Leukemia is a blood cancer that causes the bone marrow (the soft center of bones, where blood cells are made) to produce too many leukocytes. These abnormal white blood cells grow faster than healthy blood cells, eventually crowding them out. This leads to symptoms of leukemia, such as fatigue, infections, or easy bruising.

Leukemia is one of several types of blood cancer, including lymphoma, myeloma, myeloproliferative neoplasms, and myelodysplastic syndromes. This article explores possible causes and risk factors associated with leukemia, including genetic, environmental, and lifestyle factors.

How Do You Get Leukemia?

Like other cancers, leukemia is caused by genetic mutations (changes) that allow cells to divide and grow uncontrollably. There are two main types of mutations — inherited and acquired.

Acquired mutations:

• Happen during a person’s life, often due to aging or exposure to harmful substances
• Can be caused by high levels of radiation, certain chemicals, smoking, or some viruses
• Are found in the DNA of certain cells

Inherited mutations:

• Are passed down from parents to children
• Are present in the DNA of all cells at birth
• Occur far less often in leukemia

Most cases of cancer, including leukemia, are caused by acquired mutations. Often, doctors don’t know what causes these changes. Leukemia is rarely passed down in families, and most people with leukemia have no family history of blood cancer. However, some inherited genetic conditions can raise the risk of leukemia. At least 5 percent of leukemias may be linked to inherited mutations. Scientists are still studying why some people develop leukemia and others don’t.

How Do Cells Transform Into Cancer?

Normal cells divide in an organized way, making exact copies to replace old or damaged ones. Special genes in each cell control this process, signaling when cells should divide and when they should stop. Some genes even help find and fix DNA errors, and they can make a cell that has badly damaged DNA self-destruct instead of dividing.

If a genetic mutation turns off one or more of these genes in certain cells, those cells can start dividing faster. As mutations build up, the cells become more abnormal, growing out of control. Eventually, these disorganized cells may spread into nearby tissues or move to other parts of the body. When this happens, they have become cancerous.

What Are Leukemia Risk Factors?

It’s important to know that although science is good at finding relationships between factors and diseases, these links don’t always mean the factor causes the disease. Many risk factors for leukemia have been identified and are being studied to better understand how they might contribute to the disease.

Since genetic mutations cause leukemia, risk factors for leukemia include anything that might encourage these gene changes. Also, risk factors can vary depending on the type of leukemia.

Who Is Most Likely To Get Leukemia?

Anyone can get leukemia, but some groups are at higher risk. Most types of leukemia are more common in older adults, especially those over 65. However, acute lymphoblastic leukemia (ALL) is more common in children and young adults. Males have a slightly higher risk than females for most types of leukemia, according to City of Hope.

People with certain genetic disorders, a family history of leukemia, or previous exposure to chemotherapy or radiation therapy are also at increased risk.

Age

Mutations in DNA naturally build up. For cells that divide quickly, such as blood stem cells, researchers believe that tens of thousands of mutations may accumulate by the time a person turns 60. However, just a small percentage of people will develop cancer.

For most types of leukemia, a person’s risk increases with age. The median age at diagnosis is 65 for types such as acute myeloid leukemia (AML), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and chronic myeloid leukemia (CML).

The main exception is acute lymphoblastic leukemia, which is typically diagnosed in people under age 20. The median age for ALL diagnosis is 15.

Inherited Factors

You may be wondering, “Is leukemia genetic?” It’s uncommon for leukemia to be passed down in families, and most people with leukemia don’t have a family history of the condition. However, certain inherited traits and genetic disorders increase the risk of leukemia, especially childhood leukemia.

For example, having a brother or sister with leukemia slightly raises a child’s risk of acute leukemia. However, even for identical twins, the chance of the second twin developing childhood leukemia is only about 1 in 5.

Genetic Disorders

Certain genetic disorders can increase the risk of childhood leukemia. Examples include:

• Li-Fraumeni syndrome
• Down syndrome (also called trisomy 21)
• Neurofibromatosis type 1
• Fanconi anemia

Some inherited conditions that affect the immune system can also raise the risk of leukemia. These include:

• Wiskott-Aldrich syndrome
• Bloom syndrome
• Shwachman-Diamond syndrome
• Ataxia-telangiectasia

Sex, Gender, and Ethnicity

Leukemia affects people of all backgrounds, but some groups have higher rates. In general, leukemia occurs most often in non-Hispanic white people. Males also have a higher risk than females, accounting for 58.4 percent of new leukemia cases between 2016 and 2020, according to the Leukemia & Lymphoma Society.

Certain types of leukemia occur more often in some ethnicities, such as the following:

• ALL is more common in non-Hispanic white and Hispanic people.
• AML occurs more often in males than females.
• CLL/SLL is most common in males, especially in non-Hispanic white males.
• Childhood leukemia is most common in Hispanic people.

People from Asian, Pacific Islander, Native American, and Native Alaskan backgrounds generally have the lowest overall rates of leukemia​​.

What Environmental Factors Raise the Risk of Leukemia?

Anything that raises the risk of acquired genetic mutations also raises the risk of leukemia and other types of cancer. Several environmental factors and carcinogens (cancer-causing substances) are linked to leukemia.

Radiation

High doses of radiation exposure, including radiation therapy used for previous cancers, may increase leukemia risk for some people. Although some research suggests a possible link between long-term exposure to electromagnetic fields (such as those near power lines) and leukemia, especially ALL, scientists haven’t confirmed this. Current research is still inconclusive.

Chemicals

Frequent exposure to high levels of benzene is a possible cause of AML. This chemical is found in cigarette smoke, vehicle exhaust, and some industrial pollution. Prolonged exposure to certain pesticides has also been linked to an increased risk for some leukemia types. Past treatment with certain chemotherapy drugs for other cancers also can raise the risk of leukemia.

Obesity

Research indicates that obesity (a body mass index above 30) raises the overall risk of leukemia by 19 percent. The risk increases by leukemia type:

• ALL — 62 percent increased risk
• AML — 38 percent increased risk
• CLL/SLL — 17 percent increased risk
• CML — 27 percent increased risk

What Genetic Changes Are Linked With Leukemia?

Scientists have identified many genetic mutations in blood stem cells that can lead to leukemia. Some of these mutations are acquired, whereas others are inherited. Genetic testing on leukemia cells helps doctors identify these mutations, which can aid in the diagnosis of the type of leukemia and choosing effective treatments.

Can Leukemia Be Prevented?

There’s no certain way to prevent leukemia, especially in children. Most people who develop leukemia have no known risk factors. Most risk factors, including age, genetics, and ethnicity, can’t be controlled. If you’re concerned about your risk, you can take steps to address environmental factors, such as:

• Quit smoking, and avoid secondhand smoke.
• Limit exposure to radiation and harmful chemicals if you work with these substances. Use protective equipment and follow all safety guidelines.
• Follow general cancer prevention guidelines, such as eating a healthy diet with plenty of fruits, vegetables, and whole grains and limiting red and processed meats. A balanced, nutritious diet can also help you maintain a healthy weight.

If you have known risk factors for leukemia, follow up regularly with your doctor for monitoring tests. You may not notice symptoms right away, and early detection may mean additional treatment options and improved outcomes.

Talk With Others Who Understand

On MyLeukemiaTeam, the social network for people with leukemia and their loved ones, more than 20,000 members come together to ask questions, give advice, and share their stories with others who understand life with leukemia.

Are you living with leukemia? Have you and your doctor discussed your risk factors? Share your experiences in the comments below, or start a conversation by posting on your Activities page.