlarged lymph nodes, enlarged spleen and liver, there is no treatment besides BMT. It is also vast- and low platelet count. Unlike CML, CMML does not ly different from the adult CML. My daughter have a chronic phase. Once diagnosed, progressive had a mismatched (5/6) related (my husband’s deterioration usually occurs. sister as donor) BMT four months after she was diagnosed. Today, she is six years post-trans- Because chemotherapy is not generally a successful plant, is in the second grade, and is the absolute treatment for juvenile CML, bone marrow or stem cell joy of my life. transplantation is the best hope for cure. However, chemotherapy is sometimes used to get the disease This fact sheet was adapted from Childhood Leukemia: under control while preparing for transplant. A Guide for Families, Friends, and Caregivers, 2nd This child’s bone marrow transplant was successful: Edition, by Nancy Keene, © 1999 by Patient-Centered Guides. For more information, call (800) 998-9938 or My daughter was diagnosed with JCML is 1993 see www.patientcenters.com. at the age of 27 months. Although it is a chron- ic leukemia, it is particularly fast moving and

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