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                               Childhood Leukemia

What is Leukemia?

The term leukemia refers to cancers of the white blood cells. These cells are produced in the bone marrow to help or bodies fight infection.

When a child has leukemia, large numbers of abnormal white blood cells are produced in the bone marrow.

These abnormal white cells crowd the bone marrow and spill out into the bloodstream, but they cannot perform their proper role of protecting the body against disease.

As leukemia progresses, the cancer interferes with the body’s production of other types of blood cells, including red blood cells and platelets. This results in anemia (low numbers of red cells), bleeding problems, and increased risk of infection.

In general, leukemias are classified into acute (rapidly developing) and chronic (slowly developing) forms.
In children, the large majority of leukemias are acute and chronic leukemia is rare.

What are the types of acute leukemia in children?

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. 

Acute Lymphocytic Leukemia (ALL)

• ALL accounts for about 75 - 80% of childhood leukemia. In this form of the disease, the lymphocyte cells, which normally fight infection, are affected.
  

Incidence

• ALL is the most common malignancy diagnosed in children, representing nearly one third of all pediatric cancers.
• In the United States, about 2,500 - 3,000 children each year are found to have acute lymphoblastic leukemia.
• Peak incidence occurs from 3 to 5 years of age.

Causes

• Many environmental factors (eg, exposure to ionizing radiation and electromagnetic fields, parental use of alcohol and tobacco) have been investigated as potential risk factors, but none has been definitively shown to cause lymphoblastic leukemia.
  
  

Influencing Factors

• ALL affects slightly more boys than girls.
• It occurs more frequently among whites than blacks.
• Although siblings of leukemic children have a slightly higher risk of developing the disease, the incidence is relatively low (no more than one in 500).

Acute Myelogenous Leukemia (AML)

• AML accounts for about 20 percent of childhood leukemias. Acute myelogenous leukemia is a cancer of the blood in which too many granulocytes, a type of white blood cell that normally fights infection, are produced in the marrow and they don’t mature correctly. 
  
• Children with certain genetic syndromes, including Fanconi anemia, Bloom syndrome and Down syndrome, have a higher risk of developing AML.

What are the signs and symptoms of childhood leukemia?

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.

Here are some general leukemia symptoms:

Anemia — Children with leukemia often have fewer than normal healthy red blood cells.
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.

Easy Bruising and/or Bleeding  — Easy bruising or bleeding may occur if the child’s platelet counts are very low. Petechiae (flat, pinpoint spots under the skin caused by bleeding) may be seen.

Recurrent Infections — Although children with leukemia may have a high number of white blood cells, these white blood cells are immature and don’t fight infection. Children may experience repetitive viral or bacterial infections. They often have symptoms of infection such as fever, runny nose and cough.

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 overcrowded and "full."

Abdominal Pain — Leukemia cells can collect in the kidney, liver and spleen, causing enlargement of these organs. Pain in the abdomen may cause a loss of appetite and weight.

Swollen Lymph Nodes — Lymph nodes under the arms, in the groin, chest and neck may become swollen when leukemia cells collect in the nodes. 

Difficulty Breathing — With one form of acute lymphocytic leukemia, leukemia cells tend to clump together around the thymus gland. This mass of cells present in the middle of the chest can cause pain and difficulty breathing. Wheezing, coughing or painful breathing requires immediate medical attention.

How is leukemia diagnosed in children?

• Taking a very careful history and performing a thorough physical examination are crucial first steps in making a diagnosis of leukemia.
  
  
• Your child’s doctor will perform an exam to check for signs of infection, anemia, abnormal bleeding, and swollen lymph nodes. The doctor will also feel your child’s abdomen to see if there is an enlarged liver or spleen.
  
  
• After this exam, the doctor will order a CBC (complete blood count) to measure the numbers of white cells, red cells, and platelets in your child’s blood. A blood smear will also be examined under a microscope to check for certain specific types of abnormal blood cells that are typically seen in patients with leukemia.
  

Then, depending on the results of your child’s physical exam and preliminary blood tests, your child may need the following:

• a bone marrow biopsy and aspiration, in which marrow samples are removed from the body (usually from the back of the hip) for testing
• a lymph node biopsy, in which lymph nodes are removed and examined under a microscope to look for abnormal cells
• a lumbar puncture (spinal tap), where a sample of spinal fluid is removed from the lower back and examined for evidence of abnormal cells. This will show whether the leukemia has spread to the central nervous system (brain and spinal cord).
• Bone marrow or lymph node samples will be examined and additional testing will be done to determine the specific type of leukemia. In addition to these basic lab tests, cell evaluations are also generally done, including genetic studies to distinguish between specific types of leukemia, as well as certain features of the leukemia cells.

How is leukemia treated in children?

Treatment for acute leukemia can include chemotherapy, steroids, radiation therapy, intensive combined treatments (including bone marrow transplants), and growth factors.

Certain features of a child’s leukemia, such as age and initial white blood cell count, are used in determining the intensity of treatment needed to achieve the best chance for cure.

Although all children with ALL are treated with chemotherapy, the dosages and drug combinations may differ.

To decrease the chance that leukemia will invade the child’s central nervous system, patients receive intrathecal chemotherapy, the administration of cancer-killing drugs into the cerebrospinal fluid around the brain and spinal cord.

Radiation treatments, which use high-energy rays to shrink tumors and keep cancer cells from growing, may be used in addition to intrathecal chemotherapy for certain high-risk patients.

After treatment begins, the goal is remission of the leukemia (when there is no longer evidence of cancer cells in the body). Once remission has occurred, maintenance chemotherapy is usually used to keep the child in remission.

Maintenance chemotherapy is given in cycles over a period of 2 to 3 years to keep the cancer from reoccurring.

Leukemia will almost always relapse (reoccur) if this additional chemotherapy isn’t given. Sometimes the cancer will return in spite of maintenance chemotherapy, and other forms of chemotherapy will then be necessary.

Sometimes a bone marrow transplant may be necessary in addition to - or instead of - chemotherapy, depending on the type of leukemia a child has. During a bone marrow transplant, healthy bone marrow is introduced into a child’s body.

Intensive leukemia chemotherapy have certain side effects, including hair loss, nausea and vomiting in the short term, and potential health problems down the line. As your child is treated for leukemia, your child’s cancer treatment team will monitor the child closely for those side effects.

Survival Rates of ALL

• About 98 to 99 percent of children with newly diagnosed acute lymphoblastic leukemia attain initial complete remissions (absence of detectable leukemic cells by microscopic examination) in four to six weeks.
• About 80 percent of children can be cured (patients who remain leukemia-free for 10 years or more can be considered cured).

Are there certain factors that affect chance of recovery?

The prognosis (chance of recovery) and treatment options depend on:

1. Age and white blood cell count at diagnosis.
2. How quickly and how low the leukemia cell count drops after initial treatment.
3. Gender and race.
4. Whether the leukemia cells began from the B lymphocytes or the T lymphocytes.
5. Whether there are certain changes in the chromosomes of lymphocytes.
6. Whether the leukemia has spread to the brain and spinal cord.
7. Whether the child has Down syndrome.