Leukemia

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/15/2026Status: primary verified

What is leukemia? Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job: White blood cells help your body fight infection Red blood cells deliver oxygen from your lungs to your tissues and organs Platelets help form clots to stop bleeding When you have leukemia, your bone marrow makes large numbers of abnormal cells. This problem most often happens with white blood cells. These abnormal cells build up in your bone marrow and blood. They crowd out the healthy blood cells and make it hard for your cells and blood to do their work. What are the types of leukemia? There are different types of leukemia. Which type of leukemia you have depends on the type of blood cell that becomes cancer and whether it grows quickly or slowly. The type of blood cell could be: Lymphocytes, a type of white blood cell Myeloid cells, immature cells that become white blood cells, red blood cells, or platelets The different types can grow quickly or slowly: Acute leukemia is fast growing. It usually gets worse quickly if it's not treated. Chronic leukemia is slow growing. It usually gets worse over a longer period of time. The main types of leukemia are: Acute lymphocytic leukemia (ALL) , which is the most common type of cancer in children. It can also affect adults. Acute myeloid leukemia (AML) , which is more common in older adults but can also affect children Chronic lymphocytic leukemia (CLL) , which is one of the most common types of leukemia in adults. It often occurs during or after middle age. Chronic myeloid leukemia (CML) , which usually occurs in adults during or after middle age What causes leukemia? Leukemia happens when there are changes in the genetic material (DNA) in bone marrow cells. The cause of these genetic changes is unknown. Who is at risk for leukemia? For the spe

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This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.