Prior studies have shown the benefits of physical activity in reducing the risk of colon and breast cancers, and now new data appear to show a similar risk reduction for non-Hodgkin lymphoma (NHL).
In the study, now online ahead of print in the AACR journal Cancer Epidemiology, Biomarkers & Prevention (doi: 10.1158/1055-9965.EPI-14-1303), Terry Boyle, PhD, a postdoctoral fellow in the Department of Cancer Control Research at the BC Cancer Agency and the School of Population and Public Health at the University of British Columbia, and colleagues note that because not much is known about what causes NHL, it is particularly important to identify risk factors.
The team used data from a case-control study conducted between 2000 and 2004 in British Columbia, which included 820 NHL patients (59% of whom were men) of various ages from the BC Cancer Registry and 848 randomly selected controls matched for age, gender, and residential location, from the Client Registry of the British Columbia Ministry of Health.
Information on demographics and various risk factors for NHL, including lifetime recreational physical activity, was collected using 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 assigned a metabolic-equivalent (MET) value to the different types of physical activity, and calculated the average number of MET-hours per week of physical activity for each participant's lifetime, taking into account both the duration and intensity of physical activity.
Study participants who were in the higher (second, third, and fourth) quartiles of vigorously intense physical activity performance in their lifetimes had a reduced risk for NHL of about 25 to 30 percent compared with those lowest (first) quartile of vigorously intense physical activity. Physical activity was not associated with greater benefit for any specific age group.
“In this case-control study, we found that the most physically active participants had a lower risk for NHL than the least active participants,” Boyle said in a news release. “We found that vigorous-intensity physical activity in particular, such as activities that increase breathing and heart rates to a high level, was the most effective at lowering risk.
“Currently, there isn't enough research on this topic to be able to confidently say that being physically active reduces the risk of non-Hodgkin lymphoma, so we are planning to pool data from several studies to investigate this topic further. 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.”
The study was funded by the Canadian Cancer Society and the Canadian Institutes of Health Research.