The findings revealed that compared to continuous smokers, complete quitters had a lower risk of cancer across all sites, with hazard ratios (HRs) of 0.83 for all cancers, 0.58 for lung, 0.73 for liver, 0.86 for stomach, and 0.80 for colorectal cancers. The cancer risk was slightly higher for the first 10 years after quitting compared to continued smoking but gradually decreased over time. After 15 years or more, the risk reached 50% of that associated with continued smoking.
Notably, lung cancer risk decreased three years earlier than other cancer types, demonstrating a larger relative reduction. The significant reduction in lung cancer risk was observed regardless of the age at quitting, but quitting before the age of 50 showed a greater reduction in lung cancer risk (HR 0.43) compared to quitting at age 50 or later (HR 0.61).
After ten years of quitting the cancer risk reduction is more significant
The study indicated that sustained smoking cessation is associated with a significantly reduced risk of cancer, particularly after 10 years since quitting. While early cessation, especially before middle age, was linked to a substantial risk reduction. These findings contribute valuable insights into the temporal aspects of cancer risk reduction following smoking cessation, providing evidence for the long-term benefits of quitting smoking in preventing various types of cancers.
While looking at the other side of the coin, another recent Cancer Research study explored the impact of smoking and vaping on DNA changes associated with cancer development. The research team claimed that despite the perception of vapes being less harmful than cigarettes, they found that vapes may also cause DNA damage linked with cancer.
Another study reported finding cancer-related epigenetic changes from vaping
The study focused on identifying biomarkers indicative of cancer risk that could be modified by tobacco smoking and e-cigarette use. Specifically, it investigated DNA methylation, an epigenetic modification associated with smoking-related diseases and cancer risk.
Using samples from over 3,500 individuals across Europe, the study analyzed DNA methylation patterns in different cell types and tissues exposed to cigarettes and vapes. It reported that both products use induced similar DNA methylation changes associated with carcinogenesis. These changes were observed in epithelial cells, which are key targets for tobacco-related malignancies, and the researchers reported that some of these alterations were also observed in vapers with limited smoking history.
So can vaping cause cancer? We consulted with an expert
Curious about these findings, we discussed them with smoking cessation expert and researcher, Dr. Colin Mendelsohn. He redirected us to an article on Science Media Centre which shared varied expert reactions and opinions.
Dr. Mangesh Thorat from Queen Mary University of London acknowledged the association between epigenetic alterations and cancer risk but highlighted the absence of a clear dose-response relationship. He suggested that these changes could simply reflect a general response to stress rather than increased cancer risk.
Associate Professor George Laking from the University of Auckland emphasized the importance of framing risk discussions accurately. He pointed out that while vapers exhibited some hypermethylation similar to smokers, there were also distinct differences. Laking underscored the complexity of cancer development and cautioned against overinterpreting early cellular changes.
“The authors of this study write that ‘despite widespread endorsement by Public Health England, who have advocated e-cigarettes as ‘95% less harmful’ than combustible cigarettes, recent studies have highlighted potential drawbacks’. A finding of drawbacks would not in itself be a ‘despite’ – it can still be compatible with the ‘95% less harmful’ figure, that also means ‘5% harmful,” said Laking.
Prof. Ross Lawrenson from the University of Waikato highlighted the need for evidence linking vaping to cancer incidence. He explained that while the study suggested epigenetic changes in e-cigarette users’ cheek lining, it lacked direct evidence linking these changes to cancer risk.
Similarly, Prof. Peter Shields from Ohio State University noted the study’s limitations in assessing vaping/smoking overlap and establishing causality. He highlighted the need for more refined data and cautioned against drawing adverse effect conclusions without biochemical verification and dose-response assessments. Shields suggested that the data may imply that vapers are more similar to never-smokers, implying a potentially lower cancer risk compared to smokers.
In summary, the above expert opinions as well as others included in the Science Media Centre article, all seem to agree that while the study provides valuable insights, caution needs to be exercised in interpreting the findings. The experts emphasized the importance of further research to understand the health implications of vaping compared to smoking.
Do not throw away your vapes just yet
Mendelsohn also shared a response from Cancer Research UK which explained that the study does not show that vaping causes cancer as it examined a different kind of cellular changes, not DNA mutations, and did not determine the implications of these changes for health. The group highlighted that vaping is not without risks, and non-smokers, especially children, should avoid it. However, research consistently suggests that legal vaping is significantly less harmful than smoking and can aid smoking cessation efforts.
Large Study by US Cancer Center Validated E-Cigarettes as Smoking Cessation Aids
