Cancer overtakes heart disease as biggest killer in wealthy countries

Cardiovascular disease remains the leading cause of mortality among middle-aged adults globally, accounting for 40 per cent of all deaths — but that's no longer the case in high-income countries.

Common medications have helped bring rates of heart disease down dramatically

In high-income countries, treatment with cholesterol-lowering statins and blood-pressure drugs have helped bring rates of heart disease down dramatically in the past few decades. (Guillaume Souvant/AFP/Getty Images)

Cancer has overtaken heart disease as the leading cause of death in wealthy countries and could become the world's biggest killer within just a few decades if current trends persist, researchers said on Tuesday.

Publishing the findings of two large studies in The Lancet medical journal, scientists said they showed evidence of a new global "epidemiologic transition" between different types of chronic disease.

While cardiovascular disease remains, for now, the leading cause of mortality worldwide among middle-aged adults — accounting for 40 per cent of all deaths — that is no longer the case in high-income countries, where cancer now kills twice as many people as heart disease, the findings showed.

"Our report found cancer to be the second most common cause of death globally in 2017, accounting for 26 per cent of all deaths. But as [heart disease] rates continue to fall, cancer could likely become the leading cause of death worldwide, within just a few decades," said Gilles Dagenais, a professor at Quebec's Laval University in Canada who co-led the work.

Of an estimated 55 million deaths in the world in 2017, the researchers said, around 17.7 million were due to cardiovascular disease — a group of conditions that includes heart failure, angina, heart attack and stroke.

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.

Hospitalization rates for heart disease were substantially lower in poorer and middle-income countries than in wealthy ones. (Kim Kyung Hoon/Reuters)

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's 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.

Improve education for impact

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.

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. 

Despite including as many as 21 countries, the researchers said to exercise caution in generalizing the results to all countries, particularly since they lacked data from west Africa, north Africa or Australia with few participants from the Middle East.

The effect of risk factors such as poor diet and household air pollution varied by the economic level of the countries, the journal's editors said. Global health policies should be adapted to different groups of countries based on factors such as the expected benefit and access to health care.

Stephanie Read of Women's College Research Institute in Toronto and Sarah Wild of the University of Edinburgh, U.K., wrote a journal commentary published with the research.

"[T]heir findings can inform the effective use of limited resources — for example, by indicating the importance of improving education across the world and improving diet and reducing household air pollution in less developed countries. The value of collecting similar data to inform policy in a wider range of countries is clear, while improving lifestyle choices and modifying their social and commercial determinants remain a challenge," Read and Wild wrote.

They said the findings suggest that improving education in low-income countries and middle-income countries might be expected to have a larger effect on mortality than reducing prevalence of diabetes, abdominal obesity, depression, or low physical activity.

Jeremy Pearson, associate medical director at the British Heart Foundation, said heart and circulatory diseases remain the leading cause of death and disability worldwide.

As the population grows and ages, more people can expect to survive heart attacks and strokes, and the number of people living with the debilitating after-effects of the two conditions will continue to rise, Pearson said in an email calling for research into the prevention, treatment and cures for all heart and circulatory diseases.

With files from CBC News


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