Cancer remains the leading cause of illness and death worldwide, and cases are expected to rise in the coming decades if current trends continue. However, researchers estimate that about 40% of new cancer cases globally could be prevented. The conclusion comes from a large analysis examining 36 cancer types across nearly 185 countries.
The study identifies tobacco as the leading preventable cause, responsible for roughly 15% of all new cancer cases worldwide. Infections followed at 10%, with alcohol consumption accounting for 3%.
Earlier research published in 2022 estimated that about 7.1 million cancer diagnoses were linked to modifiable risk factors, as in exposures that can be changed or managed to reduce disease risk. Smoking remained the largest contributor, followed by infections and alcohol use.
Scientists at the World Health Organization (WHO) have similarly estimated that about 37% of cancer cases are linked to preventable causes such as infections, lifestyle choices, and environmental pollutants. These include cervical cancers caused by HPV infections, which vaccinations can help prevent, as well as multiple cancers linked to tobacco.
Although some cancers are unavoidable due to genetic mutations that accumulate with age or inherited risk, many stem from environment or behavioral factors. Smoking and ultraviolet radiation can directly damage DNA. Obesity and physical inactivity can alter hormone levels and inflammation, raising cancer risk, while air pollution may activate dormant cancer cells.
Researchers estimate that about 45% of cancers in men are preventable, compared with about 30% in women, partly because smoking rates tend to be higher among men. For men, smoking accounts for 23% of new cancer cases, followed by infections at 9% and alcohol at 4%. For women, infections account for 11%, smoking for 6%, and high body mass index for 3%.
Regional differences are also significant. In Europe, smoking is the leading preventable cause of cancer in women, followed by infection and obesity. In Sub-Saharan Africa, infections account for nearly 80% of preventable cancers in women, suggesting prevention efforts must be tailored to local conditions.
Among men, preventable cancer rates are highest in East Asia at 57% and lowest in Latin America and the Caribbean at 28%. For women, preventable cancers range from 24% in North Africa and West Asia to 38% in Sub-Saharan Africa.
Lung cancer linked to smoking and air pollution, stomach cancer tied to H pylori infection, and cervical cancer caused by HPV together account for nearly half of all preventable cancer cases worldwide.
Public health experts say the data shows that prevention is possible. Countries that have introduced strong tobacco policies or expanded HPV vaccination programs have already seen progress.
Key prevention strategies include quitting smoking, reduction in alcohol use, maintenance of a healthy weight, and protection against ultraviolet rays. Broader measures — such as tobacco regulation, vaccination against cancer-causing infections like HPV and hepatitis B, improved air quality, safer workplaces, healthier diets, and physical activity — could further reduce cancer rates.
Experts say coordinated action across sectors, from health and education to transport and labor policy, could prevent millions of cancer cases while also lowering long-term healthcare costs and improving population health.
If changes in lifestyle and environmental conditions are made, and prevention policies are effectively implemented, the heavy toll of cancer could be significantly reduced.
