The Global Burden of Cancer Attributable to Risk Factors, 2010–19: A Systematic Analysis for the Global Burden of Disease Study 2019
Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. This study analyzed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally.
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.
Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million deaths and 105 million DALYs for both sexes combined, representing 44.4% of all cancer deaths and 42.0% of all DALYs.
There were 2.88 million risk-attributable cancer deaths in males and 1.58 million risk-attributable cancer deaths in females.
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% and DALYs by 16.8%, with the greatest percentage increase in metabolic risks.
The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019.
Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden.
Detailed results regarding alcohol and cancer
Alcohol and cancer DALYs globally
The leading Level 2 risk factor in males in terms of attributable cancer DALYs was tobacco, which accounted for 33.9% of all cancer DALYs in males in 2019.
Alcohol use, dietary risks, and air pollution were the next greatest risk factors, accounting for 7.4%, 5.9%, and 4.4%, respectively, of all male cancer DALYs in 2019.
Tobacco was also the leading Level 2 risk factor for females globally in terms of attributable cancer DALYs and accounted for 10.7% of all female cancer DALYs in 2019. Unsafe sex was the second leading risk factor for females, accounting for 8.2% of all female cancer DALYs in 2019, followed by dietary risks (5.1%), high BMI (4.7%), and high fasting plasma glucose (3.6%).
The disparities in cancer DALYs attributable to behavioural risk factors, such as smoking (33.2% for males vs 8.9% for females) and alcohol use (7.4% for males vs 2.3% for females), which might be driven by higher exposure to these behavioural risk factors among males than females.
Ranking of Level 2 risk factors by attributable cancer deaths globally in 2019 showed similar ranking as by attributable cancer DALYs.
Risk factors for age-standardized cance DALYs and SDI
Different patterns in the leading risk factors for attributable cancer age-standardised DALY rates were observed globally and across the SDI spectrum.
The leading nine risk factors at the most detailed level contributing to global cancer burden defined by age-standardised DALY rates did not change between 2010 and 2019, and the top three risk factors (smoking, alcohol use, and high BMI) were the same in the high SDI quintile as globally.
Smoking and alcohol use remained the top two leading risk factors in the middle SDI quintile in 2010 and 2019, with unsafe sex decreasing from third to fifth position, high BMI rising from fourth to third position, and ambient particulate matter pollution rising from fifth to fourth position.
In the low SDI quintile, smoking remained the leading risk factor for risk-attributable cancer burden, with unsafe sex ranked second and alcohol use third in both 2010 and 2019. Within the top five leading risk factors in the low SDI quintile, high BMI and high fasting plasma glucose both increased (fifth to fourth, and sixth to fifth, respectively), and household air pollution from solid fuels decreased (fourth to sixth) between 2010 and 2019.
Alcohol use is a top-three risk factor for cancer across all three socio-demographic Index (SDI) levels as well as for age-standardised DALY rates.
When compared with a previous effort to quantify the fatal burden of cancer attributable to risk factors globally, this study found a greater percentage of cancer deaths attributable to risk factors when estimating more risk factors (44.4% in 2001 in GBD 2019 compared with 35% in 2001 in the previous study), although both studies found leading contributions by smoking and alcohol use globally and unsafe sex in lower-income settings.
Most attributable cancer DALYs were accounted for by behavioural risk factors, such as tobacco use, alcohol use, unsafe sex, and dietary risks, suggesting a need for concerted efforts to address behavioural risk factors to effectively reduce cancer burden globally.
Attributable cancer DALYs from each Level 1 risk factor group generally increased with increasing SDI, and although there were similarities in the leading risk factors across the SDI spectrum for both sexes combined (ie, smoking and alcohol use), there were differences in risk factor patterns following these leading risks, highlighting the need for cancer risk reduction efforts to be context specific.
Between 2010 and 2019, age-standardised cancer DALYs attributable to all risk factors declined by 7.8%. Despite this decline, a global increase in age-standardised cancer DALYs (3.8%) attributable to metabolic risks was seen, largely driven by substantial increases in low and low-middle SDI countries.
Total risk-attributable cancer absolute DALY burden globally and in all SDI quintiles grew between 2010 and 2019, underscoring an expanding need for health systems around the world with capacity to comprehensively care for individuals with cancer, while developing and implementing cancer control efforts that consider risk reduction strategies. These estimates might help inform cancer control planning by identifying leading modifiable risk factors for cancer around the world, including for countries that might not have previous local research on cancer burden and cancer risk factor exposures.
Prevention through alcohol policy
Globally, there has been substantial progress in reducing exposure to tobacco that can be linked to coordinated international and national prevention efforts.
Interventions through taxation and regulatory policies for tobacco smoking, including smoke-free policies, increased tobacco taxes, and advertisement bans guided by the WHO Framework Convention on Tobacco Control, have played a major role in these efforts.
Similar efforts, including taxation and advertisement bans, have been recommended to help reduce exposure to alcohol.
Behavioural risk factors are strongly influenced by the environment in which people live and individuals with cancer should not be blamed for their disease.