Up to seven million cancer cases worldwide could be prevented every year, according to the first-ever global analysis by scientists at the World Health Organization (WHO).
The report estimates that about 37 per cent of all cancers are caused by infections, lifestyle habits and environmental pollution — factors that can largely be avoided. These include cervical cancer linked to the human papillomavirus (HPV), which can be prevented through vaccination, as well as several cancers caused by tobacco smoke.
Researchers say the findings show a “powerful opportunity” to save lives if countries invest in prevention. While some cancers are unavoidable — due to ageing or inherited genes — nearly four in every 10 cases could be prevented.
Dr Isabelle Soerjomataram of the International Agency for Research on Cancer (IARC) said many people are often surprised by how high the figure is, describing it as “a substantial number”.
The IARC, a specialised cancer agency of the WHO, analysed 30 known preventable cancer risk factors. These include smoking and excessive exposure to ultraviolet (UV) radiation, which directly damage DNA; obesity and physical inactivity, which affect hormones and inflammation; and air pollution, which can trigger cancer cells. The study also examined nine cancer-causing infections, including HPV, hepatitis viruses linked to liver cancer, and Helicobacter pylori, which causes stomach cancer.
Using cancer data from 2022 and exposure to risk factors a decade earlier across 185 countries, researchers identified the three biggest contributors to the world’s more than 18 million cancer cases:
- Tobacco smoking – 3.3 million cases
- Infections – 2.3 million cases
- Alcohol use – 700,000 cases
However, cancer risks vary significantly by region and gender. Globally, 45 per cent of cancers in men are preventable, compared with 30 per cent in women, largely due to higher smoking rates among men.
In Europe, smoking is the leading preventable cause of cancer among women, followed by infections and obesity. In sub-Saharan Africa — including Ghana — infections are by far the biggest risk, accounting for nearly 80 per cent of preventable cancers in women.
This highlights the need for country-specific solutions, such as stronger vaccination programmes, better sanitation, and public education on healthy lifestyles.
“This landmark study brings together infectious, behavioural, environmental and occupational causes of cancer for the first time,” Dr Soerjomataram said. “Addressing these preventable factors offers one of the strongest opportunities to reduce the global cancer burden.”
Published in Nature Medicine, the report found that lung cancer (linked to smoking and air pollution), stomach cancer (linked to H. pylori infection), and cervical cancer (linked to HPV) account for nearly half of all preventable cancer cases worldwide.
Dr Andre Ilbawi, WHO’s team lead for cancer control, described the findings as “good news”, noting that many countries have already reduced cancer rates through anti-smoking laws and HPV vaccination.
“Our aim is to push preventable cancers as close to zero as possible,” he said.
