Nearly 40% of cancer cases globally could be avoided, according to a new worldwide assessment by the World Health Organization (WHO) and its cancer research arm, the International Agency for Research on Cancer (IARC).
The analysis reviews 30 avoidable risk factors, such as tobacco use, alcohol consumption, obesity, lack of physical activity, air pollution, ultraviolet exposure, and—introduced for the first time—nine infections known to cause cancer.
The report was published ahead of World Cancer Day on 4 February, it estimates that preventable factors were responsible for 37% of all newly diagnosed cancer cases in 2022—approximately 7.1 million cases.
The findings emphasize the significant role prevention could play in reducing cancer rates worldwide.
Using data from 185 countries and covering 36 types of cancer, the study identifies tobacco as the single largest preventable cause, accounting for 15% of new cases globally. This is followed by infections at 10% and alcohol consumption at 3%.
Almost half of all preventable cancers worldwide were attributed to three types: lung, stomach, and cervical cancer. Lung cancer was mainly associated with smoking and air pollution, stomach cancer with Helicobacter pylori infection, and cervical cancer largely with human papillomavirus (HPV).
Dr André Ilbawi, WHO Team Lead for Cancer Control and a lead author of the study, said this is the first global assessment to quantify how much cancer risk comes from modifiable causes. He noted that analyzing trends across regions and population groups provides governments and individuals with actionable evidence to prevent many cancers before they develop.
Differences by sex and region
The study found a notably higher share of preventable cancers among men than women—45% of new cases in men compared with 30% in women. Among men, smoking was the dominant risk factor, responsible for 23% of new cases, followed by infections (9%) and alcohol use (4%). For women, infections were the leading preventable cause at 11%, followed by smoking (6%) and high body mass index (3%).
Dr Isabelle Soerjomataram, Deputy Head of the IARC Cancer Surveillance Unit and senior author of the report, described the study as the most comprehensive global evaluation of preventable cancer to date, highlighting the inclusion of infectious causes alongside behavioral, environmental, and occupational risks. She emphasized that tackling these factors offers a major opportunity to reduce the global cancer burden.
Preventable cancer rates varied considerably across regions. Among women, they ranged from 24% in North Africa and West Asia to 38% in sub-Saharan Africa. Among men, East Asia recorded the highest proportion at 57%, while Latin America and the Caribbean had the lowest at 28%. These variations reflect differences in risk exposure, socioeconomic conditions, prevention policies, and health system strength.
The report calls for tailored prevention strategies, including strong tobacco control, alcohol regulation, vaccination against cancer-causing infections such as HPV and hepatitis B, cleaner air, safer work environments, and healthier diets and physical activity levels.
It also stresses the importance of coordinated action across multiple sectors—including health, education, energy, transport, and labour—to reduce cancer risk. Addressing preventable causes can not only lower cancer incidence but also reduce long-term healthcare costs and improve overall population health and well-being.