Cancer will soon be the leading cause of death in the United States, according to a new report.

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Researchers recently conducted a study, published in the Annals of Internal Medicine journal, to explore data that suggests cancer will surpass heart disease as the leading cause of death in America.

To do so, they examined the death records of more than 32 million adults, aged 25 and older, across 3,143 American counties between 2003 and 2015. They assessed their medical information, income, race and other demographic data and followed them for about 13 years.

After analyzing the results, they found heart disease was the leading cause of death for 79 percent of counties in 2003, while cancer was the leading cause in the others. In 2015, heart disease was the leading cause of death for 59 percent of counties, with cancer being the leading cause in the remaining.

Overall, the heart disease mortality rate decreased by 28 percent between 2003 and 2015, and the cancer mortality rate dropped by 16 percent.

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However, upon further investigation, they discovered cancer deaths may be more on the rise in higher income counties. Heart disease deaths declined by 30 percent in high-income counties, while low-income counties experienced a 22 percent drop. A similar pattern was apparent for cancer deaths as the threat fell by 18 percent in high-income counties and by 11 percent in low-income ones.

“Data show that heart disease is more likely to be the leading cause of death in low-income counties,” the authors wrote. “Low-income counties have not experienced the same decrease in mortality rates as high-income counties, which suggests a later transition to cancer as the leading cause of death in low-income counties.”

They also noted patterns among racial and ethnic groups. Cancer replaced heart disease as the leading cause of death for Asian-Americans, Hispanics and whites. That was not the case for American Indians/Alaska Natives or blacks.

While the mechanisms behind the shifts in mortality rates are unclear, the scientists believe differences in smoking, obesity and diabetes trends between high and low income groups could be factors.

As they continue their research, they are encouraging individuals to undergo recommended cancer screenings and practice healthy lifestyles.

Read more about the findings here.

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