Research suggests genetics can influence cancer risk among smokers, but experts say no level of tobacco use is safe
Many people who smoke for years never develop lung cancer, while others develop cancer after smoking far less. Scientists say the answer lies partly in genetics, DNA repair mechanisms and how individual bodies respond to tobacco-related damage. However, medical experts stress that smoking remains one of the leading causes of preventable disease and death worldwide, regardless of a person's genetic makeup.
NewsFlash Daily: Cigarette packets carry health warnings stating that smoking causes cancer, heart disease and other serious illnesses. Yet, questions continue to arise about why some long-term smokers never develop cancer while others are diagnosed despite smoking comparatively less.
Recent scientific research suggests that inherited genetic differences may partly explain these variations. However, researchers and health experts emphasise that these findings do not mean smoking is safe or that some people are immune to its harmful effects.
Cambridge Study Finds Genetics May Influence Cancer Risk
Researchers at the University of Cambridge recently examined nearly 600 tumours from laboratory mice with different genetic backgrounds.
The study found that although tumours developed in all groups of mice, the DNA mutations within those tumours differed depending on the animals' genetic makeup.
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The findings suggest that two people exposed to similar amounts of tobacco smoke may experience different levels of DNA damage because of inherited biological differences.
Researchers caution that the study was conducted in mice, and additional research involving humans is needed before drawing definitive conclusions.
The research suggests genetics may influence how tobacco damages DNA, but it does not indicate that smoking is safe for anyone.
Why Smoking Causes Cancer in Some People Earlier Than Others
According to scientists, tobacco smoke contains thousands of chemicals, many of which are known carcinogens capable of damaging DNA.
Every smoker is exposed to these harmful substances, but the body's ability to repair DNA damage varies from person to person.
Individuals with stronger DNA repair mechanisms or certain protective genetic variants may accumulate mutations more slowly, while others may develop cancer after comparatively lower tobacco exposure.
However, genetics is only one of several factors influencing cancer risk. Age, duration of smoking, environmental exposure, lifestyle and overall health also play important roles.
Long-Lived Smokers Are Rare Exceptions
Stories occasionally emerge about individuals who smoked for decades and lived beyond 100 years.
One widely reported case involved Jan Steenberg, a South African man who reportedly claimed to be 121 years old and said he had smoked for more than a century. His reported age, however, has not been independently verified by international longevity organisations.
Verified historical records include Jeanne Calment, the oldest verified person in recorded history, who smoked from early adulthood until the age of 117. Another verified supercentenarian, Christian Mortensen, was also known to smoke cigars during much of his life.
Scientists describe such individuals as statistical outliers whose exceptional longevity should not be viewed as evidence that smoking is harmless.
Researchers say rare cases of smokers living beyond 110 years do not change the overwhelming scientific evidence linking tobacco to disease and premature death.
Indian Example Highlights Importance of Healthy Lifestyle
In India, Swami Sivananda became widely known for his exceptional longevity. Unlike long-lived smokers, Swami Sivananda attributed his health to lifelong abstinence from tobacco and alcohol, a simple diet, regular yoga practice and disciplined daily habits.
His example illustrates that exceptional longevity can occur under very different lifestyles and should not be used to draw conclusions about the effects of smoking.
Smoking Increases Risk Beyond Lung Cancer
Medical experts note that tobacco affects far more than the lungs.
Smoking significantly increases the risk of:
- Lung cancer
- Chronic Obstructive Pulmonary Disease (COPD)
- Heart disease
- Stroke
- Cancers of the mouth, throat, oesophagus, bladder, pancreas and several other organs
The World Health Organization identifies tobacco use as one of the leading preventable causes of death globally.
Researchers emphasise that while genetics may influence how much risk an individual faces, it cannot eliminate the harmful effects of tobacco.
Lungs Begin Recovering After Smoking Stops
Scientists say one of the body's most important defence mechanisms is the lungs' ability to regenerate.
Studies indicate that after a person quits smoking, healthy lung cells that have escaped tobacco-related mutations begin multiplying and gradually replace damaged cells.
This process improves lung health over time and may reduce the future risk of smoking-related diseases, although the extent of recovery depends on factors such as age, smoking history and existing damage.
Researchers say the body's DNA repair systems also become more effective once exposure to tobacco smoke ends.
No Cigarette Is Safe, Experts Say
Researchers stress that genetic differences should not be interpreted as protection against smoking.
While genetics may help explain why individuals develop diseases at different rates, every cigarette exposes the body to harmful chemicals that increase the likelihood of serious illness.
Health experts continue to recommend quitting smoking as the most effective way to reduce the risk of cancer, cardiovascular disease and chronic respiratory illness.
Scientists emphasise that there is no such thing as a safe cigarette, and quitting tobacco remains the single most effective step to improve long-term health.
