Vaping Likely Causes Cancer, Major Study Finds

Nicotine vaping is likely to cause lung and oral cancers, a comprehensive review of more than 100 studies has concluded.

According to the analysis, human and animal studies, as well as cell experiments looking at the effects of chemicals found in vape liquid, all point toward carcinogenicity. Those studies, published since 2017, record “increasing concern”, the researchers report.

We don’t have long-term, population-level data yet, so the exact risk cannot be quantified, but the early signs are strong enough that scientists are warning against repeating the mistakes made with cigarettes.

“Though smoking was once given the benefit of doubt,” write study co-authors Freddy Sitas and Bernard Stewart of the University of New South Wales in Australia in a related commentary, “the same should not now be accorded to vaping given the strength of relevant carcinogenicity data.”

Vaping emerged in the early 2000s, touted as a safer, less smelly delivery system for the addictive chemical nicotine than methods that involve inhaling the smoke of burning tobacco leaves. Instead, a device heats and vaporizes a nicotine-containing liquid, which the user then inhales.

Vaping’s popularity grew rapidly, with little information about the possible long-term damage vaping might cause.

Some public health experts nevertheless warned about the potential harms of vaping based on what was already known about the chemicals vapes contained.

Given that it took around 100 years – from the mid-1800s until 1964 – for scientists to prove a causal link between smoking and lung cancer, and another 50 years for the effects to be quantified, researchers remained on alert for new evidence as it emerged.

Yet studies often compared vaping to smoking or simply inferred a risk of cancer based on vapers tendencies to also smoke cigarettes.

Sitas, Stewart and colleagues wanted to assess “the carcinogenic impact of e-cigarettes in their own right”.

The team focused on studies that looked specifically at e-cigarettes or compared people who vape to those who don’t – excluding research that looked at dual users (who vape and smoke) or compared e-cigarettes to smoking. Their review also examined studies published since 2017 to avoid over-reliance on earlier, patchier work.

They categorized the studies into three main groups: human studies showing biomarkers of DNA damage, oxidative stress, and inflammation; experimental studies in mice showing the development of lung tumors as a direct result of vape aerosol exposure; and other lab analyses revealing the potential pathways via which compounds in vape liquid – including known carcinogens – inflict damage on cells.

The researchers also considered case reports describing heavy vapers presenting with aggressive oral cancers where traditional risk factors such as smoking or viral infection were absent or limited, including unusually severe disease in relatively young patients.

“To our knowledge, this review is the most definitive determination that those who vape are at increased risk of cancer compared to those who don’t,” says Stewart, a cancer researcher.