Four in 10 cancers worldwide could be prevented, WHO warns

A global study by the World Health Organisation (WHO) and its cancer research arm, the International Agency for Research on Cancer (IARC), has revealed that nearly four in 10 cancer cases worldwide could be avoided through preventive measures.

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Published on the WHO website on 3 February ahead of World Cancer Day, the analysis estimated that 37 per cent of all new cancer cases recorded in 2022, around 7.1 million cases, were linked to preventable causes.

Key risk factors identified

The study examined 30 modifiable risk factors, including tobacco use, alcohol consumption, high body mass index, physical inactivity, air pollution, ultraviolet radiation, and, for the first time, nine cancer-causing infections.

Drawing on data from 185 countries and 36 cancer types, researchers found tobacco to be the single largest preventable cause of cancer worldwide.

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Smoking alone accounted for 15 per cent of all new cases, followed by infections at 10 per cent and alcohol consumption at three per cent.

Three cancer types, lung, stomach, and cervical cancer, were responsible for nearly half of all preventable cases globally among men and women.

Lung cancer was linked primarily to smoking and air pollution, stomach cancer to Helicobacter pylori infection, and cervical cancer almost entirely to the human papillomavirus (HPV).

André Ilbawi, WHO team lead for cancer control and author of the study, noted that this is the first global analysis to show how much cancer risk comes from causes we can prevent.

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

Implications for Nigeria

The findings are particularly relevant for Nigeria, where cancer is a growing public health challenge.

According to IARC’s GLOBOCAN 2022 data, the country recorded about 127,700 new cancer cases and nearly 80,000 deaths in 2022.

Over 269,000 Nigerians are estimated to be living with a cancer diagnosis within the last five years.

The report revealed that the cancer burden in Nigeria is higher among women, largely due to breast and cervical cancers, while prostate cancer is among the most common in men.

Many of these cancers are linked to preventable factors such as infections, tobacco use, alcohol consumption, and late detection.

Health experts have warned that late diagnosis, limited screening coverage, and gaps in access to treatment contribute to high mortality, making prevention a critical intervention.

Higher burden among men

Globally, the WHO study found that preventable cancers were more common in men, with about 45 per cent of new cases linked to preventable causes, compared with 30 per cent in women.

Among men, smoking accounted for 23 per cent of new cases, infections for nine per cent, and alcohol consumption for four per cent.

For women, infections were the leading preventable cause at 11 per cent, followed by smoking at six per cent and high body mass index at three per cent.

Regional disparities

The report highlighted wide regional differences in preventable cancer burden.

Among women, preventable cancers ranged from 24 per cent in North Africa and West Asia to 38 per cent in sub-Saharan Africa, where infection-related cancers such as cervical cancer remain common.

For men, East Asia recorded the highest burden at 57 per cent, while Latin America and the Caribbean recorded the lowest at 28 per cent.

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These disparities reflect variations in exposure to behavioural, environmental, occupational, and infectious risks, as well as differences in socioeconomic development, national prevention policies, and health system capacity.

Stronger prevention measures

Describing the findings as a landmark assessment, Isabelle Soerjomataram, deputy head of IARC’s cancer surveillance unit and senior author of the study, said tackling preventable causes represents a major opportunity to reduce the global cancer burden.

“This landmark study is a comprehensive assessment of preventable cancer worldwide, incorporating infectious causes alongside behavioural, environmental, and occupational risks,” she said.

The study recommended stronger tobacco control and alcohol regulation, expanded vaccination against cancer-causing infections such as HPV and hepatitis B, improved air quality, safer workplaces, and healthier food and physical activity environments.

It also called for coordinated action across sectors, including health, education, energy, transport, and labour, to prevent millions of families from facing cancer, reduce long-term healthcare costs, and improve population health.

World Cancer Day

World Cancer Day, observed annually on 4 February, aims to raise awareness of the disease, encourage early detection and treatment, and reduce stigma and misinformation, with the 2026 theme, United by Unique.