Abstract
BackgroundThe literature suggests an increased risk between anthropometrics including higher body mass index and lymphoma incidence; however, the association with physical activity remains unclear. A systematic review/meta-analysis was therefore performed to examine this association with physical activity (total, recreational or occupational).MethodsPubMed, Web of Science and Embase were reviewed from inception to October 2019 identifying relevant observational studies. Non-Hodgkin lymphoma (NHL) including subtypes diffuse large B cell lymphoma, follicular lymphoma and chronic lymphocytic leukemia/small lymphocytic lymphoma, and Hodgkin lymphoma (HL) were analyzed. Included studies reported activity, lymphoma cases, effect size and variability measures, and were restricted to human subjects of any age. Data was pooled generating summary relative risk (RR) estimates with 95% confidence intervals (CI) using random-effects models with primary outcome of histologically confirmed incident lymphoma.ResultsOne thousand four hundred studies were initially identified with 18 studies (nine cohort, nine case-control) included in final analysis. Comparing highest vs. lowest activity categories was protective for all lymphoma (RR 0.89, 95%CI 0.81–0.98). Sensitivity analysis demonstrated effect persistence within case-control studies (RR 0.82, 95% CI 0.71–0.96), but not cohort studies (RR 0.95, 95%CI 0.84–1.07). Borderline protective effect was seen for NHL (RR 0.92, 95%CI 0.84–1.00), but not HL (RR 0.72, 95%CI 0.50–1.04). Analysis by NHL subtype or gender showed no effect. Dose response analysis demonstrated a protective effect (p = 0.034) with a 1% risk reduction per 3 MET hours/week (RR 0.99, 95%CI 0.98–1.00).ConclusionsPhysical activity may have a protective effect against lymphoma development; further studies are required to generate recommendations regarding health policy.Trial registrationThis study was registered prospectively at PROSPERO: CRD42020156242.
Highlights
The literature suggests an increased risk between anthropometrics including higher body mass index and lymphoma incidence; the association with physical activity remains unclear
Prior metaanalyses demonstrated a relationship between obesity and lymphoma incidence in a dose-dependent manner [5,6,7]; it remains unclear if there is an association between physical activity and lymphoma independent of body mass index (BMI) [8]
The PRISMA flowchart detailing study review is presented in Fig. 1; the most common reasons for exclusion were lack of physical activity information (n = 33), review or commentary (n = 16), not relevant (n = 12, ie. physical activity levels after diagnosis of lymphoma), duplicate (n = 11), meta-analyses (n = 8), etc
Summary
The literature suggests an increased risk between anthropometrics including higher body mass index and lymphoma incidence; the association with physical activity remains unclear. Hodgkin lymphoma (HL) is much less common with only 8110 new cases and 1000 deaths per year The incidence for both types has been decreasing over the past decade, with a drop of 0.9 and 1.8% yearly for NHL and HL respectively [3]. Prior metaanalyses demonstrated a relationship between obesity and lymphoma incidence in a dose-dependent manner (obesity vs overweight vs normal weight) [5,6,7]; it remains unclear if there is an association between physical activity and lymphoma independent of body mass index (BMI) [8]. Better understanding of the available evidence for lymphoma could inform discussions with patients and better guide health policy recommendations
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