New Delhi: Smoking, alcohol consumption and a high body mass index (BMI) are the leading risk factors associated with cancer-related deaths, according to a study published in The Lancet Friday with contributions by researchers from around the globe.
The researchers arrived at this conclusion after analysing data from the 2019 Global Burden of Diseases, Injuries, and Risk Factors (GBD) study in order to assess the role of 34 risk factors in death and ill health associated with 23 cancer types. The risk factors they analysed accounted for 4.45 million or 44.4 per cent of cancer deaths around the world in 2019.
The researchers measured the risks in terms of DALY or disability-adjusted life years — an international metric for measuring the burden of disease. The World Health Organization (WHO) describes one DALY as “the loss of the equivalent of one year of full health”.
According to the WHO, “DALYs for a disease or health condition are the sum of the years of life lost due to premature mortality (YLLs) and the years lived with a disability (YLDs) due to prevalent cases of the disease or health condition in a population.”
The study said: “The leading Level 2 risk factor in males in terms of attributable cancer DALYs was tobacco, which accounted for 33.9 per cent of all cancer DALYs in males in 2019.”
According to the GBD’s four-tier classification of risks, Level 1 includes aggregates of environmental, occupational, behavioural, and metabolic risks, while Level 2 comprises 20 risk categories including air pollution, child and maternal malnutrition, and high BMI. Level 3 includes particulate matter pollution and child growth failure, and Level 4 includes risks posed by household air pollution from solid fuels and child stunting, among others.
Tobacco was also the leading “Level 2 risk factor” among women across the globe in terms of attributable cancer DALYs, and accounted for “10.7 per cent of all female cancer DALYs in 2019”, the study said.
It went further to add that after tobacco, “alcohol use, dietary risks, and air pollution were the next greatest risk factors, accounting for 7.4 per cent, 5.9 per cent, and 4.4 per cent , respectively, of all male cancer DALYs in 2019”.
In the case of women, researchers identified unsafe sex as the second leading risk factor, adding that it accounted for 8.2 per cent of all female cancer DALYs in 2019, “followed by dietary risks, high BMI, and high fasting plasma glucose”.
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, said the findings illustrate that the “burden of cancer remains an important public health challenge that is growing in magnitude around the world”.
“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,” Dr Murray said.
Cancer second leading cause of death
For this study, the researchers analysed a number of risk factors linked with cancer — the second leading cause of death globally — including unsafe sex, dietary risks, air pollution, occupational risks, drug use, low physical activity, and other environmental risks.
Tracheal, bronchus, and lung cancer were identified as the leading cause of risk-attributable cancer deaths for both men and women around the world, collectively accounting for 36.9 per cent of all cancer deaths attributable to risk factors.
This was followed by colon and rectum cancer (13.3 per cent), oesophageal cancer (9.7 per cent), and stomach cancer (6.6 per cent) in men, and cervical cancer (17.9 per cent), colon and rectum cancer (15.8 per cent), and breast cancer (11 per cent) in women.
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, wrote: “The primary prevention of cancer through eradication or mitigation of modifiable risk factors is 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.”
On links between cancer risk and poverty, they wrote that it’s no accident that “behaviours associated with higher risk of cancer are patterned according to poverty, particularly within countries”.
“Poverty influences the environments in which people live, and those environments shape the lifestyle decisions that people are able to make,” Sarfati and Gurney wrote, adding that action to prevent cancer requires concerted effort within and outside the health sector.
“This action includes specific policies focussed on reducing exposure to cancer-causing risk factors, such as tobacco and alcohol, and access to vaccinations that prevent cancer-causing infections, including hepatitis B and HPV.”
(Edited by Amrtansh Arora)