Robert Wood Johnson University Hospital
 

Leukemia

Pediatric Cancers - Leukemia

What is leukemia?

Leukemia is cancer of the blood and develops in the bone marrow. The bone marrow is the soft, spongy center of certain bones that produces the three major types of blood cells: white blood cells to fight infection; red blood cells that carry oxygen; and platelets that help with blood clotting and stop bleeding. When a child has leukemia, the bone marrow, for an unknown reason, begins to make new blood cells (usually white blood cells) that do not mature correctly, but continue to reproduce themselves. Normal, healthy cells only reproduce when there is enough space for them to fit. The body can regulate the production of cells by sending signals when to stop. With leukemia, these cells do not respond to the signals to stop and reproduce, regardless of space available.

These abnormal cells reproduce very quickly and do not function as healthy white blood cells to help fight infection. When the immature white blood cells, called blasts, begin to crowd out other healthy cells in the bone marrow, the child experiences the symptoms of leukemia (such as infections, anemia, or bleeding).

Who is affected by leukemia?

Leukemia is the most common form of cancer in childhood. It affects approximately 4,000 children each year in the U.S., accounting for about 35 percent of childhood cancers.

There are different types of leukemia. According to the American Cancer Society, acute lymphocytic leukemia (ALL) is the type of leukemia that most commonly affects children, most often between the ages of 2 and 4 years. Acute myelogenous leukemia (AML) is the second most common form of leukemia in children. AML generally occurs by the age of 2 years, and is not often seen in older children until the teenage years. AML is the most common type of acute leukemia in adults. The chronic forms of leukemia are rarely seen in children.

What causes leukemia in children?

The majority of childhood leukemias are acquired diseases. This means that gene mutations and chromosome abnormalities in cells occur sporadically (by chance) and are not inherited from a parent.

The immune system plays an important role in protecting the body from diseases, and possibly cancer. An alteration or defect in the immune system may increase the risk for developing leukemia. Children with inherited immune system problems and those who have had organ transplants (and take immune-suppressing drugs) are at increased risk for leukemia. Factors such as exposure to certain viruses, environmental factors, chemical exposures, and various infections have been associated with damage to the immune system, although it's not clear if they increase the risk of leukemia.

Children with certain genetic conditions, such as Down syndrome or Li-Fraumeni syndrome, are at increased risk of developing leukemia. With the exception of specific genetic syndromes, little is known about the causes of childhood leukemia.

What are the different types of leukemia?

There are three main types of leukemia in children:

The difference between lymphocytic and myelogenous is the stage of development on what is called the pluripotent stem cell. The pluripotent stem cell is the first stage of development of all of the blood cells (white blood cells, red blood cells, and platelets). This stem cell goes through stages of development until it matures into a functioning cell. The type of leukemia is determined by where the cell is in the stage of development when it becomes malignant, or cancerous.

The stem cell matures into either the lymphoid or myeloid cells. The lymphoid cells mature into either B-lymphocytes or T-lymphocytes. If the leukemia is among these cells, it is called acute lymphocytic leukemia (ALL). If the leukemia is found even further along this stage of development, it can be further classified as B-cell ALL or T-cell ALL. The more mature the cell, the more difficult it is to treat.

The myeloid cells develop into platelets, red blood cells, and specialized white blood cells, such as neutrophils and macrophages. There are many classifications of AML. The type of leukemia is determined by the stage of development when the normal cells become leukemia cells.

What are the symptoms of leukemia?

Because leukemia is cancer of the blood-forming tissue called the bone marrow, the initial symptoms are often related to irregular bone marrow function. The bone marrow is responsible for producing most of the body's blood cells, including the red blood cells, white blood cells, and platelets.

When leukemia occurs, the abnormal white blood cells (blasts) begin to reproduce very rapidly and begin crowding out and competing for nutrients and space with the other healthy cells. The following are the most common symptoms of leukemia. However, each child may experience symptoms differently. Symptoms may include:

With acute leukemia (ALL or AML), these symptoms may occur suddenly in a matter of days or weeks. With chronic leukemia (CML), these symptoms may develop slowly over months to years.

It is important to understand that the symptoms of leukemia may resemble other blood disorders or medical problems. These are common symptoms of the disease, but do not include all possible symptoms. Children may experience symptoms differently. Always consult your child's doctor for a diagnosis.

How is leukemia diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for leukemia may include:

Treatment for leukemia

Specific treatment for leukemia will be determined by your child's doctor based on:

Treatment usually begins by addressing the presenting symptoms such as anemia, bleeding, and/or infection. In addition, treatment for leukemia may include (alone or in combination) the following:

What are the various stages of leukemia treatment?

There are various stages in the treatment of acute leukemia, including the following:

Relapse may occur even with aggressive therapy. Relapse is when the bone marrow begins making abnormal cells again. Relapse can occur during any of the stages of treatment, or may occur months or years after treatment has ended.

Treatment for chronic myelogenous leukemia may begin with a targeted therapy drug, which is taken daily as a pill. These drugs are usually very effective at keeping the leukemia under control, but because they do not cure it and they must be taken continuously, the doctor may recommend a stem cell transplant, if one can be done.

Long-term outlook for a child with leukemia

Prognosis greatly depends on:

As with any cancer, prognosis and long-term survival can vary greatly from child to child. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential for the child diagnosed with leukemia.

Side effects of radiation and chemotherapy, as well as second malignancies, can occur in survivors of leukemia. New methods are continually being discovered to improve treatment and to decrease side effects of the treatment for the disease.

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