The same lifestyle habits that protect the heart can also curb the risk of a range of cancers, a large new study confirms.
The study of more than 20,000 U.S. adults found both bad news and good news.
People with risk factors for heart disease also faced increased odds of developing cancer over the next 15 years. On the other hand, people who followed a heart-healthy lifestyle cut their risk of a cancer diagnosis.
Experts said the findings are no surprise. The American Cancer Society (ACS) has estimated that close to half of cancer deaths in the United States are linked to modifiable factors -- including poor diet, smoking, lack of exercise and obesity.
But the study drives home an important message, according to Marjorie McCullough, senior scientific director for epidemiology research at the ACS.
"A healthy lifestyle can reduce your risk of the top two killers in the U.S.," said McCullough, who was not involved in the study.
Lead researcher Dr. Emily Lau made another point: People often think of diet and exercise as being good for the heart -- but may not always recognize their roles in cancer risk.
"When we're counseling patients, we should be talking about that," said Lau, a cardiologist at Massachusetts General Hospital in Boston.
She and her colleagues reported their findings Mar. 16 in the journal JACC: CardioOncology.
The results are based on 20,305 Americans who were 50 years old, on average, when the study began. Lau's team looked at how well they were adhering to the American Heart Association's "Life's Simple 7."
Those recommendations advise people to:
Researchers gave each participant up to 2 points per goal, depending on how well they were doing with it.
In the end, people who scored high on the heart-health scale were also less likely to develop cancer over the next 15 years: For each point they received, their risk of a future cancer declined by 5%.
The story was different for people who had major risk factors for heart disease at the study's start -- including high blood pressure, diabetes, high cholesterol and smoking. Those deemed to be at high risk of a heart attack in the next 10 years were over three times more likely to develop cancer compared to people with a low heart attack risk.
McCullough said the AHA recommendations on diet, weight, exercise and smoking largely align with advice from the cancer society.
But the ACS also stresses the role of alcohol in some cancers, including throat, esophageal, liver, breast and colon cancers. Drinking accounts for about 6% of all U.S. cancers, the society estimates.
"It's best to avoid alcohol," McCullough said.
As for exercise, the ACS encourages people to do a bit more -- ideally logging more than 300 minutes each week. But the most important step, according to McCullough, is to get off the couch, since sedentary people can see health benefits from becoming regularly active to some degree.
McCullough pointed to a simple mantra: "Move more, sit less."
Cancer, of course, is many diseases, and the risk factors vary according to the type, McCullough noted. Obesity, for example, is more closely linked to certain cancers -- such as uterine, breast and esophageal cancers -- than others.
In this study, the modifiable risk factor that made the biggest difference in overall cancer risk was smoking. That, Lau said, underscores the importance of helping smokers quit -- both for cancer prevention and the sake of their hearts.
The American Heart Association has more on Life's Simple 7.
SOURCES: Emily Lau, MD, cardiologist, Massachusetts General Hospital, Boston; Marjorie McCullough, ScD, RD, senior scientific director, epidemiology research, American Cancer Society, Atlanta; JACC: CardioOncology, March 16, 2021, online