Causes and Risk Factors for Leukemia
Leukemia is a group of cancers that begin in the blood-forming tissues, primarily the bone marrow. While the exact cause of any individual case is often unknown, research links a combination of genetic, environmental, and medical factors to a higher chance of developing the disease.
Key Takeaways
- Leukemia develops when DNA changes in blood-forming cells cause abnormal white blood cells to grow and multiply out of control.
- Recognized risk factors include older age, certain inherited genetic syndromes, and exposure to radiation or industrial chemicals such as benzene.
- Previous chemotherapy or radiation therapy given for another cancer can raise the risk of developing leukemia later in life.
- Most people diagnosed with leukemia have no identifiable risk factor, and having one or more risk factors does not mean the disease will develop.
- Recognizing these risk factors can help patients and doctors decide when closer monitoring or blood testing may be useful.
Exploring the Causes of Leukemia
Leukemia begins with acquired changes, or mutations, in the DNA of blood-forming cells, typically in the bone marrow. These mutations cause white blood cells to grow abnormally and multiply without maturing properly, crowding out healthy blood cells. According to MedlinePlus, the specific trigger for these genetic changes is often unknown, even though several factors are known to raise the likelihood that they occur.
Leukemia is rarely the result of a single cause. It typically develops from a combination of genetic predisposition and environmental exposure that disrupts normal cell growth and division. Some of the DNA changes involved are inherited, while others are acquired over a person’s lifetime.
Primary Risk Factors for Leukemia
While the exact cause of leukemia remains unclear in most cases, researchers have identified several factors associated with a higher likelihood of developing the disease. These risk factors do not directly cause leukemia, and having one or more of them does not mean a person will develop it — many people diagnosed with leukemia have no known risk factors at all.
Age and Gender
Acute lymphoblastic leukemia is the most common cancer diagnosed in children, making up close to a quarter of childhood cancer cases in the U.S., and it is diagnosed most often between ages 1 and 4. In adults, overall leukemia risk generally rises with age, and most diagnoses occur later in life. Sex also plays a role: men are somewhat more likely than women to develop leukemia, though the reasons for this difference are not fully understood.
Lifestyle Choices
Unlike many other cancers, lifestyle factors have a limited direct effect on leukemia risk. One clear exception is smoking, a well-established risk factor for acute myeloid leukemia; chemicals absorbed from tobacco smoke can damage the DNA of blood-forming cells. Maintaining a healthy weight and diet supports overall health, but has not been shown to meaningfully lower leukemia risk the way it can for some other cancers.
Genetic Predisposition to Leukemia
Some people inherit gene changes or syndromes that raise their leukemia risk from birth. These inherited conditions can affect how blood cells develop or how they repair DNA damage, making cells more prone to cancerous changes. Down syndrome, for example, is associated with a meaningfully higher risk of leukemia in childhood. Other inherited syndromes linked to increased leukemia risk include Fanconi anemia, Bloom syndrome, ataxia-telangiectasia, and neurofibromatosis type 1.
Most leukemia cases are not directly inherited and are not linked to a known family history. A smaller number of people carry an inherited predisposition, even without one of the syndromes above, that combines with other exposures to raise their risk. Researchers continue to study the specific genes involved in these inherited susceptibilities.
Environmental Factors Linked to Leukemia
Exposure to certain substances in the environment can raise the risk of developing leukemia. These exposures are among the more clearly identifiable, and in some cases avoidable, risk factors.
Ionizing Radiation Exposure
High-dose exposure to ionizing radiation is a recognized risk factor for leukemia. Sources of this exposure have included nuclear power plant accidents and the manufacture or testing of nuclear weapons. According to the National Cancer Institute, routine medical imaging such as chest X-rays and CT scans also involves ionizing radiation, but the cancer risk from these procedures is very small, and the health benefits of having them almost always outweigh that risk. Anyone concerned about cumulative exposure from repeated imaging can discuss this with their doctor.
Chemical Carcinogens
Exposure to certain industrial chemicals is another established leukemia risk factor. Benzene — found in gasoline, cigarette smoke, and some industrial solvents — is identified by the CDC as a cause of blood cancers, including leukemia. Workers in manufacturing and other industries with higher benzene exposure face a particular occupational concern, and protective measures can help lower this risk.
Medical History and Treatment Risks
A person’s medical history, including prior treatment for other conditions, can also affect their overall leukemia risk. Certain therapies and pre-existing blood disorders can alter the bone marrow environment in ways that raise the likelihood of leukemia developing later.
Previous Cancer Therapies
One of the most recognized medical risk factors is previous chemotherapy or radiation therapy given to treat another cancer, such as lymphoma or breast cancer. The National Cancer Institute lists this treatment history among the established risk factors for acute myeloid leukemia. The benefit of treating the original cancer typically outweighs this risk, but doctors monitor patients with this history for signs of a later leukemia diagnosis.
Certain Pre-existing Conditions
Myelodysplastic syndrome, a disorder in which the bone marrow produces abnormal blood cells, is considered a pre-leukemic condition because it can progress to acute myeloid leukemia in some patients. A personal history of myelodysplastic syndrome or a similar blood disorder is one of the recognized risk factors for leukemia.
Frequently Asked Questions
Can lifestyle changes prevent leukemia?
Lifestyle changes have a smaller direct effect on leukemia risk than they do for many other cancers. Avoiding known risk factors such as tobacco smoke and unnecessary benzene exposure may help lower risk, but many leukemia cases occur without any identifiable lifestyle cause.
Is leukemia always hereditary?
No. Most leukemia cases are sporadic, meaning they result from genetic changes acquired during a person’s lifetime rather than inherited ones. A smaller share of cases occur in people with an inherited syndrome, such as Down syndrome or Fanconi anemia, that raises their risk.
How do environmental factors contribute to leukemia?
Environmental exposures such as high-dose ionizing radiation and industrial chemicals like benzene can damage the DNA of blood-forming cells. This damage can lead to the mutations that allow leukemia to develop, though exposure alone does not guarantee that a person will get the disease.
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