Cancer will soon kill more Americans than heart disease—except in low-income areas

Different incomes, different causes of death.
Different incomes, different causes of death.
Image: Reutes/David Gray
We may earn a commission from links on this page.

Roughly 50 years ago, an epidemiologist named Abdel Omran published a theory that suggested that as a country develops, the way its people die changes, too.

According to the theory, when countries are still developing, problems like malnutrition, infectious disease, and maternal mortality tend to be significant causes of death, which leads to consequences including shorter life expectancies. As nations become wealthier, life expectancies tend to be longer as people attain more nutritious food, hygiene, and higher qualities of life in general. The leading causes of death tend to shift to non-communicable diseases, like cancer, diabetes, respiratory disease, or heart disease. This theory has played out in the US, parts of Europe, China, and Mexico, and shows that diseases are often directly linked to socioeconomic factors.

But it seems that there can even be changes within these non-communicable causes of death as different parts of a country change at different rates. New research (paywall) from scientists at Stanford Medical School suggests that in the US, the leading cause of death is slowly shifting to be cancer instead of heart disease—particularly in wealthy counties. In low-income counties, deaths related to heart disease remain much higher. This work suggests that people living in low-income areas of high-income countries need different public health policies and interventions than those living in wealthier areas—something policymakers should keep in mind as they try to lower death rates even further.

The team, led by Latha Palaniappan, an internist at Stanford, combed through the death certificates from the National Center for Health Statistics for over 32 million people living in America between 2003 and 2015. They broke down median household incomes for each county from the middle years 2007 to 2011, and put them into five categories. The lowest group had incomes ranging from about $19,340 to $36,400, and the highest group had median incomes above $52,461.

During the study timeframe, the annual death rate dropped from 823 per 100,000 people to 734 per 100,000 people. Deaths related to heart disease and cancer also decreased, but at different rates: Whereas the heart disease death rate fell from 229 deaths per 100,000 people to about 166 deaths per 100,000 people, cancer deaths only fell from 187 per 100,000 to 157 per 100,000.

The authors hypothesize that this change results from more efforts to prevent the risk factors for heart disease, including drinking, smoking, high blood pressure, and high glucose levels.

“We’re just on the cusp of the transition from heart disease to cancer as the leading cause of death,” Palaniappan told CNN. At the moment, heart disease is the number one killer in the US, accounting for about 25% of all fatalities, but the US Centers for Disease Control predicts that cancer may take its place by 2020.

However, the drops in death rates for heart disease were most pronounced in counties with the highest incomes. In the lowest-income counties, the 2015 death rate was almost the same as the 2003 rate for the richest counties.

The poorest counties also had more cancer deaths than the richest, but the difference was less pronounced. The highest-income counties only had about 10 fewer deaths related to cancer in 2015 than the lowest-income counties.

It’s likely not just income that plays a factor in shifting death rates; ethnicity does as well. Over the 13 years of study cancer killed more white, Hispanic, and Asian Americans than heart disease; blacks and Native Americans saw higher instances of deaths from heart disease. Minorities, particularly African-American people, tend to receive lower-quality healthcare throughout their lives, which likely plays a role in developing heart disease later on in life.

In an accompanying commentary, scientists working at Geneva University Hospitals in Switzerland write that (paywall) the epidemiological shifts present in the US are a shift toward an age of degenerative diseases—specifically, ailments like cancer or neurodegenerative diseases.

In a lot of ways, this is a great trend; it means most people are living long enough to become sick, and new therapies for both heart disease and cancer are proving to be effective. However, it also means that a lot of these advances in treatments have remained inaccessible for people in low-income areas so far. “We need to work harder in lower-income areas of the US so they can see the same improvements in mortality,” Palaniappan told CNN.