About 1.5% of people will be diagnosed with leukemia at some point during their lifetime. That means roughly 1 in 67 men and women will develop some form of the disease, based on data from the National Cancer Institute. In the United States alone, an estimated 62,770 new cases were expected in 2024. While that sounds like a large number, leukemia remains relatively uncommon compared to cancers of the breast, lung, or colon.
How Age Changes Your Risk
Leukemia is not one disease, and the risk doesn’t stay constant across your life. Some forms primarily affect children, while others are diseases of older adults. The overall incidence rate for adults between 25 and 84 is about 17.8 per 100,000 men and 10.5 per 100,000 women each year. That means men are roughly 70% more likely to be diagnosed than women in the same age range.
For children, the picture is different. Childhood leukemia is the most common cancer in kids, but it’s still rare in absolute terms. The types that appear in childhood, particularly acute lymphoblastic leukemia (ALL), have different causes and much better survival rates than the types that tend to develop later in life. The risk of most leukemia types climbs steadily after age 50, with the median age at diagnosis falling around 66.
The Four Main Types
Leukemia is split into four major subtypes, and each carries different odds and outcomes. ALL is the most common overall when all age groups are included, accounting for roughly 63% of cases in large epidemiological studies. Acute myeloid leukemia (AML) makes up about 24%, chronic myeloid leukemia (CML) about 10%, and chronic lymphocytic leukemia (CLL) around 2 to 10%, depending on the population studied. In Western countries, CLL tends to be more common among older adults than those numbers suggest, as detection rates vary widely by region.
The “acute” forms (ALL and AML) develop quickly and require immediate treatment. The “chronic” forms (CLL and CML) progress slowly and may not need treatment for years after diagnosis. This distinction matters because the type you’re at risk for depends heavily on your age, sex, and genetics.
Family History and Genetic Conditions
Having a first-degree relative (parent, sibling, or child) with a blood cancer raises your own risk, though the size of the increase varies by type. CLL risk jumps about 5.6-fold if a close relative has been diagnosed with it. AML risk increases about 1.5-fold with a family link. In practical terms, having an affected relative raises the cumulative lifetime risk of developing any blood cancer to roughly 4.3%, compared to 1.5% in the general population. That’s an increase of 1 to 2 percentage points, meaningful but not dramatic.
Certain genetic conditions carry much higher risk. Down syndrome is the most well-studied example. Children with Down syndrome face a 20-fold increased risk of ALL and a nearly 500-fold increased risk of AML before age 5, according to a large Swedish population study published in Nature. Virtually all AML cases in children with Down syndrome are diagnosed before their fifth birthday. Other inherited conditions that affect DNA repair or bone marrow function also raise leukemia risk, though they are far less common.
Smoking and Leukemia
Smoking is the most clearly established lifestyle risk factor for leukemia, particularly for AML. Current smokers have about a 50% higher rate of AML compared to people who have never used tobacco. Heavy smokers (more than 20 grams of tobacco per day) may face roughly double the risk of ALL as well, though the evidence for that link is less definitive. Smokeless tobacco, by contrast, does not appear to raise leukemia risk.
Body weight is a common concern, but the data here is reassuring. A large Swedish cohort study found no meaningful connection between being overweight or obese and developing any of the four main leukemia types. This sets leukemia apart from many solid-tumor cancers, where excess weight is a well-established risk factor.
Chemical and Radiation Exposure
Benzene is the best-known environmental cause of leukemia. Workers with sustained occupational exposure to benzene show a clear dose-dependent increase in risk. At moderate cumulative exposure levels, the risk of leukemia roughly doubles. At higher levels, the relationship steepens further. For most people, everyday exposure to benzene (from gasoline fumes, tobacco smoke, or industrial emissions) is far below occupational thresholds, but the risk is not zero. The connection is strong enough that benzene is classified as a known human carcinogen.
Previous cancer treatment is another significant risk factor. Radiation therapy alone raises the risk of developing a secondary leukemia by about 2.4 times. Certain chemotherapy drugs, particularly a class called alkylating agents, increase risk even more. When chemotherapy and radiation are combined, the relative risk climbs to about 17 times the baseline. That said, therapy-related leukemia is still uncommon in absolute terms. Among breast cancer patients treated with standard chemotherapy regimens, roughly 5 out of every 10,000 develop leukemia within ten years.
Putting the Numbers in Perspective
A 1.5% lifetime risk means that for every 100 people you know, between one and two will be diagnosed with leukemia at some point. Most of those diagnoses will come after age 60. If you have no family history, no significant chemical exposures, and don’t smoke, your personal risk is likely below that average. If you carry one or more risk factors, it may be somewhat higher, but even a 5-fold increase in a rare disease still translates to a small absolute number.
Survival has also improved substantially. While outcomes vary widely by type and age at diagnosis, the overall five-year survival rate for leukemia has risen sharply over the past several decades. Childhood ALL, once nearly always fatal, now has cure rates exceeding 90% in many treatment centers. CML, which was a death sentence 30 years ago, is now managed as a chronic condition for most patients thanks to targeted therapies. AML in older adults remains the most difficult to treat, but even there, newer approaches are extending survival.