In rich countries, cancer kills more than cardiovascular disease, researchers said in two studies, released Tuesday. In the future, this trend is likely to spread in the coming years to developing countries, turning cancer into the leading cause of death in the world.

While cardiovascular disease remains the leading cause of death in the world for middle-aged adults, cancer is becoming the leading cause of death in rich countries, according to two surveys released Tuesday. It is even "likely that cancer will become the most common cause of death in the world in a few decades," according to the researchers.

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Heart disease accounts for more than 40% of deaths, or about 17.7 million deaths in 2017. The authors, whose work is presented at the Congress of the European Society of Cardiology (ESC) in Paris, point to the heavy toll paid by poor countries to these pathologies.

Cancer, the second most common cause of death in the world in 2017, accounts for just over one-quarter (26%) of all deaths. But in rich countries, cancer now kills more people than heart disease, according to research, limited to 21 countries, published in the medical journal The Lancet.

A new stage in health

The four high-income countries taken into account are Canada, Saudi Arabia, Sweden and the United Arab Emirates. "The world is witnessing a new epidemiological transition (...), cardiovascular disease is no longer the leading cause of death in high-income countries," said Gilles Deganais, professor emeritus at Laval University, Quebec and co-author of both publications.

But as global rates of heart disease decline, cancer could become the leading cause of death worldwide "in the next few decades," he says.