From the Journals

Physical inactivity linked to lymphoma risk


 

FROM LEUKEMIA RESEARCH

A lifetime of physical inactivity could significantly increase the risk of developing both Hodgkin and non-Hodgkin lymphoma, according to a case-control study.

Researchers examined self-reported lifetime physical activity in 87 patients with Hodgkin lymphoma and 236 patients with non-Hodgkin lymphoma, as well as 1,300 cancer-free controls.

a closeup of feet running for exercise pojoslaw/ThinkStock
They found a significant positive association between physical inactivity – defined as less than one session of exercise per week across a lifetime – and both lymphomas. Participants who were classed as “physically inactive” had a significant 90% greater risk of Hodgkin lymphoma (P = .012) and a 35% greater risk of non-Hodgkin lymphoma (P = .046), after adjustment for age, sex, family history, body mass index, smoking, and education, John Lewis Etter and his colleagues from the Roswell Park Comprehensive Cancer Center in Buffalo, N.Y. reported in Leukemia Research.

Researchers also found a nearly threefold higher risk of Hodgkin lymphoma among overweight and obese individuals who were physically inactive, compared with those who were active (odds ratio, 2.79; P = .01). Similarly, physically inactive individuals who had never smoked had a greater than threefold increase in risk, compared with never-smokers who were active (OR, 3.30; P less than .001). But despite these significant associations for smoking and weight, the small samples sizes meant they were not significant in multivariable-adjusted models, the researchers noted. For non-Hodgkin lymphoma, the associations between obesity/overweight and smoking status were also not statistically significant in multivariable-adjusted models.

Previous studies looking at the role of physical activity in Hodgkin and non-Hodgkin lymphoma had yielded mixed and inconclusive results. Since then, researchers have begun to specifically consider the role of physical inactivity, rather than physical activity, as the exposure of interest.

“An additional advantage of identifying inactivity as the exposure of interest is that a body of literature suggests that those who are at the lower end of the physical activity continuum are less likely to overreport physical activity than those who engage in greater levels of physical activity,” the researchers wrote.

They acknowledged that relying on self-reported levels of physical activity was a limitation of their study. However, they also pointed out that previous research suggested that simplified physical activity questionnaires that took a dichotomous approach to activity/inactivity were effective at identifying the most physically inactivity individuals in a population.

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