June 9, 2026, 3:11 pm | Read time: 8 minutes
Many consider vaping a “gentle” alternative when quitting smoking. Initial indications from recent years are confirmed by the results of a population-based cohort study from South Korea. The study found the risk of lung cancer remains elevated after quitting smoking. This finding is particularly concerning for long-term smokers. FITBOOK examines the study, and editor Anna Echtermeyer reveals the method she used to successfully quit smoking 20 years ago.
What Vaping After Smoking Means for Lung Cancer Risk
Researchers at Seoul National University analyzed the health data of over 4.5 million former smokers from the South Korean National Health Screening Program to determine the long-term effects of switching to vaping after quitting tobacco. Compared to those who completely abstained from nicotine, switchers had a 1.56 times higher risk of developing lung cancer—and the risk of dying from cancer was even doubled. Following its classification as “probably carcinogenic” in March, the broad study published in “Nature Medicine” fundamentally shakes the image of e-cigarettes as a gentle alternative to smoking.1
4.5 Million Former Smokers Observed Over 6 Years
The scientists led by Yeon Wook Kim analyzed participants who had previously smoked conventional tobacco cigarettes. They divided them into different groups: smokers who completely quit (abstainers) and those who switched to e-cigarettes after quitting smoking. These subjects were observed over a period of up to six years (until December 2023) to record the incidence of new lung cancer cases and lung cancer-specific deaths.
The data comes from the National Health Screening Program and the database of the state health insurer in South Korea (NHIS). Since these programs regularly offer free preventive examinations, researchers have access to high-quality, consistent health data over the years.
Study Results: Vaping vs. Complete Nicotine Abstinence After Smoking
Overall, vaping after quitting tobacco led to a significantly higher risk of lung cancer and death than complete nicotine abstinence. Those who switched to e-cigarettes had a 56 percent higher risk of developing lung cancer during the observation period (about six years). The likelihood of dying from lung cancer during this time was doubled for switchers.
In addition to the lung cancer-specific risk, the general probability of dying within six years after switching to e-cigarettes (regardless of the cause of death) was also examined. As quoted from the original study by the “Ärzteblatt“, there was a significant increase of 22 percent compared to those who completely abstained from nicotine.2
Lung Cancer Risk Remains Elevated When Switching to Vaping
Thus, the actual health benefit of quitting is significantly diminished by vaping:
- Among people who completely abstained from cigarettes, the incidence of lung cancer decreased significantly by 44 percent.
- Among those who switched to e-cigarettes, there was only a measurable decrease of twelve percent. However, this value was not statistically significant, meaning a clear health advantage could not be definitively proven.
Effect of E-Cigarette Use Among Long-Term Smokers Over 50
The researchers also focused their analysis on individuals who, due to their history, carry the highest risk for lung cancer. These are people over 50 who had at least 20 pack-years before switching to e-cigarettes. This value is reached by smoking one pack a day for 20 years (or two packs a day for ten years).
In this group, the carcinogenic potential of e-cigarettes was most evident. Specifically, the likelihood of developing new lung cancer after switching to e-cigarettes was almost twice as high (plus 91 percent) compared to peers with similar histories who remained completely abstinent after quitting smoking. The likelihood of dying from lung cancer was also nearly doubled (plus 92 percent) among e-cigarette users in this group compared to those who were completely abstinent.
This means: People who have burdened their lungs with heavy smoking for decades benefit most from a total nicotine stop!
Contextualization in Existing Research and Limitations
It was already known that e-cigarettes are not harmless. In the past, DNA-damaging substances such as nitrosamines and toxic heavy metals (lead, nickel, chromium) have been detected in e-cigarette vapor.3 Previous analyses also showed an increased risk of strokes and heart attacks, especially with so-called “dual use” (simultaneous vaping and smoking).4 The current study now fills the crucial gap by showing that switching to e-cigarettes poses a broad risk for lung cancer compared to complete abstinence.
