A new study finds men who were fit in middle age were less likely to die from lung or colorectal cancer later in life.
While exercising has long been promoted for its heart health benefits, a new study published online in the journal JAMA Oncology is the latest to connect fitness with better outcomes for certain types of cancer.
The study found that men who were physically fit at midlife had a lower risk for lung and colorectal cancer than those who were unfit.
Participants who were in the top 40 per cent for heart-lung fitness had a 55 per cent lower rate of lung cancer and a 44 per cent lower risk of colorectal cancer compared to men in the lowest 20 per cent for fitness. For men who had cancer at the start of the study, researchers found a 32 per cent reduction in cancer-related deaths in those with the best fitness levels versus those with the worst.
“This study in particular shows that if we do measure fitness [in the clinic] it will give us information about a person’s future risk of cancer,” says researcher Susan Lakoski, MD, a cardiologist in the haematology-oncology department at the Vermont Cancer Centre of the University of Vermont, Burlington. The results revealed only an association between fitness level and cancer risks, not a direct causal relationship.
Researchers reviewed data from an on-going heart health study along with data from the Vermont study of nearly 14,000 men. Participants took a fitness test on a treadmill before the age of 65 and had started Medicare afterward, which allowed researchers to see their health outcomes.
Although most cancer findings were positive for patients who were more fit, the researchers did find a 22 per cent increase in prostate cancer risk for the fittest patients. Because of the overall drop in risks of dying from cancer, researchers suspect that factors other than fitness may influence men’s cancer risk.
For example, men who are more fit, researchers say, are also more likely to be recommended for prostate screenings and therefore more likely to have cancers found.
“It was still important for the patients who developed prostate cancer, it just didn’t protect them from developing the prostate cancer itself,” Dr. Lakoski says. “We need further study to look at the association between fitness and prostate cancer stage.”
One takeaway from the research may be that doctors need to gather more data during yearly physicals.
“It’s an exciting finding, because fitness is a modifiable behaviour,” says Melinda Irwin, PhD, MPH, an epidemiologist at the Yale Cancer Centre, who was not involved with the study. “Will this paper lead to a fitness test being measured in annual exams, just like cholesterol is or blood pressure? I think it should be, because it can better tell you your risk for cardiovascular disease and/ or cancer and give the patient more information.”
It may also provide a fitness incentive.
“If [men] are of a low fitness level, that may give them motivation to start an exercise programme,” Dr. Irwin says.
Researchers adjusted for a number of factors in their analysis, including age, BMI, smoking, cholesterol level, and blood pressure. So one finding consistent from past research is that fit patients had health benefits even if their body weight falls outside of what is considered ideal BMI range.
“Fitness is associated with mortality even after adjusting for these other risk factors,” Irwin says. “It’s really the physical activity that a person does to become more fit.”
Despite a number of studies showing a link between fitness and cancer risks, it’s still unclear why such a connection might exist.
“It’s a young area of research so I think we need more research in terms of those mechanisms,” says Duck-Chul Lee, PhD, an assistant professor of kinesiology at Iowa State University.
Among the possibilities, he says, are more physically-fit individuals have more active immune systems and lower levels of chronic inflammation.
The next challenge for researchers is to see whether helping patients change their fitness levels has an impact in lowering their risks of contracting or dying from cancer.
“There are not many studies looking at the change in fitness specifically on cancer and mortality,” Dr. Lee says.
*Culled from Everyday health
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