One-third of cancers are preventable, says WHO

WHO says more than one-third of cancer cases are preventable. [Coutesy]

Cancer is among the top leading causes of death worldwide, accounting for nearly 10 million deaths in 2020, or nearly one in six deaths.  

The most common cancers are lung, breast, colon and rectum and prostate cancers. 

Nearly a quarter of deaths from cancer are due to tobacco use, alcohol consumption, high body mass index, low fruit and vegetable intake, and lack of physical activity. In addition, air pollution is an important risk factor for lung cancer. 

Cancer-causing infections, such as human papillomavirus (HPV) and hepatitis, are responsible for approximately 30 per cent of cancer cases in low- and lower-middle-income countries.

According to the World Health Organisation (WHO), many cancers can be cured if detected early and treated effectively.  

For many people, hearing the word cancer or being diagnosed with the disease can be heartbreaking. Some regard it as the end of life because of the fear and stigma surrounding the illness in society.

It is easy and natural to feel powerless against cancer, but research has suggested several ways people can reduce the risk of developing the disease.

According to a recent analysis by the WHO published in Nature Medicine, more than one-third of all cancer cases globally are preventable. Cervical, stomach and lung cancers account for nearly half of the cases considered preventable.

“This landmark study is a comprehensive assessment of preventable cancer worldwide, incorporating for the first time infectious causes of cancer alongside behavioural, environmental and occupational risks,” says Isabelle Soerjomataram, who is a medical epidemiologist at the World Health Organisation and a senior author of the research paper.

“Addressing these preventable causes represents one of the most powerful opportunities to reduce the global cancer burden,” she adds.

The analysis revealed that there were nearly 19 million new cancer cases in 2022. Approximately 38 per cent of those diagnoses were linked to 30 modifiable risk factors.

These risk factors included tobacco smoking, alcohol consumption, high body mass index, insufficient physical activity, smokeless tobacco, suboptimal breastfeeding, air pollution, ultraviolet radiation, infectious agents and more than a dozen occupational exposures.

Tobacco smoking topped the list of preventable risk factors associated with cancer, accounting for 15 per cent of all cancer cases recorded that year.

Among men, the risk was particularly high, with smoking contributing to 23 per cent of all new cancer cases globally in 2022.

Air pollution also plays a significant role, although its impact varies across regions. In East Asia, for instance, about 15 per cent of all lung cancer cases among women were linked to air pollution. 

In Northern Africa and Western Asia, meanwhile, approximately 20 per cent of lung cancer cases among men were attributed to air pollution.

Alcohol consumption ranked as the second leading preventable lifestyle risk factor. It accounted for 3.2 per cent of all new cancer cases, translating to approximately 700,000 diagnoses.

Researchers estimate that tobacco smoking and alcohol consumption together account for almost half of all preventable cancer cases.

Infections, meanwhile, were linked to roughly 10 per cent of new cancer diagnoses.

Among women, the largest share of preventable cancers was associated with high-risk human papillomavirus (HPV), which can lead to cervical cancer.

Fortunately, an HPV vaccine is now available and can help prevent many of these associated diseases, although coverage in many parts of the world remains low.

Stomach cancer cases are higher among men and are often associated with smoking, overcrowding, inadequate sanitation and poor access to clean water.

“This is the first global analysis to show how much cancer risk comes from causes we can prevent,” said Andre Ilbawi, WHO team leader for cancer control and co-author of the analysis.

“By examining patterns across countries and population groups, we can provide governments and individuals with more specific information to help prevent many cancer cases before they start.”

In summary, nearly four in 10 cancer cases worldwide in 2022 could have been prevented by eliminating exposure to the risk factors identified in the study.