Despite 4.5 million participants whose data the current analysis considered, the specific case numbers among e-cigarette users—with 55 cases and 14 deaths—are still relatively low. Additionally, the study period of six years is actually too short for a disease like lung cancer, which often takes decades to develop, according to experts, for a final judgment.
Are the Results Applicable to Germany?
The results from South Korea cannot be directly applied to Germany. This is because much stricter regulations for the ingredients of liquids apply here.
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Researchers’ Conclusion
The scientists reach a clear, albeit cautiously worded conclusion: Although the study cannot provide direct causal evidence, the data suggests that using e-cigarettes after quitting smoking significantly weakens the enormous health benefits of complete abstinence. Instead of supporting the body’s recovery, the vapor seems to undermine protection against lung cancer.
For German experts, the results are an important signal. Reiner Hanewinkel from the Institute for Therapy and Health Research sees the “harm reduction” illusion “debunked” by the study. The idea that e-cigarettes are a harmless or even healthier alternative to tobacco smoking does not withstand the harsh statistical reality—especially the doubled risk of death, he told the “Ärzteblatt.” He emphasizes that the study’s demonstrated doubled risk for lung cancer-specific deaths (compared to true abstinence) proves that the supposedly “clean” vapor actually massively harms the body.
10 Tips to Quit Smoking
FITBOOK author Laura Pomer has previously described effective methods to ease the transition out of nicotine addiction:
- Start only when you are truly ready to take on the challenge. However, use spontaneous moments of disgust for the cigarette (such as when coughing or experiencing a foul smell) to quit immediately.
- Simply reducing the number of cigarettes usually doesn’t work, as you quickly fall back into old patterns. A decisive break is more effective.
- Focus on what you gain (better smell, taste, and condition) rather than seeing yourself as someone who has to give up something.
- Announce your decision to quit smoking to your circle of friends. This makes it harder to relapse, as you don’t want to embarrass yourself, and friends can be considerate.
- Replace typical smoking moments (such as coffee after a meal) with new habits. For example, applying hand cream or looking in the mirror, instead of reaching for sweets.
- Calculate how much money you save and plan a specific investment or reward with the saved amount.
- Exercise releases endorphins that can replace the nicotine kick and help “clear out” the lungs.
- A visit to the beautician can highlight how much smoking damages the skin (wrinkles, dull complexion) and motivate you to quit for a younger appearance.
- Support from apps can increase success through playful motivation, health trackers, and money counters.
- Actively confront yourself with the health risks (cancer, heart attack). Even a small number of cigarettes a day significantly increases the risk of lung cancer, which can reduce the desire to smoke.
I Was Successful with a Decisive Break 20 Years Ago
“In my early 20s, I quit smoking—overnight. At the time, I was going through about a pack a day. The trigger was a New Year’s resolution, but I wanted to give it more weight than the usual good intentions. Because I found smoking increasingly disgusting and expensive, I told as many people as possible about my plan to quit. Backtracking was not an option. On New Year’s Eve itself, I smoked until I felt sick. After that, it was over. It’s been 20 years since then, and I haven’t touched a single cigarette (or later an e-cigarette).
The first few weeks weren’t easy. Constant bad mood, irritability, the persistent feeling that something was missing. I avoided typical smoking moments to prevent relapse.
Back then, a pack of cigarettes cost around three euros. That’s why I started rolling my own. Recently, out of curiosity, I picked up a pack at the supermarket again. The price: nearly ten euros, I was almost shocked! Had I continued smoking as I did back then, the addiction would have cost me 55,000 euros by now. Whether I would have switched to e-cigarettes—I don’t know. I’m probably lucky that those seemingly harmless things didn’t exist back then.
My conclusion after more than 20 smoke-free years: You don’t need a perfect plan to quit. But determination helps. The radical break helped me—no exceptions, no ‘just one.’ Clearly: It was one of the best decisions of my life.”