Over one-third of cancers worldwide may be preventable, analysis shows

More than one in three cancer cases worldwide can potentially be prevented by reducing exposure to known and modifiable risk factors, according to a global analysis published in Nature Medicine.

Study findings

The study estimates that nearly 7.1 million among the 18.7 million cancer cases reported in 2022, or about 38%, of these were linked to factors that could have been reduced through public health interventions and lifestyle changes.

Researchers analysed data from 185 countries, covering 36 cancer types, to examine the influence of 30 preventable risk factors. These included tobacco use, alcohol consumption, infections, obesity, physical inactivity, air pollution, and occupational hazards.

Because cancers often develop years after exposure, the study mostly used risk-factor prevalence from around 2012, with a 10-year gap between exposure and diagnosis.

Risk factors, management

Smoking, identified as the single largest contributor, accounted for 15.1% of new cancer cases (around 33 lakh) worldwide. Infections were responsible for 10.2% of cases (around 23 lakh), while alcohol consumption contributed 3.2% (around 7 lakh).

These three major risk factors were associated with lung, stomach and cervical cancer, which accounted for nearly half of all preventable cases. (The authors also cautioned that many estimates are best read as approximates.)

The study also found notable differences between men and women. Nearly 45.4% of cancers among men were linked to preventable risks, compared with 29.7% among women.

Tobacco use continues to be the main contributor among men across most regions, with alcohol use and infections also playing a major role. Among women, the pattern varied depending on geography. In many low- and middle-income countries, infections such as human papillomavirus (HPV) and Helicobacter pylori were key drivers. In higher-income regions, smoking and high body mass index (BMI) were more significant contributors.

Regional variations were also identified. In East Asia, almost six in 10 cancers among men were linked to modifiable risks, largely driven by tobacco use and infections. In sub-Saharan Africa, infections accounted for nearly one-third of cancer cases among women, stressing gaps in vaccination coverage, sanitation and early screening.

Meanwhile, lifestyle-related risks such as smoking, obesity, physical inactivity and alcohol use were found to be prominent in parts of Europe and North America.

The findings emphasise that cancer risk factors are already well recognised and can be tackled through proven public health strategies like better tobacco control measures, vaccination against HPV and hepatitis B, better air quality, safer working conditions, healthier diets, and more physical activity.