Heart disease still claims the lives of more people globally, but in more affluent nations it has now ceded its place as the leading killer to cancer, a major new report finds.
Around the world, 40 percent of all deaths are caused by heart disease, making it the number one global killer. That means that of the estimated 55 million people who died around the world in 2017, approximately 17.7 million succumbed to heart disease.
Cancer was the second leading killer globally, accounting for 26 percent of all deaths, the study authors said.
However, when middle- and lower-income countries were taken out of the calculation, a different picture emerged, according to a report published online Sept. 3 in The Lancet.
For people living in "high-income" countries such as Canada, Sweden and Saudi Arabia, heart disease represented just 23 percent of deaths, while cancer was to blame for 55 percent of deaths, the researchers said.
The findings come from a global study of more than 162,500 middle-aged people living in four high-income countries, 12 countries considered middle-income, and five low-income countries. The study was led by Dr. Gilles Dagenais, emeritus professor at Laval University in Quebec, Canada.
Speaking in a journal news release, Dagenais said that the world is undergoing a "transition" in terms of causes of death, "with cardiovascular disease no longer the leading cause of death in high-income countries."
But as better prevention and treatment of heart disease becomes more common, and cases of the disease "continue to fall, cancer could likely become the leading cause of death worldwide, within just a few decades," Dagenais said.
Study principal investigator Dr. Salim Yusuf, a professor of medicine at McMaster University in Canada, agreed that "long-term cardiovascular disease prevention and management strategies have proved successful in reducing the burden in high-income countries."
But poorer nations often lack either the resources or leadership to tackle high rates of heart disease, he added, so "governments in these countries need to start by investing a greater portion of their gross domestic product in preventing and managing non-communicable diseases, including cardiovascular disease, rather than focusing largely on infectious diseases."
A second report focused on why people around the world continue to die in great numbers from heart disease. The same team of researchers used data on almost 156,000 middle-aged people to look at the role played by 14 heart disease risk factors.
The good news: 70 percent of the factors driving heart disease and heart disease death are "modifiable," meaning changes to lifestyle and environment can greatly lessen people's risk. Some of those factors include "metabolic" ones -- overweight, diabetes and the like -- or high blood pressure. In poorer countries, environmental factors, such as air pollution or poor diets, play a greater role.
The study was also presented Tuesday at the annual meeting of the European Society of Cardiology, in Paris.