Half of cancer deaths in the world are due to preventable risk factors

Half of cancer deaths in the world are due to preventable risk factors

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Some of the causes of cancer have names and surnames. Not all of them, but most of them, yes. Name, surnames and medicine. Because they are avoidable, as the oncologist Josep Tabernero already recalled in 2017 in an interview with EL PAÍS: “By changing habits, 40% of tumors could already be reduced.” And he wasn’t on the wrong track. An international study published this Thursday in the journal The Lancet draws the real impact of these carcinogens: almost half of the cancer deaths that occurred in the world in 2019 (4.45 million), are due to avoidable risk factors, such as tobacco, alcohol, obesity, pollution, unhealthy diets or occupational exposure to harmful elements such as asbestos, among others. A few months ago, another oncologist, Frenchman Thierry Philip, pointed to the target of the great enemy: “If Europeans under 20 years of age stopped smoking tomorrow, cancer mortality would be halved in 50 years.”

The researchers reviewed data from the Global Burden of Disease, Injury, and Risk Factor (GBD) Study, which looks at 369 causes of death and disability and 87 risk factors for 204 countries and territories. Specifically, they focused on studying the impact of 34 risk factors on deaths and poor health from 23 types of cancer and found that, indeed, these risk factors explain 44.4% of cancer deaths in the world . More in men than in women: half of all male deaths from cancer and more than a third of deaths from oncological processes in women have these potentially preventable elements as their starting point.

There are environmental risk factors, such as pollution; behavioral, such as smoking, drinking alcohol, or having unsafe sex; and metabolic, such as high body mass index or high blood glucose levels. But in the spotlight is, especially, tobacco, which fuels the appearance of up to 16 types of cancer. It is the most determining risk factor, light years ahead of the second, alcohol, and the third, high body mass index, which is associated with overweight and obesity. To see the impact of each of them, the researchers used the disability-adjusted life years (DALY) indicator, which measures the global burden of disease and expresses the years lost due to illness, disability or early death. The age-standardized DALY rate for tobacco was 677.3 years lost per 100,000 population/year, while the rate for alcohol was 155 and for high body mass index, 134.

A waitress serves alcoholic drinks on a terrace in Berlin on August 9.Krisztian BocsiBloomberg

The researchers also found differences between men and women: they are more exposed to these risk factors and the burden of disease translates into more years lost due to disease, disability or premature death caused by cancer. There was a disparity in DALYs attributed to smoking and alcohol consumption, much higher in men, “which could be due to greater exposure to these behavioral risk factors among men than among women,” the authors explain. Likewise, the disability-adjusted life years attributable to carcinogens at work were also higher in them, which could indicate, the researchers add, “that men are more likely than women to be employed in workplaces with higher risk of exposure to carcinogens.

Metabolic risk boom

Despite the fact that these risk factors are well known to oncologists and citizens, research warns that deaths associated with these preventable factors have increased by 20% in the last decade. And while tobacco continues to lead as the biggest driver of cancer, metabolic risks accounted for the largest percentage increase in cancer deaths and ill health, with deaths increasing by 34.7%.

The weight of metabolic factors grows along with obesity and overweight rates, which have skyrocketed in the last 20 years: according to the data repository Our World in Data, excess fat has gone from being the cause of two million deaths in 1990 to reach five million in 2019. The scientific community has also warned that unhealthy diets and sedentary lifestyles that lead to obesity continue to rise, as do overweight levels in adults and children . An investigation by the Hospital del Mar Medical Research Institute (IMIM) in Barcelona concluded in 2019 that eight out of 10 men and 55% of women will be overweight or obese in 2030.

Customers at a McDonald's chain restaurant in London last July.
Customers at a McDonald’s chain restaurant in London last July.HANNAH MCKAY (Reuters)

The situation, by country, is highly variable. But the highest burden of disease is in the most developed states. Despite having more access to diagnosis, better treatments and higher survival rates, it makes perfect sense that the burden of this disease falls on rich countries, explains Esteve Fernández, director of Cancer Epidemiology, Prevention and Control at the Catalan Institute of Oncology: “Cancer is a chronic disease typical of developed countries and it is where developing countries are headed. As a country grows, it evolves from a pattern of infectious diseases to a pattern of chronic diseases.”

Precisely, the research points out, middle-income or low-income countries are in full “epidemiological transition”: although in 2019 the weight of years of life lost attributable to cancer risk factors used to increase in rich countries, seeing the evolution of the last decade, these DALY rates fell in the most developed territories and the values ​​increased in the low-middle income countries. “The increased burden of cancer attributable to metabolic risk could be the result of these countries undergoing an epidemiological transition in which improvements in country-level development status are related to rising levels of obesity,” researchers weigh in the article.

On the map that draws the weight of risk factors in the burden of disease and the years lost due to tumors, Spain is halfway between the worst and the best in all indicators. In the middle, explains César Rodríguez, vice president of the Spanish Society of Medical Oncology: “We are not at the forefront of anything, but we are second in everything. Even in metabolic factors, for example, such as obesity or being overweight. The myth of the Mediterranean diet is very good, but there are countries better than us. It seems that we are adopting customs and habits that are similar to countries that are worse off than us.”

The age-adjusted DALY ratio for environmental and occupational factors, such as exposure to pollution or carcinogens such as asbestos, cadmium or chromium, is skyrocketing in China and almost all of Europe (except Spain, Portugal, Ireland and some countries from the center of the continent). The DALY ratio for behavioral factors, such as tobacco, alcohol or unhealthy diets, are low in the Scandinavian countries, while in Eastern Europe and Argentina, for example, they show the highest thresholds; Spain, France, Italy, UK and North America are just behind the highest levels. The weight of metabolic risks, meanwhile, is shown more harshly in the United States, part of Latin America, the United Kingdom and Eastern Europe.

preventable deaths

Rodríguez assures that the study is “of high quality”: “And it comes to tell us indirectly what the avoidable deaths are. 45% of cancer deaths depend on risk factors that we could modify and, therefore, avoid”. The other half of deaths, adds Rodríguez, point to other causes: from hereditary, to other non-preventable risk factors, such as aging, or variables yet to be known. In fact, the researchers themselves point out in the article that, among its limitations, apart from the data collection itself, which is more or less complex depending on the country, is that the risk factors included in the study “are based on knowledge of cancer risk factors, but as knowledge expands, there may be additional important risk factors to incorporate” into other updates to the GBD, they note. “In addition, there are known risk factors for cancer, such as exposure to sunlight (i.e., ultraviolet radiation) and infectious agents, such as Helicobacter pyloriwhich are not included in the GBD study”, they add.

The researchers point to the need for “more political commitment” to encourage health policies to prevent cancer. “Globally, there has been substantial progress in reducing tobacco exposure that can be linked to coordinated national and international prevention efforts. Interventions through tax and regulatory policies for tobacco use, including smoke-free policies, increased tobacco taxes, and advertising bans (…) have played an important role in these efforts. Similar efforts, including taxes and advertising bans, have been recommended to help reduce the harmful use of alcohol.

Fernández assures that there is still a long way to go to continue winning spaces and lives to tobacco. “Its impact is between four and five times higher than the rest of the factors. The sad thing is that we do nothing and the worst thing is that you know what policies work, but the governments do not implement them. There is a gap between what we know works and what is put into practice: smoke-free legislation works well because it protects non-smokers and makes smokers think about it. We also know that raising the price decreases the purchase of tobacco and controlling advertising or making plain packaging. They are cheap measures”, defends the expert, who also proposes increasing taxes on sugary drinks or removing vending machines with unhealthy products from schools.

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