The short answer
Known leukemia risk factors include high-dose radiation, long-term benzene exposure, some past chemotherapy drugs, certain genetic conditions, and older age. Most people diagnosed with leukemia have no identifiable risk factor at all.
Risk factors raise the odds of leukemia; they do not cause it in any one person and do not mean a diagnosis is coming.
Most people diagnosed with leukemia have none of the known risk factors, and most people with a risk factor never develop leukemia.
High-dose radiation, long-term benzene exposure, and certain past chemotherapy drugs are the clearest environmental and treatment-related risk factors.
Some genetic conditions, including Down syndrome, raise the risk of specific leukemia types, especially in children.
Choose how you want to understand this
The full explanation.
The simple version
A risk factor makes a disease somewhat more likely. It does not directly cause it in any one person. Most people diagnosed with leukemia have no known risk factor. And most people who do have a risk factor never develop leukemia. Risk factors also differ across the four main types.
Having a risk factor is not a diagnosis, and not having one does not rule leukemia out.
Factors linked to more than one type
- Age. Leukemia can happen at any age. But AML, CLL, and CML become more common as people get older. ALL is more common in young children and in adults over 50.
- Sex. All four main types are somewhat more common in men than in women, for reasons that are not fully understood.
- Radiation. High-dose radiation exposure raises the risk of AML, ALL, and CML. Sources include an atomic bomb, a nuclear reactor accident, or radiation treatment for another condition.
- Certain past chemotherapy. Some drugs used for an earlier cancer can raise the risk of AML or ALL years later. They include alkylating agents such as cyclophosphamide, and topoisomerase II inhibitors such as etoposide.
- Some genetic conditions. Down syndrome, Fanconi anemia, and Bloom syndrome raise the risk of AML or ALL. So do a few other inherited conditions. The effect is largest in children.
- Certain blood disorders. Myelodysplastic syndrome (MDS) can progress to AML in some people. So can some myeloproliferative disorders.
Factors specific to one type
AML: Long-term benzene exposure and smoking are established risk factors. Smoking is the only proven lifestyle-related risk factor for AML.
ALL: Long-term benzene exposure is linked to ALL. Two viral infections have documented links too. One is HTLV-1, a rare cause of T-cell ALL. The other is Epstein-Barr virus, linked to some ALL and to Burkitt lymphoma.
CLL: Risk rises if a first-degree relative has CLL. That means a parent, sibling, or child. Some studies link Agent Orange and long-term pesticide exposure to CLL, though more research is needed. In the United States, CLL is more common in White people than in other racial or ethnic groups. It is also more common in North America and Europe than in Asia.
CML: CML has the shortest list of known risk factors. Age and high-dose radiation are on it. Beyond those, the American Cancer Society states there are no other clear risk factors. Smoking, diet, chemical exposure, infections, and family history are not linked to CML risk.
What does not appear to matter
Electromagnetic fields, everyday pesticide exposure, hair dyes, and stress have not been conclusively linked to leukemia. That does not mean environment and genetics do not matter. It means current research has not established these particular links.
Living with this information
It is common to look for a reason after a diagnosis. For most people with leukemia, there isn't one to find. Risk factor lists exist to guide research. In a few cases they inform monitoring for people at higher risk. They are not there to assign blame.
Questions to ask
- Are there specific risk factors relevant to my history?
- Does my leukemia type have a genetic component my family should know about?
- Should any relatives be monitored because of my diagnosis?
- Did a past treatment raise my risk for this?
Sources
Words to know
Tap any term to see what it means.
Common questions
Did I do something to cause my leukemia?
Almost always, no. Most people diagnosed with leukemia have no identifiable risk factor, and lifestyle choices rarely explain why leukemia develops. Smoking is the one clearly proven lifestyle-related risk factor, and only for AML.
Can leukemia run in families?
It can happen more than once in a family, but this is uncommon for most types. A first-degree relative (parent, sibling, or child) with CLL raises risk somewhat. Most people with leukemia have no family history of it.
Does stress cause leukemia?
There is no established evidence that stress causes leukemia. Stress can affect how someone feels day to day, which matters on its own, but it is not a proven cause of blood cancer.
Is chronic myeloid leukemia linked to lifestyle at all?
Not that research has established. According to the American Cancer Society, CML risk does not appear to be affected by smoking, diet, chemical exposure, or infections, and family history is not linked to it either. Age and high-dose radiation exposure are the main known factors.
If I was treated with chemotherapy for another cancer, am I at risk for leukemia?
Certain chemotherapy drugs, including alkylating agents and topoisomerase II inhibitors, are linked to a higher risk of AML and ALL developing later, usually years after treatment. This is one reason survivorship follow-up includes blood tests. Ask your team whether your specific treatment history carries this risk.
Questions to ask your doctor
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Last updated: 2026-08-10Next planned review: 2027-08-03
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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