Leukemia causes and risk factors

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on May 26, 2022.

Each year, approximately 60,000 people are diagnosed with leukemia. The risk of developing leukemia increases with age, but the disease may also develop in people under 20 years old.

What causes leukemia?

Leukemia develops when the DNA in blood cells called leukocytes mutate or change, disabling their ability to control growth and division. In some cases, these mutated cells escape the immune system and grow out of control, crowding out healthy cells in the bloodstream.

While patients may never know how they developed leukemia, since its exact cause is often not known, certain risk factors are linked to the disease, including exposure to radiation.

Risk factors that may cause leukemia

Gender: Men are more likely than women to develop leukemia.

Age: The risk of most leukemias increases with age. The median age of a patient diagnosed with acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) or chronic myeloid leukemia (CML) is 65 years and older. However, most cases of acute lymphocytic leukemia (ALL) occur in people under 20 years old. The median age of an ALL patient at diagnosis is 15.

Blood disorders: Certain blood disorders, including chronic myeloproliferative disorders such as polycythemia vera, idiopathic myelofibrosis and essential thrombocythemia increase the chances of developing AML.

Family history: Many wonder, Is leukemia hereditary? Most leukemias have no familial link. However, if the patient is a first-degree relative of a CLL patient, or if he or she has an identical twin who has or had AML or ALL, the patient may be at an increased risk for developing the disease.

Congenital syndromes: Some congenital syndromes including Down syndrome, Fanconi anemia, Bloom syndrome, ataxia-telangiectasia and Blackfan-Diamond syndrome seem to raise the risk of AML.

Smoking: Although smoking may not be a direct cause of leukemia, smoking cigarettes does increase the risk of developing AML.

Radiation: Exposure to high-energy radiation (e.g., atomic bomb explosions) and intense exposure to low-energy radiation from electromagnetic fields (e.g., power lines) may increase the risk for developing leukemia.

Chemicals: Long-term exposure to certain pesticides or industrial chemicals like benzene is considered a risk for leukemia.

Electromagnetic fields: Prolonged exposure, such as living near power lines, may increase a person’s risk for developing ALL.

Previous cancer therapy: Certain types of chemotherapy and radiation therapy for other cancers are considered leukemia risk factors.

Is leukemia preventable?

There is no confirmed way to prevent leukemia. Still, it may be possible to help reduce the risk for this type of cancer by making certain lifestyle changes and following healthy habits, including:

  • Don’t smoke. Current smokers should seek help to quit. There are lots of free cessation programs available online or in the local community. Keep trying and find what works.
  • Keep a healthy body weight. Lose weight if needed. Ask a doctor for advice on how to start a healthy weight loss program.
  • Avoid or lower exposure to chemicals that may raise the risk for leukemia, such as benzene and formaldehyde.
  • Lower any exposure to pesticides.
  • Stay physically active and follow a healthy diet. Both these lifestyle elements have been proven to reduce cancer risk in general.

Next topic: What are the symptoms of leukemia?

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