There's a New No. 1 Killer in the Rich World

Cancer is now the No. 1 cause of death in wealthy countries, killing twice as many people as heart disease—which remains the leading cause of death for middle-aged adults worldwide, Reuters reports. A new study finds that this "epidemiological transition" is at play in "rich world" countries including Sweden, Canada, Chile, Argentina, Poland, and Turkey; researchers theorize that could be due to improvements in prevention and treatment of heart disease in those countries, CNN reports. "As cardiovascular disease declines in many countries, cancer mortality is likely to become the leading cause of death in the future" across the globe, the study's senior author says, per Fox News.

Overall, cardiovascular disease (a group of ailments including heart failure, angina, heart attack, and stroke) kills 40% of all adults aged 35-70 worldwide, with cancer in the No. 2 spot at 26%, the study found. But in high-income countries, the prevalence of cholesterol-lowering statins and blood pressure medication has brought cardiovascular disease rates down significantly. In middle-income and low-income countries, researchers found heart disease medication use was much lower. Among the study's limitations, however, is the fact that it did not look at every country in the world. The US was not included, but a study last year found that while heart disease was more likely to kill those in low-income US counties, cancer was more likely to kill those in high-income counties. (More cancer stories.)