Chronic diseases such as heart disease and diabetes are serious health concerns by themselves, but to make matters worse, they may also raise a person's risk of cancer, a new study from Taiwan finds.
The researchers found that several common chronic diseases, such as lung disease and diabetes, or markers for those diseases, such as high cholesterol levels as a marker for heart disease, were each linked with an increased risk of developing cancer or dying from cancer.
What's more, the study estimated that together, these chronic diseases and markers accounted for about 20 percent of new cancer cases, and 39 percent of cancer deaths, among the study participants. That's about as much as five lifestyle factors combined — smoking, alcohol consumption, obesity, unhealthy diet and lack of exercise — contribute to cancer development and death.
"Chronic disease is an overlooked risk factor for cancer, as important as five major lifestyle factors combined," the researchers wrote in the study, which was published yesterday (Jan. 31) in the journal The BMJ. [10 Celebrities with Chronic Illnesses]
But there may be a way to lower that risk: The study also found that regular exercise was linked with a 40-percent reduction in the cancer risk tied to chronic diseases.
Previous studies have shown that certain chronic diseases are associated with a modest increase in the risk of cancer, but most of those studies examined only a single chronic disease at a time, the researchers said. However, chronic diseases are usually clustered (for example, adults with diabetes often have heart disease as well), so there was a need to look at the joint impact of chronic diseases on cancer risk, the authors of the new study said.
The new study involved more than 405,000 men and women in Taiwan who did not have a history of cancer at the start of the study. The participants answered questions about their medical history, lifestyle behaviors and demographics, and they underwent a series of medical tests, including blood and urine tests and a physical exam.
The researchers then evaluated the participants for several chronic diseases or disease markers, including heart disease markers, diabetes, chronic kidney disease markers, pulmonary disease and gout (a form of arthritis). The participants were followed for about nine years to assess whether they developed cancer or died from the disease.
The study found that each of these chronic diseases or markers was individually linked with a 7- to 44-percent increased risk of developing cancer, and a 12- to 70-percent increased risk of dying from cancer.
The researchers also gave the participants a "chronic disease risk score" based on the diseases or disease markers they had, and how much these diseases or markers contributed to cancer risk. The participants with the highest scores had about a twofold increase in their risk of developing cancer and a fourfold increase in their risk of dying from cancer.
High chronic disease risk scores were also linked with a 13-year reduction in life span for men and a 16-year reduction in life span for women.
The findings suggest that chronic diseases should be considered when developing new cancer-prevention strategies.
In addition, the findings could have implications for the management of chronic diseases. "Recognizing the substantial reduction in lifespan and increase in cancer risk associated with non-cancer chronic diseases could be used as a 'teachable moment' to stimulate motivation for better management of such diseases," the researchers wrote.
Original article on Live Science.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.