A significant share of cancer cases diagnosed worldwide may never have occurred if proven prevention measures had been widely adopted, according to new findings released by the World Health Organisation (WHO) and its cancer research agency.
The analysis, published ahead of World Cancer Day, indicates that more than one-third of all new cancer diagnoses recorded globally in 2022 were linked to causes that can be reduced or eliminated. In real terms, this translates to over seven million preventable cases in a single year.
Researchers assessed exposure to 30 risk factors that are within human control, ranging from lifestyle choices such as tobacco and alcohol use to environmental hazards like polluted air and ultraviolet radiation. For the first time, the study also factored in nine infections known to trigger cancer.
Using data drawn from 185 countries and 36 cancer types, the researchers identified tobacco use as the most damaging factor, responsible for the largest proportion of avoidable cases. Cancer-causing infections followed closely, while alcohol consumption ranked third.
Globally, lung, stomach and cervical cancers accounted for almost half of all cancers linked to preventable causes. Smoking and air pollution were found to drive lung cancer rates, stomach cancer was largely associated with Helicobacter pylori infection, and cervical cancer was overwhelmingly linked to the human papillomavirus (HPV).
According to André Ilbawi, WHO’s lead for cancer control and one of the study’s authors, this is the first time a global assessment has clearly quantified how much cancer risk is tied to factors people and governments can address. He said the findings provide a practical roadmap for prevention, especially in countries where health systems are under pressure.
What the findings mean for Nigeria
The report carries serious implications for Nigeria, where cancer cases continue to rise. Data from the International Agency for Research on Cancer (IARC) shows that more than 127,000 Nigerians were newly diagnosed with cancer in 2022, while close to 80,000 people died from the disease within the same period.
Breast and cervical cancers remain the most common among women, while prostate cancer dominates among men. Many of these cases are linked to preventable risks such as infections, tobacco use, alcohol intake, and delayed diagnosis.
Health experts say weak screening programmes, late presentation, and uneven access to treatment continue to fuel high mortality rates, making prevention one of the most cost-effective tools available to the country. More Nigeria-focused public health updates can be found on AfriGlobal News – Health.
Men face higher preventable cancer risk
On a global scale, the study found that men bear a heavier burden of preventable cancers than women. About 45 per cent of cancer cases among men were linked to avoidable causes, compared with roughly 30 per cent among women.
Smoking was the dominant driver among men, while infections were the leading preventable cause among women, followed by smoking and obesity-related factors.
The burden also varied widely across regions. Sub-Saharan Africa recorded some of the highest proportions of infection-related cancers, particularly among women, while East Asia had the highest share of preventable cancers among men. These differences reflect uneven exposure to risk factors, as well as disparities in health systems, economic development, and public policy.
Isabelle Soerjomataram, a senior researcher at IARC, described the findings as a major opportunity for governments to reduce cancer deaths. She said strong action on tobacco control, alcohol regulation, vaccination against HPV and hepatitis B, cleaner air, safer workplaces, and healthier diets could prevent millions of cases worldwide.
World Cancer Day is marked every year on 4 February to promote awareness, early diagnosis, and equitable access to care. More details on the study and global cancer prevention efforts are available on the World Health Organisation website.
