Cancer research: Half of cancer deaths worldwide are due to preventable risk factors | science and technology

Most cases of cancer are caused by preventable factors. As oncologist Josep Tabernero told EL PAÍS in 2017, “40% of tumors could be reduced by changing habits”. And he wasn’t on the wrong track. An international study published this Thursday in the journal The Lancet demonstrates the real impact of these carcinogens: in 2019, almost half of cancer deaths – a total of 4.45 million – were due to preventable 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 a key objective: “If Europeans under 20 stopped smoking tomorrow, cancer mortality would be halved in 50 years.

The researchers looked at data from the Global Burden of Disease, Injury, and Risk Factor (GBD) study, which examines 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 death and poor health from 23 types of cancer. They found that these risk factors explain 44.4% of cancer deaths worldwide. Half of all male cancer deaths, and more than a third in females, result from these potentially preventable elements.

There is the environment risk factors, such as pollution; behavioral, such as smoking, drinking alcohol, or having unprotected sex; and metabolic, such as a high body mass index or high blood sugar. But in the spotlight, tobacco, which fuels the appearance of up to 16 types of cancer. This is the most obvious risk factor, light years ahead of the second, alcohol, and the third, high body mass index. To see the impact of each, 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 premature 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 Bocsi (Bloomberg)

The researchers also found differences between men and women. Men are more exposed to these risk factors. 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 in men than in women. “, explain the authors. Similarly, disability-adjusted life years attributable to occupational carcinogens were also higher. This could indicate, the researchers add, “that men are more likely than women to be employed in workplaces with a high risk of exposure to carcinogens.”

A boom in metabolic risks

Despite the fact that these the risk factors are well known to oncologists and citizens, research warns that deaths associated with these preventable factors have increased by 20% over the past decade. And while tobacco continues to be the number one contributor to 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 increases with rates of obesity and overweight, which have exploded over the past 20 years. According to the Our World in Data repository, excess fat has risen from two million deaths in 1990 to five million in 2019. The scientific community has also warned that unhealthy diets and sedentary lifestyles that lead to obesity continues to rise, as do levels of overweight in adults and children. A survey by the Hospital del Mar Institute of Medical Research (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 varies greatly from country to country. But the highest disease burden is in the most developed countries. Despite better access to diagnosis, better treatments and higher survival rates, it makes perfect sense that the burden of this disease falls on wealthy countries, says Esteve Fernández, director of epidemiology, prevention and control of the disease. cancer at the Catalan Institute of Oncology: “Cancer is a chronic disease typical of developed countries, and this is where developing countries are heading. As a country develops, it moves from an infectious disease model to a chronic disease model.

The new study indicates that middle-income and low-income countries are in an “epidemiological transition”. Cancer-related deaths have increased in low- and middle-income countries over the past decade. “The increased cancer burden attributable to metabolic risk may be the result of these countries’ epidemiological transition, in which improvements in country-level development status are linked to increasing levels of obesity” , the researchers suggest in the paper.

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 the most of Europe. The DALY rate for behavioral factors, such as tobacco, alcohol, or unhealthy diets, is lowest in Scandinavian countries. The weight of metabolic risks, meanwhile, is greatest in the United States, parts of Latin America, the United Kingdom, and Eastern Europe.

Preventable deaths

Rodríguez assures that the study is “of high quality”. “It tells us indirectly which deaths are preventable. Forty-five percent of cancer deaths depend on risk factors that we could modify and therefore avoid. The other half of deaths, Rodríguez adds, point to other causes: from genetic inheritance to other unavoidable risk factors, such as aging. In fact, the researchers themselves point out in the article that the risk factors included in the study “are based on knowledge of cancer risk factors, but as knowledge expands, there may be other important risk factors to consider”. “In addition, there are known risk factors for cancer, such as sun exposure and infectious agents, such as Helicobacter pylori,” they add.

The researchers stress the need for “greater political commitment” to encourage health policies to prevent cancer. “Globally, substantial progress has been made in reducing tobacco exposure that can be linked to coordinated national and international prevention efforts. Interventions through fiscal 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 prevent tobacco-related deaths. “Its impact is between four and five times higher than the rest of the factors. The sad thing is that we don’t do anything, and the worst part is that you know what policies work, but governments don’t implement them. There is a gap between what we know works and what is practiced. Smoke-free legislation works well because it protects non-smokers and makes smokers think. We also know that the increase in price reduces the purchase of tobacco, as well as the control of advertising or the standardization of packaging. These are cheap measures,” pleads the expert, who also proposes increasing taxes on sugary drinks and removing vending machines selling unhealthy products from schools.

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