Leukemia is the most common cancer in children. As a result, many people don't realize that it also affects adults. In fact, leukemia is most common in people older than 60.
The National Cancer Institute estimates that about 45,000 people were diagnosed with leukemia in 2009. Of those, around 10 percent were younger than 20. Almost 54 percent of them were age 55 or older.
What is leukemia?
Leukemia is a type of cancer that affects the blood-forming cells in the bone marrow. In leukemia, bone marrow produces abnormal white blood cells called leukemia cells. These cells don't function normally, and they don't die off as they should. Over time they crowd out normal white blood cells, red blood cells and platelets. This makes it hard for the blood to do its many jobs.
What are the types of leukemia?
Leukemia is classified by how quickly it progresses and by the type of blood cells it affects.
- Chronic leukemia gets worse slowly. It may not cause symptoms in its early stages. When symptoms start, they may be mild and gradually get worse.
- Acute leukemia progresses rapidly and requires quick, aggressive treatment.
- Lymphocytic leukemia occurs in the bone marrow cells that produce lymphocytes, white blood cells that are part of the body's immune system.
- Myelogenous leukemia occurs in myeloid cells, the bone marrow cells that produce red blood cells, some white blood cells and platelets.
The common types of leukemia in adults are:
- Chronic lymphocytic leukemia (CLL). This is the most common form of leukemia in adults. It is usually diagnosed after age 55. It is very rare in children.
- Acute myeloid leukemia (AML). This is the second most common type of leukemia in adults. It also occurs in children.
- Chronic myeloid leukemia (CML). This type affects mainly adults.
- Acute lymphocytic leukemia (ALL). This type can affect adults but is most often diagnosed in young children.
There are some other types of leukemia, such as hairy cell leukemia. But they are rare.
What increases the risk?
Experts are not sure what causes leukemia, but some things are known to raise the risk of developing this type of cancer. Some known risk factors include:
- Exposure to high levels of radiation, such seen in survivors of an atomic bomb explosion such as Hiroshima or Nagasaki.
- Long-term exposure to benzene, which is used in the making of many other chemicals. It is also found in tobacco smoke.
- Chemotherapy. Certain cancer-fighting drugs can lead to leukemia years later.
- Genetic disorders such as Down syndrome.
Having any of these risk factors does not mean a person will get leukemia. Most people who get leukemia have no known risk factors.
What are the symptoms?
Symptoms may vary depending on the type of leukemia and the number of leukemia cells in the body. However, some common symptoms include:
- Swollen lymph nodes (especially in the neck or armpit)
- Fever or night sweats
- Frequent infections
- Weakness and fatigue
- Easy bruising and bleeding
- Swelling or discomfort in the belly
- Unexplained weight loss
- Joint or bone pain
These symptoms have many possible causes besides cancer. But if you have any of these symptoms, see your doctor right away to find out what is causing them.
Created on 11/10/2006
Updated on 12/08/2010
- National Cancer Institute. What you need to know about leukemia.
- Leukemia and Lymphoma Society. Leukemia.
- Leukemia and Lymphoma Society. Leukemia facts and statistics.
- Landgren O, Albitar M, Ma W, et al. B-cell clones as early markers for chronic lymphocytic leukemia. New England Journal of Medicine. 2009;360(7):659-667.
- American Society of Clinical Oncology. Leukemia - chronic lymphocytic - CLL.