Leukemia is often thought of as a childhood cancer, though some types of this disease are more common in adults. Leukemia makes up about 25 percent of all cancers affecting children and almost 2200 children are diagnosed each year in the US.

What is Leukemia?

Leukemia is a cancer of the blood and the bone marrow where blood cells are made. Its name comes from the Greek words leukos or white and aima or blood. Leukemia generally affects the production of white blood cells which are important in germ-fighting immune cells.

In leukemia, cells do not replicate faster than normal cells, they proliferate without the normal checks and controls due to non-inherited changes in the DNA of immature blood cells. These faulty cells eventually crowd out normal cells and lead to defects in the production of all normal blood cells lines such as red blood cells and platelets. As these primitive or non-differentiated cells cannot perform the functions of healthy blood cells, a person with leukemia becomes very ill.

Symptoms stemming from decreased production of normal blood cells include fatigue, weakness, weight loss, shortness of breath, fever, easy bruising, joint pain and swelling, frequent nosebleeds and bleeding. Complications of leukemia include infection, anemia (low numbers of red blood cells) and hemorrhage (uncontrolled bleeding).

The causes of childhood leukemia is unknown, however this disease is more common in children with Down Syndrome and children exposed to radiation prenatally.

Types of Leukemias in Children and Adults

Leukemia in children and adults differ in the type of leukemia and how it progresses, as well as in the treatment and risks.

There are four main groups of leukemia, which may fall under acute or chronic disease. Acute leukemias are fast progressing diseases while chronic leukemias progress at a slower rate. Each of the four groups also has several subtypes of leukemia, depending on the specific blood cells that are involved.

• Acute Lymphocytic Leukemia (ALL) is the most common malignant disease in children occurring in over 60 percent of all childhood leukemias. It can affect adults as well, particularly in individuals over the age of 65 years. It is the most curable form of leukemia.
• Chronic Lymphocytic Leukemia (CLL) is the most common leukemia in adults, particularly those over the age of 55 years. It affects 60 percent more men than women and is extremely rare in children. Chronic leukemia is slow progressing and is thought to be incurable.
• Acute Myelogenous Leukemia (AML) is more common in adults than children, making up 60 percent of leukemia in adults and about 30 percent of childhood leukemia. More males are affected than females. This type may also be referred to as acute non-lymphocytic leukemia (ANLL).
• Chronic Myelogenous Leukemia (CML) commonly affects adults and is very rarely seen in children.

Cancer Treatment and Risks

The good news is that leukemia in children is responsive to treatment and the survival rate is a high 85 percent. The most common type in children, acute lymphoblastic leukemia, is treated with chemotherapy. In adults, leukemia is often treated with higher doses of chemotherapy as well as bone marrow transplants and radiation. Survival rates are lower in adults and there is a higher risk of infertility due to treatment. As children usually require less toxic treatment, side effects such as infertility are less common. Children will require continued, careful monitoring by a pediatric oncologist, a specialist in childhood cancer. Fortunately, with treatment, most children with leukemia survive without the disease recurring.