Medically Reviewed by Minesh Khatri, MD on October 28, 2021
5 min read

Leukemia is a blood cancer caused by a rise in the number of white blood cells in your body.

Those white blood cells crowd out the red blood cells and platelets that your body needs to be healthy. The extra white blood cells don’t work right.

Different types of leukemia can cause different problems. You might not notice any signs in the early stages of some forms. When you do have symptoms, they may include:

No one knows exactly what causes leukemia. People who have it have certain unusual chromosomes, but the chromosomes don’t cause leukemia.

You can’t prevent leukemia, but certain things may trigger it. You might have a higher risk if you:

How does leukemia happen?

Blood has three types of cells: white blood cells that fight infection, red blood cells that carry oxygen, and platelets that help blood clot.

Every day, your bone marrow makes billions of new blood cells, and most of them are red cells. When you have leukemia, your body makes more white cells than it needs.

These leukemia cells can’t fight infection the way normal white blood cells do. And because there are so many of them, they start to affect the way your organs work. Over time, you may not have enough red blood cells to supply oxygen, enough platelets to clot your blood, or enough normal white blood cells to fight infection.

Leukemia classifications

Leukemia is grouped by how fast it develops and gets worse, and by which type of blood cell is involved.

The first group, how fast it develops, is divided into acute and chronic leukemia.

  • Acute leukemia happens when most of the abnormal blood cells don’t mature and can’t carry out normal functions. It can get bad very fast.
  • Chronic leukemia happens when there are some immature cells, but others are normal and can work the way they should. It gets bad more slowly than acute forms do.

The second group, what type of cell is involved, is divided into lymphocytic and myelogenous leukemia.

  • Lymphocytic (or lymphoblastic) leukemia involves bone marrow cells that become lymphocytes, a kind of white blood cell.
  • Myelogenous (or myeloid) leukemia involves the marrow cells that create red blood cells, platelets, and other kinds of white blood cells.

Types of leukemia

The four main types of leukemia are:


Your doctor will need to check for signs of leukemia in your blood or bone marrow. They might do tests including:

  • Blood tests. A complete blood count (CBC) looks at the number and maturity of different types of blood cells. A blood smear looks for unusual or immature cells.
  • Bone marrow biopsy. This test involves marrow taken from your pelvic bone with a long needle. It can tell your doctor what kind of leukemia you have and how severe it is.
  • Spinal tap. This involves fluid from your spinal cord. It can tell your doctor whether the leukemia has spread.
  • Imaging tests. Things like CT, MRI, and PET scans can spot signs of leukemia.

The treatment you get depends on the type of leukemia you have, how far it’s spread, and how healthy you are. The main options are:

Chemotherapy uses drugs to kill cancer cells in your blood and bone marrow. You can get the medicine:

  • Through a shot into a vein or muscle
  • As a pill
  • Into the fluid around your spinal cord

Radiation uses high-energy X-rays to kill leukemia cells or keep them from growing. You can get it all over or in only one part of your body where there are a lot of cancer cells.

Biologic therapy, also called immunotherapy, helps your immune system find and attack cancer cells. Drugs like interleukins and interferon can help boost your body's natural defenses against leukemia.

Targeted therapy uses drugs to block specific genes or proteins that cancer cells need to grow. This treatment can stop the signals that leukemia cells use to grow and divide, cut off their blood supply, or kill them directly.

A stem cell transplant replaces the leukemia cells in your bone marrow with new ones that make blood. Your doctor can get the new stem cells from your own body or from a donor. First, you'll have high doses of chemotherapy to destroy the cancer cells in your bone marrow. Then, you'll get the new stem cells through an infusion into one of your veins. They will grow into new, healthy blood cells.

Surgery. Your doctor can remove your spleen if it’s filled with cancer cells and is pressing on nearby organs. This procedure is called a splenectomy.

Show Sources


American Cancer Society: "Learn About Cancer (Detailed Guide): Leukemia -- Acute Lymphocytic," "Learn About Cancer: Leukemia -- Acute Myeloid (AML)," "Learn About Cancer: Leukemia -- Chronic Lymphocytic (CLL)," "Learn About Cancer: Leukemia -- Chronic Myeloid (CML)," "Learn About Cancer: Leukemia in Children."

National Cancer Institute: "Leukemia." "Adult Acute Myeloid Leukemia Treatment (PDQ)-Patient Version. Treatment Option Overview," "Chronic Lymphocytic Leukemia Treatment (PDQ)-Patient Version."

Leukemia & Lymphoma Society: "Leukemia."

Cancer.Net: "Understanding Targeted Therapy."

Mayo Clinic: "Leukemia: Treatments and drugs."

University of Texas M.D. Anderson Cancer Center: "Leukemia Treatment."

Cleveland Clinic: “Leukemia.”

American Association for Clinical Chemistry: “Leukemia.”

American Society of Hematology: “Leukemia.”

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