Leukemia is a cancer of the blood and bone marrow, where abnormal blood cells grow uncontrollably, crowding out healthy cells and impairing the body’s ability to fight infection, carry oxygen, and form clots. Smoking significantly increases the risk of developing certain types of leukemia.
Establishing the Link
Scientific research consistently demonstrates that tobacco use is a proven risk factor for leukemia. The harmful chemicals in tobacco smoke enter the bloodstream and spread throughout the body, reaching various tissues and organs. Studies indicate that individuals who smoke have a notably higher risk of developing leukemia compared to those who have never smoked.
The Biological Mechanism
Cigarette smoke contains over 7,000 chemicals, with at least 70 identified as carcinogens. When inhaled, these chemicals are absorbed through the lungs and enter the bloodstream. Benzene, a particularly harmful chemical in cigarette smoke, is present and known to be absorbed into the bone marrow. There, these substances can cause damage to the DNA within blood-forming stem cells. This DNA damage can lead to mutations and interfere with normal cell growth and differentiation, resulting in the uncontrolled proliferation of abnormal blood cells, a characteristic feature of leukemia.
Specific Leukemia Types and Related Exposures
Specific Leukemia Types
Acute Myeloid Leukemia (AML) is the type of leukemia most strongly and consistently linked to smoking; active smokers can have up to a 50% higher risk of developing AML compared to non-smokers. While the association is most pronounced for AML, some research also suggests a link between smoking and Chronic Lymphocytic Leukemia (CLL). However, the evidence for other leukemia types, such as Acute Lymphoblastic Leukemia (ALL), is less established or shows a weaker connection in adults.
Secondhand Smoke
Beyond direct smoking, exposure to secondhand smoke also poses a risk. Secondhand smoke contains many of the same carcinogens as direct smoke, and there is no safe level of exposure. It can increase the risk of leukemia, particularly in children.
Other Tobacco Products
Smokeless tobacco contains numerous carcinogens, but the current evidence does not strongly support a direct causal link to leukemia, although it is definitively linked to other cancers. The long-term health effects of vaping are still being studied, but e-cigarette aerosols contain chemicals that can cause DNA damage. Some studies have indicated a higher prevalence of leukemia among e-cigarette users compared to non-smokers.
Strategies for Risk Reduction
Quitting smoking is the most effective action individuals can take to lower their risk of smoking-related cancers, including leukemia. The risk of acute myeloid leukemia begins to decline once someone stops smoking. For those who have quit for 20 years or more, their risk is significantly reduced. Avoiding exposure to secondhand smoke is another important step to protect oneself and others from harmful chemicals. If someone has already been diagnosed with leukemia, quitting smoking can still offer benefits and may improve recovery outcomes.