A new study found that cancer now kills more people than heart disease in wealthy countries, and is on track to become the world’s biggest killer within just a few decades.
Cardiovascular disease (including heart failure, angina, heart attack and stroke) accounts for 40 per cent of all deaths, remaining the leading cause of mortality among middle-aged adults worldwide, researchers said.
However, this is no longer the case in wealthy countries, where cancer kills roughly twice as many people as heart disease.
The research was part of the Prospective Urban and Rural Epidemiologic (PURE) study, published in The Lancet and presented at the ESC Congress in Paris on Tuesday.
The countries analyzed included Argentina, Bangladesh, Brazil, Canada, Chile, China, Colombia, India, Iran, Malaysia, Pakistan, Palestine, Philippines, Poland, Saudi Arabia, South Africa, Sweden, Tanzania, Turkey, United Arab Emirates and Zimbabwe.
“Our report found cancer to be the second most common cause of death globally in 2017, accounting for 26 per cent of all deaths,” said Gilles Dagenais, one of the study’s lead researchers. “But as [heart disease] rates continue to fall, cancer could likely become the leading cause of death worldwide within just a few decades.”
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Of an estimated 55 million deaths in the world in 2017, around 17.7 million were due to cardiovascular disease.
Around 70 per cent of all cardiovascular cases and deaths are due to modifiable risks such as high blood pressure, high cholesterol, diet, smoking and other lifestyle factors.
In high-income countries, common treatment with cholesterol-lowering statins and blood-pressure medicines have helped bring rates of heart disease down dramatically in the past few decades.
Dagenais’ team said their findings suggest that the higher rates of heart-disease deaths in low-income countries may be mainly due to a lower quality of healthcare.
The research found first hospitalization rates and heart disease medication use were both substantially lower in poorer and middle-income countries than in wealthy ones.
Can you prevent cancer?
In 2015, the researchers estimated that nearly 70,000 cancer cases across Canada were likely attributable to things like diet choices, exercise, air pollution and other preventable risk factors.
The researchers think there could be 102,000 preventable cases of cancer in Canada by 2042, given current trends in these risk factors combined with an aging population.
“Many Canadians are not aware that their lifestyle can have such a dramatic impact on their eventual cancer risk and that Canadians can take action to reduce their personal risk of cancer,” Dr. Darren Brenner, co-author of the study, previously told Global News.
Here are the top preventable risk factors for cancer, according to the research:
Smoking is responsible for about 72 per cent of lung cancers and 74 per cent of cancers of the larynx, the researchers found. But it’s also responsible for a significant percentage of colorectal, liver, stomach and kidney cancers.
“Tobacco is still by far and away the leading preventable cause of cancer. It accounts for actually almost half of all the preventable cancer cases in our study,” Brenner said.
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One of the most important things you can do to reduce your cancer risk is to live smoke-free, according to Elizabeth Holmes, policy analyst with the Canadian Cancer Society.
“Smoking rates are decreasing, but it still remains the number 1 preventable cause of cancer and it really speaks to the importance of continued work in tobacco control measures,” she said.
Physical inactivity is the second-largest preventable risk factor for cancer. It contributes to lung, colorectal, liver, oral, stomach, kidney, bladder and breast cancers, said researchers.
Sedentary behaviour — spending a lot of time not moving at all — is a little different but also contributes to cancer risk, Brenner said.
“There is something about being sedentary. There is something about being obese that is associated with an increased risk of cancer but is not necessarily a cause and effect,” said Dr. David Price, a family physician and chair of the department of family medicine at McMaster University.
The Canadian Cancer Society recommends “move more, sit less” as a good way to cut your cancer risk.
Excess weight contributed to 7,200 new cancer cases in 2015, according to the research. The researchers expect this to nearly triple by 2042 and overtake physical inactivity as the second-most common preventable cause of cancer behind smoking.
If more Canadians had a healthy body weight — defined as a body mass index of at most 25 kg/m2 — about 110,600 cancer cases could be prevented by 2042, the researchers said.
“We don’t have recent numbers on how aware people are but, in the last 10 years, we saw that only about a third of people were aware of the link between excess weight and cancer risk,” Holmes said. “So, certainly, this is an opportunity to raise that awareness.”
Diets low in fruits and vegetables and diets high in processed meats and red meat all contribute to cancer risk, according to the research. They’re associated with lung, liver, colorectal and pancreatic cancers.
That’s why the Canadian Cancer Society recommends “eating well” as a good way to help decrease your cancer risk.
Alcohol is also associated with a large number of cancer cases, including 18 per cent of cancers of the oral cavity and pharynx as well as colorectal, liver, larynx, stomach, pancreatic and breast cancers.
The sun is associated with skin cancer — which, unfortunately, is the most common kind of cancer.
Practising sun safety by doing things like wearing a hat or long sleeves in the sun and properly using sunscreen could cut your risk of this preventable cancer, according to the Canadian Cancer Society.
Prevention isn’t everything
Cancer isn’t a perfect cause and effect as many cancers aren’t preventable, Holmes said.
“The findings of the study are that about four in 10 cancers can be prevented,” she said. “Which means that about six in 10 cancers cannot be prevented. There are things that we cannot change, like our age, sex, genetics and family history, that influence our cancer risk.”
By changing your lifestyle through healthy eating, exercise and quitting smoking, you can still cut your risk of cancer, though, Holmes said.
“What these results are not saying (is) that making changes to risk doesn’t mean that you won’t get cancer,” Brenner said. “But it also means that your chance of getting (the) disease is lower.”
— With files from Kate Kelland, Reuters and Leslie Young, Global News