The exact cause of acute myeloid leukemia (AML) has not been identified. However, researchers have gained a greater understanding of how specific changes in DNA can cause bone marrow stem cells to develop into leukemia.

DNA is the genetic material that houses instructions for all of the body’s chemical processes. Some forms of cancer are caused by DNA mutations that “turn on” oncogenes (genes that speed up cell division) or “turn off” tumor suppressor genes (genes that slow down cell division or cause cells to die at the right time). In people with leukemia, these mutations are normally acquired after birth. The mutations may occur from exposure to radiation or cancer-causing chemicals, but many times the mutations occur for no apparent reason.

In addition, researchers have identified a number of factors that may make a person more likely to develop AML. These risk factors include:

• Smoking. Tobacco smoke contains cancer-causing substances that are absorbed by the lungs and spread through the bloodstream to numerous parts of the body.  It is especially risky for older adults, as smoking doubles the chances of developing AML in patients over 60.
  
  
• Chemotherapy. Patients treated for other cancers with certain chemotherapy drugs are at an increased risk of developing leukemia (secondary leukemia). These drugs are part of a class of drugs called alkylating agents and do not include all chemotherapy drugs.
  
  Recent studies have indicated that patients who receive higher-than-standard doses of two chemotherapy drugs (epirubicin and cyclophosphamide) have an increased risk of secondary leukemias, such as AML.
  
  AML is the most common form of secondary leukemia and usually occurs within 9 years after treatment. It most often develops after treatment for Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, and childhood acute lymphocytic leukemia (ALL). The risk is even greater if treatment uses both chemotherapy and radiation therapy. 
  
  
• Exposure to very high levels of radiation. Patients who have received radiation therapy as treatment for other forms of cancer have an increased risk of developing AML later in life. In addition, people exposed to radiation from atomic blasts (such as those in Japan during World War II) and nuclear accidents have an increased risk of developing AML.
  
  
• Benzene. Benzene is a colorless, flammable liquid used primarily as a solvent and a gasoline additive. It is also a component of cigarette smoke. Long-term exposure to the chemical can increase a person’s risk of developing AML.
  
  
• Gender. AML is more common in males than in females.
  
  
• Age. The disease most often occurs in older adults, and a person’s risk of developing AML increases with age. The average age of a person with AML is 65, and it rarely occurs before the age of 40. According to the American Cancer Society (ACS), a 50 year-old person’s chance of developing AML is 1 in 25,000. For a 70 year old person, the odds are 1 in 7,000.
  
  
• Obesity. Studies have indicated that individuals who are significantly overweight have an increased risk of developing myeloid leukemia. The incidence of myeloid leukemia was roughly five times higher among overweight and obese individuals than those with normal or low weight in a large study reported by the National Cancer Institute. Scientists believe that obesity may alter immune function. In addition, excess fat around the waist area may be related to chronic high levels of insulin and hormones that stimulate cell growth and inhibit cell death.
  
  
• Other blood disorders. People with certain blood disorders have an increased risk of developing AML. These disorders include:
  
  
• Myelodysplastic syndromes. Myelodysplastic syndromes (MDS) are conditions caused by abnormally developing cells of the bone marrow. Some physicians consider these syndromes pre-leukemia as approximately 30 percent of MDS cases evolve into AML.
  
  
• Polycythemia vera (an abnormal increase in the production of red blood cells).
  
  
• Thrombocythemia (an abnormal increase in the production of platelets).
  
  
• Genetic syndromes. People with certain genetic syndromes, such as Down syndrome, have an increased risk of developing AML.

Although acute myeloid leukemia may be associated with these risk factors, most patients with the disease have no known risk factors.