Leukemia Facts

What Is Leukemia?

Leukemia is a disorder involving blood cells. Healthy cells form in the bone marrow and mature into red blood cells—delivering oxygen and nutrients to the body’s tissues—white blood cells fight infections and platelets stop bleeding.

In patients with leukemia, these cells do not mature as they should, or they transform into irregular blood cells that do not function normally. As abnormal cells build up in the bone marrow and bloodstream, the patient may experience anemia, susceptibility to infections and bleeding that does not clot due to the lack of functional red blood cells, white blood cells and platelets.

 

Types of Leukemia

Generally, leukemia is classified by the types of cells affected (myeloid or lymphoid) and whether it is fast- or slow-growing (acute or chronic). As such, the four major subtypes of leukemia are:

  • Acute myeloid leukemia (AML) starts in the bone marrow (the soft inner part of certain bones, where new blood cells grow), but most often, it quickly moves into the blood. AML can sometimes spread to other areas, including the lymph nodes, liver, spleen, central nervous system (brain and spinal cord) and testicles. Learn more about our acute myeloid leukemia program.
  • Acute lymphocytic leukemia is also called acute lymphoblastic leukemia. Acute means it can progress quickly, and lymphocytic because it develops from early (immature) forms of lymphocytes, a type of white blood cell.
  • Myeloid leukemias (also known as myelocytic, myelogenous or non-lymphocytic leukemias) start in early myeloid cells — the cells that become lymphocytes, red blood cells or platelet-making cells (megakaryocytes).
  • Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. It's a type of cancer that starts in cells that become lymphocytes in the bone marrow. The cells start in the bone marrow and then enter the blood. In CLL, the leukemia cells often build up slowly. Many people won't show symptoms until after a few years. Meanwhile, the cells grow and spread over time to the rest of the body, including the lymph nodes, liver and spleen.

How Leukemia Develops

Cancers can be caused by DNA mutations that keep oncogenes turned on or off tumor suppressor genes can cause cancer. Chromosome translocation is a common type of DNA change that can lead to leukemia. Human DNA is packed into 23 pairs of chromosomes. In a translocation, DNA from one chromosome breaks off and attaches itself to a different chromosome. The point on the chromosome where the break occurs can affect oncogenes or tumor suppressor genes. This produces an oncogene called BCR-ABL, which helps the leukemia cells grow.

What Increases Your Risk of Leukemia?

Factors that can elevate the risk of leukemia include:

  • A personal or family history of leukemia or blood disorders
  • Prior treatment with radiation or chemotherapy
  • Exposure to radiation or certain chemicals, including benzene, formaldehyde and Agent Orange
  • Infections with specific viruses, such as the Epstein-Barr virus or human T cell lymphoma/leukemia virus (HTLV-1)
  • Being male
  • Smoking

Hereditary Causes of Leukemia

In some cases, children inherit DNA mutations from a parent, increasing their risk for cancer. Certain inherited conditions can heighten the risk of developing leukemia, but most childhood leukemias do not appear to result from inherited mutations. Usually, DNA mutations related to leukemia develop after conception. However, some of these acquired mutations might occur early, even before birth.

What Are the Symptoms of Leukemia?

Common symptoms associated with leukemia include:

  • Unexpected appetite loss or weight loss
  • Fatigue
  • Anemia
  • Frequent or long-lasting infections
  • Excessive bleeding and bruises, or bleeding that does not stop
  • Enlarged spleen or lymph nodes
  • Petechiae (flat, round and red pinpoint spots under the skin)
  • Shortness of breath
  • Fevers, chills and other flu-like symptoms
  • Night sweats

Although other conditions can cause these symptoms, you should check with a doctor — preferably a hematologist — to get a definitive diagnosis.

At City of Hope, our world-renowned clinical team performs leading-edge diagnostics to ensure the best outcomes for our leukemia patients.
 

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