Photo by Shannon E. Renfroe
People who regularly engage in vigorous physical activity throughout their lifetime may have a lower risk of developing non-Hodgkin lymphoma (NHL), according to research published in Cancer Epidemiology, Biomarkers & Prevention.
“We know that being physically active reduces the risk of colon cancer and breast cancer, and also leads to a range of other physical and mental health benefits,” said study author Terry Boyle, PhD, of the University of British Columbia in Vancouver, Canada.
“Our findings suggest that people who do vigorous physical activity may also have a lower risk for NHL.”
Dr Boyle and his colleagues used data from a case-control study conducted between 2000 and 2004 in British Columbia. The team analyzed 749 NHL patients and 818 control subjects matched for age, gender, and residential location.
Study subjects recorded information on demographics and various risk factors for NHL, including lifetime recreational physical activity, on a questionnaire. Participants were asked to record the average number of days per week and average number of hours per day they performed mild, moderate, or vigorous physical activity for each decade of life.
The researchers defined “mild” activities as those that increase heart and breathing rates above resting level, “moderate” activities as those that increase heart rate moderately, and “vigorous” activities as those that increase breathing and heart rates to a high level. Mild and moderate activity were ultimately combined into a single category.
The team assigned a metabolic-equivalent (MET) value to the different types of physical activity.
Then, to assess the association between lifetime physical activity and NHL risk, the researchers calculated the average MET-hours per week over a lifetime for total physical activity, moderate-intensity activity, and vigorous-intensity activity. Finally, they classified participants into quartiles.
Participants who engaged in the most vigorously intense physical activity throughout their lifetime were classified in the second, third, and fourth quartiles. These subjects had about a 25% to 30% lower risk for NHL when compared to participants in the lowest (first) quartile of vigorously intense physical activity.
The adjusted odds ratio was 0.69 for the second quartile, 0.68 for the third, and 0.75 for the fourth (PTrend=0.072).
There was an inverse association between lifetime vigorous-intensity physical activity and overall NHL risk in males and females, as well as for all NHL subtypes. Furthermore, vigorous physical activity did not confer a greater benefit for any specific age group.
The researchers found no association between total lifetime physical activity and NHL risk or lifetime moderate-intensity physical activity and NHL risk.
Despite these results, Dr Boyle said there isn’t enough research on this topic to confirm that being physically active reduces the risk of NHL.
“So we are planning to pool data from several studies to investigate this topic further,” he said. “We know that different types of NHL may have different risk factors, so we are also planning to investigate whether physical activity influences the risk for different types of NHL in different ways.”
