Cancer Risk and Nicotine: Separating Science from Sensationalism in the Vaping Debate

Research on nicotine, cancer risk, and reduced-risk products has been, once again, clouded by a wave of dubious science and magnified media narratives. A crux of this confusion is a chronic inability to separate the deleterious effects of combustion from the pharmacological actions of nicotine itself—two fundamentally distinct phenomena that should never, ever be conflated on serious public health terms.

An ever-increasing body of evidence continues to strengthen a vital point: The cancer risk from smoking is extremely significant. When tobacco is burned, it generates thousands of chemicals, including dozens of well-known carcinogens. Eliminate combustion, and the toxicological makeup changes dramatically. This is the rationale behind tobacco harm reduction — and it is a principle backed by decades of scientific evidence.

But there has been a very recent effort in the literature to obscure this distinction, including the title of a widely publicised review in Carcinogenesis that suggested vapes could be carcinogenic. Such claims have attracted immediate and sharp criticism from prominent researchers, such as Peter Hajek and Lion Shahab, whose different concerns focused on major methodological and interpretative flaws.

At the core of the critique is a bedrock scientific principle: dose matters. Modern analytical techniques can detect tiny traces of chemicals — often at levels so low they pose no meaningful health threat. At best, we give the misleading impression that being present alone is evidence of carcinogenicity, without providing any perspective on levels of exposure. As Hajek points out, a number of the studies on which these reviews draw depend on unrealistic laboratory conditions, such as overheating e-liquids to levels that do not match normal vaping behaviour.

More importantly, these reviews rarely mention the comparison that really matters — again, vaping versus smoking. When that comparison is drawn, the contrast is stark. Studies have consistently found that harmful and potentially carcinogenic compounds from vaping are just a small fraction of those associated with combustible cigarettes. Certain toxicants in cigarette smoke are not present in vapour.

Nicotine is not the enemy

These findings support earlier toxicological predictions, including those in Tobacco Control, which calculated the cancer potency of emissions from vapourized nicotine products to be several orders of magnitude lower than that from cigarette smoke. These findings aren’t controversial among scientists — they’re fundamental.

Just as significant is the constant misrepresentation of nicotine itself. Despite the public confusion, nicotine is not a carcinogen according to authorities like the International Agency for Research on Cancer. Though it is addictive, hence not without risk, its role in smoking-related disease is secondary to the delivery system — combustion.

Shahab’s critique of the Carcinogenesis review is even more scathing, pointing out that no common systematic review guidelines exist. Without clear inclusion criteria, pre-registered methodologies (which publicly state how a review will be undertaken), and transparent data selection, such reviews are particularly subject to bias. Effectively, their potential lies in moving into the realm of policy statements rather than evidence synthesis.

This issue is, of course, not isolated. A study published in 2025 raised suspicion that vaping was linked to multiple cancers, but was later retracted due to concerns about methodology. The retraction cited several major errors, including failure to report data consistently, reliance on previously retracted studies, and conclusions not supported by the evidence presented.

Changes made to the original protocol for the study, particularly those that permitted the inclusion of animal studies, non-peer-reviewed abstracts, and smoking-confounded data, introduced tremendous bias, wrote Arielle Selya. The lack of clear disclosures and justifications for these changes suggests a failure of integrity not just in the process but in the review itself.

Further complicating the problem are observational studies with basic design problems. A recent case-control report published in the journal Frontiers in Oncology, for instance, indicated a higher risk of cancer among people who smoked and vaped. But critics like Michael Siegel noted a classic case of reverse causation: people with early disease symptoms may switch to vaping to quit smoking. Such associations cannot establish causality without longitudinal data tracking behavior over time.

This distinction is critical. Cancer does not develop overnight; it takes years, if not decades. Studies that do not control for a history of smoking or the timing of product use “risk inferring causation when none exists.” Existing disease drives or changes behaviour — not the reverse is much more likely, Siegel writes.

Despite such major methodological issues, these findings are reported in absolute terms in headlines that often bolster public myths. This leads to a bigger problem: dubious research can influence public perception far before corrections or retractions occur. As Delon Human pointed out on Filter, misinformation travels much faster than its scientific correction, and once it’s out there, it can leave an impression that may be hard to unlearn. The sad truth is that when a sensationalized title makes it to the media, any retractions that follow never do, leading to a dangerous loop: policymakers respond to an increased perceived risk by imposing tighter regulations, and smokers are denied even low-risk options.

This is particularly disturbing because there is a wealth of evidence that suggests vaping should be used as a smoking cessation tool. Vapes are more successful than traditional nicotine replacement therapies at helping smokers quit, according to multiple independent reviews. By providing nicotine without burning, they satisfy the chemical dependence as well as behavioural aspects of smoking.

The public health ramifications are profound. When smokers switch entirely from cigarettes to vaping, they remove themselves from exposure to the first and second leading causes of smoking-related disease. Though not without risk, the reduction in relative risk is dramatic — and that difference should be central to any evidence-based policy debate.

Sadly, the ongoing debate is increasingly driven by what some experts call systemic bias against harm reduction. As Siegel points out, researchers are not immune to dominant narratives and assumptions. And when those narratives favour abstinence-only treatment, they can overshadow, dismiss, or distort evidence for other approaches.

The consequences are not theoretical. Smokers who hear conflicting or misleading information might delay or avoid switching to less harmful products. In the process, they remain susceptible to the well-established hazards of combustible tobacco — the No. 1 cause of preventable cancer globally.

In the end, the science on this matter isn’t unclear or partial. Smoking causes cancer due to combustion. Nicotine, though addictive, does not. Vaping is a reduced-risk product that has a significant potential to facilitate smoking cessation, as supported by toxicological, clinical, and real-world evidence.

The challenge, therefore, is not generating more data to validate a view but ensuring that the existing evidence is accurately communicated, responsibly interpreted, and translated into policy reform that places greater emphasis on harm reduction over ideology.

Measuring the Cancer Risk of Different Nicotine Products Via Biomarkers