Up to seven million cancer cases each year could be prevented, according to the first comprehensive global assessment of avoidable cancer risks, conducted by scientists from the World Health Organization.
The analysis estimates that 37 percent of cancers worldwide are caused by factors that can, in principle, be avoided. These include infections, lifestyle choices, and environmental exposures such as tobacco smoke and air pollution.
The findings highlight what researchers describe as a significant opportunity to reduce the global cancer burden through targeted prevention policies, vaccination programmes and environmental regulation.
What makes cancers preventable
The study was carried out by the International Agency for Research on Cancer, which analysed cancer incidence data from 185 countries, linking cases recorded in 2022 to exposure to known risk factors a decade earlier.
In total, researchers examined 30 established cancer risk factors, ranging from behavioural and environmental exposures to infectious agents.
Some of these factors directly damage DNA, such as smoking tobacco or exposure to ultraviolet radiation. Others act indirectly by altering hormones, inflammation or immune responses, including obesity, physical inactivity and air pollution.
The study also assessed nine cancer-causing infections, including:
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Human papillomavirus (HPV), linked to cervical cancer
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Hepatitis viruses, associated with liver cancer
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Helicobacter pylori, a bacterium linked to stomach cancer
The biggest contributors
Out of more than 18 million cancer cases worldwide, the analysis identified three dominant preventable causes:
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Tobacco use, responsible for approximately 3.3 million cases
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Cancer-causing infections, accounting for 2.3 million cases
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Alcohol consumption, linked to around 700,000 cases
Lung, stomach and cervical cancers together made up nearly half of all preventable cancer cases, reflecting the combined impact of smoking, infections and environmental exposures.
Unequal risks across regions and sexes
The data reveal marked differences in cancer risk patterns across regions and between men and women.
Globally, 45 percent of cancers in men were deemed preventable, compared with 30 percent in women, a gap largely attributed to higher smoking rates among men.
Regional differences were even more pronounced:
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In Europe, smoking is the leading preventable cause of cancer in women, followed by infections and obesity.
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In sub-Saharan Africa, infections account for almost 80 percent of preventable cancers in women, underscoring the importance of vaccination and infection control.
Researchers stress that prevention strategies must therefore be region-specific, reflecting local risk profiles rather than applying a single global model.
Prevention as policy
Researchers involved in the study emphasised that these figures are not theoretical.
Countries that have implemented strong tobacco control measures or nationwide HPV vaccination programmes have already demonstrated that cancer prevention policies can significantly reduce incidence over time.
The study, published in the medical journal Nature Medicine, frames prevention as one of the most effective tools available to public health systems.
As WHO officials note, while not all cancers can be prevented, the proportion that can be reduced through policy choices, regulation and public health investment is substantial and, crucially, within reach.
Source: BBC