Up to four in 10 cancer cases worldwide are preventable as they are caused by issues such as smoking, excess weight or exposure to the sun or sunbeds, analysis shows.
Experts said it was “good news” that many cancer cases could be avoided and called for prevention strategies to focus on tackling risks and not blame.
For the study, experts from the World Health Organisation (WHO) and its International Agency for Research on Cancer (IARC) looked at 30 risk factors that cause the disease, including smoking, drinking alcohol, high body mass index, air pollution and infections.
Using data from across 185 countries and 36 cancer types they estimate that about 7.1 million (37 per cent) of the 18.7 million new cancer cases diagnosed globally in 2022 were preventable. The WHO said the findings, released before World Cancer Day is marked on February 4, highlighted the enormous potential of prevention in reduce the global cancer burden.
Tobacco was identified as the top preventable cause, responsible for 15 per cent of all new cancer cases, followed by infections (10 per cent) and alcohol consumption (3 per cent).
Three cancer types – lung, stomach and cervical cancer – accounted for nearly half of all preventable cancer cases in men and women.
Lung cancer was primarily linked to smoking and air pollution, stomach cancer was largely attributable to Helicobacter pylori infection, and cervical cancer was overwhelmingly caused by human papillomavirus (HPV).
“A cancer diagnosis is life changing, yet experiences differ sharply between and within countries," said Dr Andre Ilbawi, WHO team lead for cancer control. “For a privileged few, access and innovation are driving survival rates beyond 70 per cent but for far too many, cancer remains a death sentence, often compounded by devastating social and financial hardships.
“Today, we are here to celebrate good news founded on strong science. Many cancers are preventable.”
Dr Ilbawi said the findings, published in the journal Nature Medicine, will help scientists to "understand what is driving the cancer burden and what are the highest risks for different populations”.
“Tobacco, alcohol, air pollution, unhealthy diets, physical activity and infections such as human papillomavirus and hepatitis – these continue to drive avoidable injury to the avoidable illness and death,” he added.
“These are the same risk factors that place a massive strain on communities’ systems through many other diseases beyond cancer. Investing in cancer prevention, therefore, delivers wide-ranging health, societal and economic benefits.
“There’s one key message to recall; prevention must be communicated carefully, focusing on risk reduction, not blame, emphasising policy and structural solutions, acknowledging uncertainty and respecting the dignity of people living with cancer.”
The risk of suffering a preventable cancer also varied by sex. According to the study, 45 per cent of new global cancer cases among men were linked to preventable risk factors compared with 30 per cent among women.
In men, smoking accounted for an estimated 23 per cent of all new cases, followed by infections at 9 per cent and alcohol at 4 per cent. Among women globally, infections accounted for 11 per cent of all new cases, followed by smoking at 6 per cent and high body mass index at 3 per cent.
Dr Isabelle Soerjomataram, deputy head of the IARC cancer surveillance unit and senior author of the study, said: “Addressing these preventable causes represents one of the most powerful opportunities to reduce the global cancer burden.
“Breaking this down to major risk factors, smoking accounts for 3.3 million cases, infections for 2.2 million cases, and alcohol contributes for approximately 700,000 cases. So these three factors represent the majority of preventable global cancer burden, highlighting where prevention efforts could have the greatest impact.
“Breaking this down to major risk factors, smoking accounts for 3.3 million cases, infections for 2.2 million cases, and alcohol contributes for approximately 700,000 cases. So these three factors represent the majority of preventable global cancer burden, highlighting where prevention efforts could have the greatest impact.”
Among women, preventable cancers ranged from 24 per cent in North Africa and West Asia to 38 per cent in sub-Saharan Africa. Among men, the highest burden was observed in East Asia at 57 per cent, with the lowest in Latin America and the Caribbean at 28 per cent. These differences reflect varying exposure to behavioural, environmental, occupational and infectious risk factors, as well as differences in socioeconomic development, national prevention policies and health system capacity.
