By Mikkael Sekeres, MD
Q: Can vaping cause cancer? And is vaping any safer than smoking traditional cigarettes?
The modern electronic cigarette, or e-cigarette, was invented in the early 2000s by a Chinese pharmacist in response to his father’s death from lung cancer. It was meant to be a nicotine-delivery device that was an alternative to traditional, tobacco cigarettes.
Since their introduction in Europe in 2006 and the United States in 2007, the use of e-cigarettes – a.k.a., vapes – has skyrocketed. The percentage of U.S. adults who used electronic cigarettes increased from 4.5 percent in 2019 to 6.5 percent in 2023, and sales from brick-and-mortar retailers jumped 34.7 percent, to over 21 million units, between February 2020 and June 2024.
According to the 2024 National Youth Tobacco Survey from the Centers for Disease Control and Prevention and the Food and Drug Administration, almost 6 percent of middle and high school students – 2.25 million children – reported using the devices in the past 30 days. The World Health Organization estimates that there are more than 16,000 flavors of e-cigarettes and that 88 countries do not require a minimum age to purchase.
But while they were introduced as a healthier and less carcinogenic option than tobacco cigarettes, the contents of e-cigarettes and their aerosols can contain harmful or potentially harmful substances that nobody should be eager to introduce to their bodies. These may include nicotine, heavy metals, particulate matter, propylene or diethylene glycol (found in antifreeze), diacetyl (linked to lung diseases), acrolein (an herbicide) and benzene (a known carcinogen).
A recent review from researchers in Australia found the results from laboratory investigations of e-cigarettes and their effects to be compelling enough to shift their recommendations from describing a need for more investigations to expressing frank concern about e-cigarette carcinogenicity.
That’s not something to take lightly. However, it’s important to note that the existing research does not definitively prove that vaping on its own (without smoking cigarettes currently or in the past) causes cancer in humans. While studies that have firmly established the link between tobacco smoking and multiple cancers have been conducted over the course of decades, studies focusing on e-cigarettes are still coming of age. E-cigarettes are still relatively novel and more popular among young adults. Presumably, younger people simply haven’t been smoking e-cigarettes long enough to develop cancer at high rates – yet.
However, research in animals and laboratory-grown cells, plus a handful of studies in humans, can give us a general idea of risk until more long-term research matures.
Here’s what we know – and still don’t know – about the connection between vaping and cancer.
Studies are still relatively sparse, but a few that have been conducted in laboratory-grown cells and mice suggest that vaping likely causes cellular changes that are associated with cancer development.
One study in mice showed that e-cigarettes delivered at the high-powered setting could cause damage to DNA in lung and liver cells, while studies of laboratory-grown breast cancer cells demonstrated that exposure to e-cigarettes increased levels of proteins in the cells that would make them more likely to metastasize and spread in mice.
Other laboratory studies have linked the liquid contents of e-cigarettes to growth and changes in squamous cell cancers found in the mouth, to the transformation of normal bladder cells into cancerous cells, and to brain tumor cell growth.
Again, these studies are compelling and their findings provide the rationale for additional research. But the results don’t always translate to humans, in part because they don’t perfectly mimic real-life use – for example, the lengths and concentrations of exposure used in mouse studies are not necessarily reflective of the average user’s puffs per day.
How vaping compares to cigarettes as a cancer risk
Unfortunately, here again the data are limited and imperfect but worrisome enough to be concerned that e-cigarette use may lead to cancer – perhaps not as strong a risk factor as traditional cigarettes, but certainly more than abstaining altogether.
For example, e-cigarettes can cause changes to chemicals in bodily fluids. In one small study that included 150 people, one-third smoked only tobacco cigarettes, one-third smoked only e-cigarettes, and one-third were non-smokers. Those who smoked tobacco cigarettes were more likely than the other two groups to have markers of inflammation associated with cancer risk in their saliva, but e-cigarette smokers still had higher levels of the markers than non-smokers.
One case report from China describes two patients who smoked e-cigarettes for more than a decade, but not tobacco cigarettes, who developed cancers of the mouth we would usually associate with long-term tobacco use.
In another study exploring e-cigarette use patterns in the U.S., among almost 120,000 participants, 1 percent reported current e-cigarette use, 5 percent past use, and over 500 people reported having a lung cancer diagnosis. Those with lung cancer were over two-and-a-half times more likely to use e-cigarettes than those without lung cancer, but it was not known if they adopted use after their cancer diagnosis or before. Further confounding the results, many also reported simultaneously using tobacco products.
There does appear to be a worrisome cancer risk when people vape and smoke cigarettes. In a study of more than 32,000 people, those who used e-cigarettes and tobacco cigarettes had four times the risk of developing lung cancer than those who smoked tobacco cigarettes alone. Their cancer risk was 40 times higher than those who didn’t smoke at all.
Similarly, in a preliminary population study from Korea that included more than 4 million people, over 50,000 people developed lung cancer. Those who stopped smoking tobacco cigarettes and took up e-cigarettes were 23 percent more likely to develop lung cancer than those who stopped smoking tobacco cigarettes but did not take up e-cigarettes.
In short, the data are accumulating and I suspect will become more definitive over the next few years in linking vaping to cancers of the lung, oral cavity and pharynx. Vaping is already linked to a potentially life-threatening condition known as EVAL1 (mostly associated with the delivery of THC in noncommercial vapes), a scarring condition known as bronchiolitis obliterans or “popcorn lung” and a higher risk of infections.
Some people do use e-cigarettes as a method of tobacco smoking cessation, and from what we can tell so far, e-cigarettes have not been tied to cancer in the way that tobacco smoking has. If possible, though, my advice is to try to kick the habit now, and discourage use in youth, before those studies come out.
Mikkael A. Sekeres, MD, MS, is the chief of the division of hematology and professor of medicine at the Sylvester Comprehensive Cancer Center, University of Miami. He is author of the books “When Blood Breaks Down: Life Lessons from Leukemia” and “Drugs and the FDA: Safety, Efficacy, and the Public’s Trust.”
(c) The Washington Post · Mikkael Sekeres, MD · HEALTH-FEATURES, SCIENCE
