Debra Wood, RN
and Michael Jubinville, MPH
Cancer is a disease in which cells grow in an abnormal way. Normally, the cells divide in a controlled manner to replace old or damaged cells. With leukemia, blood cells begin to develop abnormally and rapidly divide creating more blood cells than needed. These cells develop in the bone marrow, but will eventually travel throughout the body in the bloodstream. The abnormal blood cells do not function as normal blood cells. They also crowd out normal cells, which can lead to problems with the immune system, oxygen delivery, and blood clotting.
All blood cells start as stem cells that are formed in bone marrow. Stem cells can mature into a variety of different blood cell types that have specific functions in the body. These include:
New, healthy cells are developed in the bone marrow to replace old or damaged cells. This ensures there is a consistent number of blood cells in the body. With leukemia, there is an excessive development of new, abnormal blood cells. The abnormal cells crowd the bone marrow, making it difficult for new, healthy cells to develop. The abnormal cells and the lower levels of healthy cells lead to a weakened immune system, problems problems with oxygen delivery, or problems controlling bleeding depending on the type of blood cells that are affected. Cancerous blood cells also circulate in the blood and lymph systems, affecting organs like the spleen, liver, brain, and lymph nodes.
The instruction for cell growth and cell death exists in the DNA of each cell. Leukemia is the result of damage to DNA. The damage may be the result of genetics, environmental factors like radiation exposure, changes related to age, or a combination of these factors.
Leukemia is distinguished by how fast the leukemia develops and the type of blood cell that is affected. Leukemia may be distinguished as:
Leukemia is also distinguished by the type of bone marrow cells that is starts in:
Common types of leukemia include:
Acute lymphoblastic leukemia/lymphoma (ALL). EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 21, 2015. Accessed February 1, 2016.
Acute myeloid leukemia (AML). EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 31, 2015. Accessed February 1, 2016.
Chronic lymphocytic leukemia (CLL)/small lymphocytic leukemia (SLL). Available at: http://www.ebscohost.com/dynamed. Updated November 5, 2015. Accessed February 1, 2016.
Chronic myeloid leukemia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 19, 2015. Accessed February 1, 2016.
Leukemia. Leukemia & Lymphoma Society
website. Available at:
http://www.lls.org/leukemia. Accessed February 1, 2016.
Leukemia—patient version. National Cancer Institute
website. Available at:
http://www.cancer.gov/types/leukemia. Accessed February 1, 2016.
Overview of leukemia. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/hematology-and-oncology/leukemias/overview-of-leukemia. Updated October 2014. Accessed February 1, 2016.
Last reviewed December 2015 by Mohei Abouzied, MD
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