A sweeping review of more than 100 scientific studies has concluded that nicotine-based e-cigarettes are likely to cause lung and oral cancer.

Published Monday in the journal Carcinogenesis, the landmark review was led by researchers at the University of New South Wales (UNSW) in Australia. Unlike many earlier studies that compared vaping to smoking, this one examined whether e-cigarettes cause cancer on their own.

The team, drawn from fields including pharmacy, epidemiology, thoracic research, and public health, reviewed peer-reviewed studies published between 2017 and 2025. Their analysis covered human clinical data, animal experiments, and laboratory research.

Bernard Stewart, an adjunct professor and cancer researcher from UNSW's Paediatrics and Child Health discipline, said the evidence of pre-cancerous cellular change was impossible to dismiss. "There is no doubt that the cells and tissues of the oral cavity, the mouth and the lungs are altered by inhalation from e-cigarettes," he told newsGP. "We're able to determine that in humans, there is unequivocal pre-carcinogenic change as a consequence of vaping."

Co-author and epidemiologist Freddy Sitas, an associate professor at UNSW, pointed to the urgency of acting on those early signals. "Early reports linked smoking to infectious diseases such as tuberculosis, followed by cardiovascular disease, stroke, and lung cancer," he said. "E-cigarettes were introduced about 20 years ago. We should not wait another 80 years to decide what to do."

One of the study's most alarming findings concerns people who both vape and smoke. A 2024 study found a four-fold higher risk of lung cancer among individuals who vaped and smoked compared to those who only smoked. Sitas warned that many people who begin vaping to quit smoking end up doing both. "Unless there is a proven device to stop people from vaping, then we're stuck in this high-risk population that starts using both," he said.

Stewart and Sitas acknowledge that the exact cancer risk from vaping cannot yet be quantified — that will require large-scale, long-term population studies that take years to complete. In the meantime, the researchers say their findings should help governments tighten regulations around vaping, particularly given a surge in use among young people.

"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," Stewart said. "Considering all the findings — from clinical monitoring, animal studies, and mechanistic data — e-cigarettes are likely to cause lung cancer and oral cancer."