The leading cause of death in the United States is shifting from heart disease to cancer, but the transition is happening at varying paces across the country and affecting racial and ethnic groups differently, according to new Stanford research.
Overall, the news is good: cancer death rates dropped by 16 percent between 2003 and 2015, and mortality rates for heart disease fell even more - by 28 percent. If trends continue, cancer will supplant heart disease as the nation's leading killer, and it could happen as soon as 2020, according to the U.S. Centers for Disease Control and Prevention.
In the new study, which appears in the Annals of Internal Medicine, senior author Latha Palaniappan, MD, and her colleagues track the shift across the country through more than a decade of county-level mortality data covering all 50 states.
The change, which public health researchers have referred to as part of a fourth stage in an epidemiologic transition, signals the beginning of a new era. Years ago, in an earlier progression, chronic disease replaced infectious disease as the top cause of death in many nations. Now, with advances in preventive care and treatment for coronary conditions and risk factors, such as high blood pressure and diabetes, the threat of heart disease is becoming increasingly manageable.
The benefits appear to be reaching the wealthiest people first. An editorial accompanying the Stanford paper elaborates:
One aspect of the fourth stage of the epidemiologic transition has been described as the diseases of affluence being transformed into the diseases of poverty. This happened first for cardiometabolic disorders: At the beginning of the 20th century, they were considered to be "businessmen's diseases," but they became more common among disadvantaged persons by the end of the century, at least in high-income countries.
Palaniappan and her colleagues found the same effect in their analysis. Heart disease death rates decreased by 30 percent in high-income counties compared to 22 percent in low-income counties; while cancer mortality fell by 18 percent in the wealthiest areas compared to 11 percent in less affluent counties.
In 2015, heart disease continued to be the top killer in the lowest-income counties among all racial/ethnic groups; however, in the highest-income counties, cancer had become the leading cause of death among Asian-Americans, Hispanics and non-Hispanic whites, according to the study.
Additionally, the researchers found that blacks had the highest overall mortality rate, though they also showed the greatest improvements during the period studied. American Indians/Alaska Natives were the only group with an increased all-cause mortality rate between 2003 and 2015.
Palaniappan said she hoped the study would be helpful to identify geographic areas that could benefit most from enhanced public health efforts. "Prevention and treatment efforts aren't reaching all corners of the U.S. at the same time" she said, adding:
There are definitely pockets that we are missing. Thanks to the investments our nation has made in cardiovascular and cancer research over the past 50 years, we have made huge strides. We need to work harder to bring the benefits of this research to everyone in the U.S.
Some of the differences documented in the study could be explained by varying levels of health care access and by diverging trends in risk behaviors, such as smoking, Palaniappan said.
Regular recommended cancer screenings and other preventive tests (such as blood pressure, cholesterol and glucose screening) are essential to lowering cancer and heart disease risk, she said.
There are many ways for people on tight budgets to reduce their health risks, Palaniappan added: "The most cost-effective way to prevent both cancer and heart disease is to stop smoking, exercise and eat nine servings of vegetables and fruit daily."
Photo by leonie wise