LONDON — 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, the 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.

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