Nearly half of cancer deaths are preventable

Tobacco tax increases and advertising bans have helped reduce the number of people exposed to tobacco use.Credit: Justin Tallis/AFP/Getty

Nearly 50% of cancer deaths worldwide are caused by preventable risk factors, such as smoking and alcohol consumption, according to the largest study on the link between cancer burden and risk factors1.

Using estimates of cancer cases and deaths in more than 200 countries, researchers found that preventable risk factors were responsible for nearly 4.5 million cancer deaths in 2019 (see “Cancer Deaths in the World). world “). This represents more than 44% of cancer deaths worldwide that year. Smoking, alcohol consumption and a high body mass index (BMI) – which can indicate obesity – were major contributors to cancer.

Global cancer deaths: bar chart showing the number of women and men who died from cancer in 2019.

Source: Ref 1.

The findings, published in The Lancet on August 20, largely confirm the results of smaller studies and highlight how reducing exposure to risk factors could help prevent a substantial proportion of cancers, says Rudolf Kaaks, cancer epidemiologist at the German Center for Cancer Research. cancer in Heidelberg. The take-home message is simple: “Don’t smoke,” says Kaaks. “Don’t be overweight and don’t drink too much alcohol.”

Heavy burden

The true number of cancer cases and deaths worldwide is difficult to determine because some countries do not record such data, says study co-lead author Justin Lang, an epidemiologist at the Health Agency. Public Health Canada in Ottawa. To overcome this, Lang and his colleagues used data from a study of death and disability from more than 350 illnesses and injuries in 204 countries. From these data, they estimated the impact of 34 risk factors on poor health and death from 23 types of cancer (see “Cancer Deaths by Tumor Type”).

Cancer deaths by tumor type: Bar chart showing the top eight cancer types by cause of death.

Source: Ref 1.

In 2019, half of all male cancer deaths, and more than a third of female cancer deaths, were due to preventable risk factors, including tobacco and alcohol use, unhealthy diet, relationships unprotected sex and workplace exposure to harmful products, such as asbestos. From 2010 to 2019, global cancer deaths caused by these risk factors increased by approximately 20%, with excess weight accounting for the largest percentage increase, particularly in low-income countries.

“These results, combined with local knowledge, may be useful to decision-makers in determining which modifiable risk factors to target in cancer control planning efforts,” says study co-author Kelly Compton, lead project at the Institute for Health at the University of Washington. Metrics and Evaluation (IHME) in Seattle.

Smoke-free policies, increased tobacco taxes and advertising bans have been shown to reduce exposure to tobacco use, and similar efforts have been recommended to help reduce excessive alcohol consumption, says the co -lead author Lisa Force, who studies cancer burden and health outcomes at the University of Washington.

Future research

The study did not include some other known risk factors for cancer, including exposure to ultraviolet (UV) light and certain infections. Although researchers have used “unprotected sex” as an indicator of cancer risks associated with human papillomavirus (HPV) and other sexually transmitted viruses. Cervical cancer, caused by certain strains of HPV, is the leading cause of cancer death among women in sub-Saharan Africa. There, says Kaaks, “much of the cancer incidence and mortality in women could be reduced by timely HPV vaccination.”

The team could include risk factors such as infections and exposure to UV rays in future analyses, again data – for example on levels of exposure to these factors – are available, says the co -author Jonathan Kocarnik, who models the global cancer burden at IHME.

Future work could help assess the effects of the COVID-19 pandemic on cancer cases and deaths. A 2020 study2 estimated that, by 2025, there will be more than 3,000 preventable cancer deaths in England due to diagnostic delays due to COVID-19. In some regions, Kocarnik says, the pandemic may have changed people’s exposure to certain risk factors: for example, workplace exposure to harmful products may have decreased during shutdowns. However, he adds, “potential changes in risk factor exposures and impact on future cancer burden will likely take many years to fully understand.”

Nearly half of cancer deaths are preventable

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