According to Dr David S Jones, Dr Scott H Podolsky, and Dr Jeremy A Greene (2012) of the New England Journal of Medicine, the top ten causes of death in the US changed significantly between 1900 and 2010. The chart below contrasts the times.
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Sadly, heart disease and cancer claim more lives today than ever, despite the fact that deaths from pneumonia, influenza, tuberculosis, and gastrointestinal infections have declined dramatically over the past century. While modern medicine has reduced the risks of infectious diseases, the reality of obesity and carcinogens in today's society has created new risks for society in the 21st century.
Source: Jones, D S; Pololsky, S H; & Green, J A (2012, June 21), The Burden of Disease and the Changing Task of Medicine, New England Journal of Medicine.