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Cancer Health Center

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Leukemia - Topic Overview

Leukemia is cancer of the blood cells. It starts in the bone marrow, the soft tissue inside most bones. Bone marrow is where blood cells are made.

When you have leukemia, the bone marrow starts to make a lot of abnormal white blood cells, called leukemia cells. They don't do the work of normal white blood cells. They grow faster than normal cells, and they don't stop growing when they should.

Over time, leukemia cells can crowd out the normal blood cells. This can lead to serious problems such as anemia, bleeding, and infections. Leukemia cells can also spread to the lymph nodes or other organs and cause swelling or pain.

There are several different types of leukemia. In general, leukemia is grouped by how fast it gets worse and what kind of white blood cell it affects.

  • It may be acute or chronic. Acute leukemia gets worse very fast and may make you feel sick right away. Chronic leukemia gets worse slowly and may not cause symptoms for years.
  • It may be lymphocytic or myelogenous. Lymphocytic (or lymphoblastic) leukemia affects white blood cells called lymphocytes. Myelogenous leukemia affects the other type of cells that normally become granulocytes, red blood cells, or platelets.

The four main types of leukemia are:

There are less common leukemias, such as hairy cell leukemia. There are also subtypes of leukemia, such as acute promyelocytic leukemia (a subtype of AML).

Experts don't know what causes leukemia. Some things may increase your risk, such as being exposed to large amounts of radiation and being exposed to certain chemicals at work, such as benzene.

Symptoms may depend on what type of leukemia you have, but common symptoms include:

  • A new lump or swollen gland in your neck, under your arm, or in your groin.
  • Frequent nosebleeds, bleeding from the gums or rectum, more frequent bruising, or very heavy menstrual bleeding.
  • Frequent fevers.
  • Night sweats.
  • Bone pain.
  • Unexplained appetite loss or recent weight loss.
  • Feeling tired a lot without a known reason.
  • Swelling and pain on the left side of the belly.
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