medwireNews: Modifiable risk factors accounted for almost half of the global cancer mortality and disability-adjusted life–years (DALYs) in 2019, shows an analysis of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD).
“Given the increasing burden of cancer worldwide, this study can help policy makers and researchers identify important modifiable risk factors that could be targeted in efforts to reduce cancer burden globally, regionally, and nationally,” say the investigators in The Lancet.
They used the most recent iteration of the study – GBD 2019 – to estimate the contribution of 34 behavioral, environmental and occupational, and metabolic risk factors to mortality and ill health due to 23 different tumor types.
Overall, 4.45 million deaths and 105 million DALYs could be attributed to the risk factors included in the study, representing 44.4% of all cancer deaths and 42.0% of all cancer DALYs.
A larger proportion of deaths were attributable to risk factors among men than women, at 2.88 versus 1.58 million deaths, accounting for 50.6% and 36.3% of cancer deaths, respectively. And this was also the case for DALYs, at 67.5 versus 37.6 million, making up 48.0% and 34.3% of cancer DALYs.
The leading risk factor in both men and women was tobacco, responsible for a respective 36.3% and 12.3% of cancer deaths and 33.9% and 10.7% of cancer DALYs. The next most common risk factor in men was alcohol use (6.9% of deaths, 7.4% of DALYs) and in women was unsafe sex (6.5% and 8.2%, respectively).
The most common cause of risk-attributable deaths in men and women was tracheal, bronchus, and lung cancer, accounting for 42.2% and 27.2% of attributable cancer deaths, respectively, followed by colon and rectum cancer in men (13.3%) and cervical cancer in women (17.9%).
Christopher Murray (University of Washington, Seattle, USA) and fellow GBD 2019 Cancer Risk Factors Collaborators note that “[r]isk-attributable cancer burden varied by world region and Socio-demographic Index (SDI).”
For instance, just over a quarter (26.5%) of risk-attributable cancer deaths occurred in high SDI countries, even though these countries account for just 13.1% of the global population. The age-standardized death rates for risk-attributable cancers ranged from 60.8 and 62.3 per 100,000 person–years in high and high-middle SDI countries, respectively, to 33.9 per 100,000 person–years in low SDI countries.
The leading risk factors also differed by SDI – for example, smoking, alcohol use, and high BMI were the top three factors for death in high SDI countries, while smoking, unsafe sex, and alcohol use were the most common for low SDI countries.
The team also looked at changes over time, finding that from 2010 to 2019 risk-attributable cancer deaths rose globally by 20.4% and DALYs by 16.8%, with the greatest increases seen for metabolic risk-attributable deaths and DALYs, at 34.7% and 33.3%, respectively.
The authors of a related commentary describe the range of risk factors considered in the GBD study as “impressive,” but they highlight that “some important risk factors for cancer are not included, particularly infectious agents and ultraviolet exposure.”
Diana Sarfati and Jason Gurney, both from Te Aho o Te Kahu Cancer Control Agency in Wellington, New Zealand, also point out that “[a]ny study that draws together data from various global sources carries inherent methodological challenges,” such as the “substantial variability in availability and completeness of data across countries and regions.”
Nevertheless, “the overriding message of this research is clear: a substantial proportion of cancers, most likely a majority when infectious diseases are considered, is preventable,” write the commentators.
And they conclude: “The primary prevention of cancer through eradication or mitigation of modifiable risk factors is our best hope of reducing the future burden of cancer.”
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