As the world marked World Cancer Day, the World Health Organization (WHO) has warned that tobacco smoking remains the biggest cause of cancer worldwide, driving millions of cases that could be avoided.
A new global study by WHO and its cancer research agency, the International Agency for Research on Cancer (IARC), shows that about 7.1 million cancer cases in 2022 were linked to preventable causes.
Smoking alone was responsible for 15% of all new cancers globally, making it the single largest cancer risk, while alcohol consumption accounted for a further 3%.
“Tobacco is still the biggest cancer killer,” said Dr André Ilbawi, WHO’s Team Lead for Cancer Control. “If we reduce smoking and harmful drinking, we can prevent a huge number of cancer cases before they start.”
Lung cancer leads
The report found that nearly half of all preventable cancers came from just three types — lung, stomach and cervical cancer.
Lung cancer, which is mainly caused by smoking and air pollution, was the largest contributor.
WHO says tobacco and alcohol damage many parts of the body and increase the risk of lung, throat, mouth, liver, breast, stomach and bladder cancers, making them among the most dangerous cancer risks worldwide.
Other major preventable causes
Besides tobacco and alcohol, the WHO report identified several other causes of cancer that can be prevented.
These include cancer-causing infections such as HPV, hepatitis B and Helicobacter pylori, which together account for about 10 percent of global cancer cases, high body mass index (overweight and obesity), physical inactivity, air pollution, ultraviolet radiation from the sun, and exposure to harmful chemicals and hazards in workplaces.
The study, which examined 30 different preventable risk factors across 36 cancer types in 185 countries, found that stomach cancer was largely linked to Helicobacter pylori infection, while cervical cancer was overwhelmingly caused by human papillomavirus (HPV), which can be prevented through vaccination.
Men hit hardest
The study shows that men carry the biggest burden of preventable cancers.
Overall, 45% of new cancer cases in men were linked to preventable causes, compared to 30% in women.
Among men, smoking alone accounted for about 23% of all new cancer cases, followed by infections at 9%and alcohol at 4%.
Among women globally, infections accounted for 11% of new cancer cases, followed by smoking at 6 percent and high body mass index at 3 percent.
Regional differences
The report also found major differences across regions.
Among women, the share of preventable cancers ranged from 24% in North Africa and West Asia to 38% in sub-Saharan Africa.
Among men, the highest burden was recorded in East Asia at 57 percent, while the lowest was in Latin America and the Caribbean at 28 percent.
A call to act
WHO is urging governments to raise tobacco and alcohol taxes, enforce smoking bans, restrict advertising, and help users quit, while also expanding vaccination against HPV and hepatitis B, improving air quality, promoting healthier diets and physical activity, strengthening workplace safety, and improving access to clean energy and safer transport.
“Addressing these preventable causes represents one of the most powerful opportunities to reduce the global cancer burden,” said Dr Isabelle Soerjomataram of IARC.