Smoking, drinking, being overweight and other risk factors are to blame for almost half of all cancer deaths worldwide, according to the largest study of its kind, with 50% of male cancer deaths due to estimated risk factors and just more than a third for female deaths.
The region with the highest cancer death rates owing to risk factors was central Europe (82 deaths per 100 000 population).
Cancer is the second leading cause of death globally, and exposure to risk factors plays a key role in the biology and burden of many cancer types. Doctors do not know the exact causes of cancer, and not every case or death is avoidable, but there are risk factors that can increase people’s chance of developing it.
Now researchers at the University of Washington’s school of medicine have become the first to work out how risk factors contribute to cancer deaths globally, reports The Guardian.
Smoking, alcohol and a high body mass index (BMI) are the biggest contributors. In total, risk factors are responsible for nearly 4.45m cancer deaths a year, according to the findings published in The Lancet that used the Global Burden of Diseases, Injuries and Risk Factors (GBD) 2019 study.
That represents 44.4% of all cancer deaths worldwide. Half of all male cancer deaths in 2019 (50.6%, or 2.88m) were due to estimated risk factors, compared with more than a third of all female cancer deaths (36.3%, or 1.58m).
“This study shows the burden of cancer remains an important public health challenge growing in magnitude worldwide,” said Dr Christopher Murray, director of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington’s school of medicine and a co-senior author of the study.
“Smoking continues to be the leading risk factor for cancer globally, with other substantial contributors to cancer burden varying. Our findings can help policymakers and researchers identify key risk factors that could be targeted in efforts to reduce deaths and ill health from cancer regionally, nationally and globally.”
The leading risk factors globally for cancer deaths for both sexes were smoking, followed by alcohol use and high BMI. The biggest cause of risk-attributable cancer deaths for both women and men globally was tracheal, bronchus and lung cancer.
These account for 36.9% of all cancer deaths attributable to risk factors.
This was followed by cervical cancer (17.9%), colon and rectum cancer (15.8%) and breast cancer (11%) in women. In men, it was colon and rectum cancer (13.3%), oesophageal cancer (9.7%) and stomach cancer (6.6%).
The five regions with the highest cancer death rates owing to risk factors were central Europe (82 deaths per 100 000 population), east Asia (69.8 per 100 000), high-income North America (66 per 100 000), southern Latin America (64.2 per 100 000) and western Europe (63.8 per 100 000).
While not all cases or deaths are preventable, Cancer Research UK, the world’s largest independent cancer research organisation, says stopping smoking, reducing alcohol, maintaining a healthy weight, enjoying the sun safely and eating a balanced diet can all improve the odds.
Writing in a linked comment, Professor Diana Sarfati and Dr Jason Gurney of the University of Otago, New Zealand, who were not involved in the study, said preventing cancer by eradicating or reducing exposure to risk factors was “our best hope of reducing the future burden of cancer”.
“Reducing this burden will improve health and wellbeing, and alleviate the compounding effects on humans and the fiscal resourcing pressure within cancer services and the wider health sector,” they said.
Study details
The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019
GBD 2019 Cancer Risk Factors Collaborators *
Published in The Lancet on 20 August 2022
Summary
Background
Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally.
Methods
The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented.
Findings
Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]).
The Lancet linked comment – Preventing cancer, the only way forward (Open access)
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