According to new analysis, a large proportion of the burden could be prevented through lifestyle change.
Almost half of cancer deaths are caused by preventable risk factors, primarily tobacco, high BMI and alcohol, and that percentage is increasing, according to a new analysis of global figures.
The study, published in The Lancet, analysed a comprehensive list of 82 cancer risk-outcome pairs (23 cancers, 34 risk factors), their impact on the cancer burden nationally and globally, and trends from 2010 to 2019 using figures from the 2019 Global Burden of Diseases, Injuries, and Risk Factors Study, finding that the number attributable to modifiable risk factors went up.
“Reducing exposure to these modifiable risk factors would decrease cancer mortality and disability-adjusted life-years rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden,” the authors said.
Researchers found that modifiable risk factors – either environmental and occupational, behavioural or metabolic – resulted in an estimated 4.5 million deaths and 105 million disability-adjusted life-years. That’s just over 44% of all cancer deaths and 42% of all disability-adjusted life-years.
This was an increase of around 20% from 2010. One in three deaths due to avoidable risks were from tracheal, bronchus and lung cancer. The next most common cancers in men were colon and rectum, oesophageal and stomach cancer. In women they were cervical, colon and rectum, and breast cancer.
The leading risk factors were behavioural, but the largest growing modifiable risks were metabolic, especially in low and low to middle-income countries.
Smoking, alcohol use and obesity were the biggest risk factors globally, in that order. But in low socio-economic regions they were smoking, unsafe sex and alcohol.
There was quite a difference in cancer figures depending on socio-demographic index. In high income countries, cancer deaths linked to modifiable factors accounted for 26% of global cancer deaths. In low to middle index countries, it was 74%.
Central Europe had by far the largest number of modifiable risk attributable age standardised cancer death rates in the world (82 per 100,000 person years). The other areas in the top five were East Asia, well-off parts of North America, southern Latin America, and Western Europe.
In Australia, risk-attributable cancer deaths accounted for around 40% of all cancer deaths and disability-adjusted life years. One in five of those deaths was attributed to smoking.
Deaths due to avoidable risk factors made up half of all cancer deaths in men and 36% of cancer deaths in women.
There were significant differences between some male and female risk factors. For instance, smoking was related to around one in three male cancer deaths, but fewer than one in 10 female cancer deaths.
Alcohol accounted for around 2% of cancer deaths in females, and around 7% in males. Men were more than three times as likely as women to die from exposure to carcinogens at work (around 3.9% vs 1.3%). Meanwhile, disability adjusted life years were increasing at a faster rate for women than for men.
“This result might suggest inequities in our approach to cancer prevention by sex and a need for future sex-specific assessments of effective cancer risk factor interventions,” the authors noted.
The authors said their findings showed there was a need for population-level context-specific strategies and investment to reduce exposure to risk factors, control cancer where it was unavoidable, and provide care to those living with the disease.
