Exposure to high levels of radiation and certain chemicals are the main risk factors we know about for leukemia, particularly acute myeloid leukemia (AML). Our researchers have led efforts to identify many genes that are associated with the disease and that can guide us in selecting the most-effective treatment.

Specific risk factors for leukemia include:

• Exposure to cancer-causing agents. People exposed to high doses of radiation (from the explosion of an atomic bomb, working in an atomic weapons plant, or a nuclear reactor accident) have a heightened risk of developing leukemia. Long-term exposure to high levels of solvents such as benzene — in the workplace, for example — is a known risk factor. CLL may also be linked to exposure to Agent Orange, a chemical used widely during the Vietnam War.
• Smoking. Cigarettes contain dozens of cancer-causing chemicals. Researchers estimate that about 20 percent of AML cases are related to smoking.
• History of radiation therapy or chemotherapy. Radiation therapy and chemotherapy can cause mutations, or changes in a cell’s DNA, that later may lead to cancers including leukemia. AML is linked to treatments for Hodgkin’s disease, non-Hodgkin lymphoma, childhood ALL, and other malignancies such as breast cancer, and ovarian cancer.
• Myelodysplastic syndromes. About one-third of patients who have this bone marrow failure disorder may eventually develop leukemia. Learn more about MDS.
• Rare genetic syndromes. People with Down syndrome, Fanconi anemia, ataxia-telangiectasia, and Bloom syndrome are at slightly higher risk for developing leukemia.
• Family history. People who have a first-degree relative — a parent, child, or sibling — with CLL have a two- to four-fold increased risk of developing CLL. Most people who develop leukemia, however, do not have a relative with the disease.

Many people with one or more of these risk factors never develop leukemia. In fact, most people who develop leukemia have no known risk factors.