Comprehensive Review Raises Substantial Concern That Vaping May Increase Cancer Risk Over Time
核心洞察
A large scientific review published in Carcinogenesis finds that e-cigarette aerosols can damage DNA, trigger chronic inflammation, and contain carcinogenic compounds including formaldehyde, acetaldehyde, and heavy metals.
The review synthesized evidence from laboratory, animal, human biomarker, and epidemiologic studies, concluding that vaping is "not benign" and could increase cancer risk over time.
Authors caution that long-term population data is lacking since e-cigarettes have only been widely used for about a decade and cancers take decades to develop.
A newly published comprehensive review in the journal Carcinogenesis has raised substantial concerns that nicotine-based e-cigarettes may increase the risk of certain cancers, challenging the widespread perception that vaping is a benign alternative to combustible tobacco. The review, which synthesized findings from laboratory studies, animal studies, human biomarker studies, and epidemiologic research, concluded that the consistency of evidence across multiple study types warrants serious attention.
Dr. Leana Wen, an emergency physician and adjunct associate professor at George Washington University and former Baltimore health commissioner, discussed the findings in an interview with CNN, providing expert interpretation of the review's significance for public health.
Evidence of DNA Damage and Carcinogenic Compounds
The review summarized evidence demonstrating that e-cigarette aerosols can damage DNA and trigger chronic inflammation — both processes closely associated with cancer formation. Researchers identified potentially carcinogenic compounds in vaping aerosols, including formaldehyde, acetaldehyde, and heavy metals such as nickel, chromium, and lead, which may originate from heating elements within the devices.
Furthermore, the review examined evidence suggesting possible associations between vaping and cancers involving the lungs, mouth, and bladder. The authors noted that while nicotine is not considered a classic carcinogen in the same category as tobacco smoke, it may promote tumor growth, blood vessel formation, and cellular signaling pathways that support cancer progression.
"Many people assume that because e-cigarettes do not involve combustion, they are essentially harmless. It is true that vaping generally exposes users to fewer toxic chemicals than traditional cigarettes. But fewer harmful chemicals does not mean no harmful chemicals," Dr. Wen explained.
Mechanisms of Potential Harm
E-cigarettes heat liquid solutions that often contain nicotine, flavoring chemicals, and solvents such as propylene glycol and vegetable glycerin. When these substances are heated, they can break down into compounds that may damage cells and DNA. The aerosol generated by vaping devices also contains ultrafine particles that can be inhaled deep into the lungs, causing chronic inflammation.
Critical Limitations Acknowledged
The review authors were careful to note the limitations of the current evidence base. E-cigarettes have only become widely used over the last decade or so, and many cancers take decades to develop. This means researchers do not yet have the kind of long-term population data that definitively quantifies cancer risk in the way that exists for traditional cigarettes. Many of the existing studies are laboratory-based, involve animals, or examine short-term biological changes rather than actual cancer diagnoses in humans.
Still, taken together, the authors concluded that the consistency of findings across many different types of studies raises substantial concern that vaping is not benign and could increase cancer risk over time.
Safer Does Not Mean Safe
Dr. Wen emphasized that while vaping is probably less harmful than smoking combustible cigarettes — which contain thousands of chemicals including dozens of known carcinogens and remain one of the leading preventable causes of death worldwide — the distinction between "safer" and "safe" is critical.
"I worry that 'safer than cigarettes' is often interpreted as 'safe,' and that is not supported by the evidence," Dr. Wen said. "Vaping exposes users to nicotine, which is an addictive substance, and a range of potentially harmful substances. Vaping can exacerbate respiratory problems in people with asthma and other chronic lung conditions."
This distinction is especially important for adolescents and young adults who may never otherwise have smoked cigarettes. "For someone who does not smoke, starting to vape is never a good health-promoting choice," Dr. Wen stated.
The Dual Use Problem
The review also highlighted concerns about "dual use" — individuals who continue smoking cigarettes while also vaping. A number of studies have suggested that dual users can have cardiovascular and respiratory risks similar to or even higher than the harms seen with smoking alone. Complete smoking cessation should remain the goal, Dr. Wen advised.
Youth Vaping: A Persistent Public Health Challenge
More than 1.6 million U.S. middle and high school students reported current e-cigarette use in 2024, according to the U.S. Centers for Disease Control and Prevention (搜索). Many reported frequent use, and flavored products remain especially popular among youth.
Adolescents and young adults are a major concern because nicotine can affect the developing brain, particularly areas involved in attention, learning, and impulse control. Evidence also exists that vaping among youth is associated with increased likelihood of later cigarette smoking and other substance use, as well as associations with mental health conditions such as depression.
Smoking Cessation: Evidence-Based Alternatives
Dr. Wen noted that e-cigarettes are not approved by the U.S. Food and Drug Administration (搜索) as smoking cessation devices. FDA-approved alternatives with stronger evidence include nicotine replacement therapies such as patches, gums, lozenges, inhalers, and nasal sprays, as well as prescription medications varenicline and bupropion, which can significantly improve quit rates when combined with behavioral counseling and support programs.
"For people who smoke cigarettes and want to quit, I recommend that they discuss a structured cessation program with their clinician and use evidence-based methods approved by the FDA rather than relying on commercial vaping products that are not approved for smoking cessation," Dr. Wen said.
For current vapers who never smoked cigarettes, the advice is clear: consider reducing and ideally stopping use. For smokers who switched completely from cigarettes to vaping, the situation is more nuanced — it is preferable to vape rather than smoke cigarettes, but the long-term goal should ideally be freedom from nicotine addiction altogether.