A study from University College London has found people who vape have similar changes to their DNA as smokers do.
These specific cheek cell changes are linked to smokers developing lung cancer later in life.
The study is an incremental step in helping researchers build a deeper understanding of the long-term effects of vaping.
First author, Dr Chiara Herzog said this was the first study to investigate the impact of smoking and vaping on different kinds of cells - rather than just blood.
"We cannot say that e-cigarettes cause cancer based on our study, but we do observe e-cigarette users exhibit some similar epigenetic changes in buccal cells as smokers, and these changes are associated with future lung cancer development in smokers," she said.
University of Auckland associate professor Kelly Burrowes said the long-term effects of vaping were still unknown.
Vapes had only widely available for 20 years, and it took more than 50 years before the connection between smoking and smoking-related diseases became clear, she said.
"It just feels like history is repeating itself," she said.
"With smoking, there were early signs that it might cause harm, but it wasn't until there were increases in people having lung cancer, and other diseases, that they could definitively link it together."
Lung cancer is the most deadly cancer in New Zealand, killing more than 1600 people every year.