Abstract
Prostate cancer is the second most common cancer in men worldwide, and sedentary behavior is widespread, yet reviews and meta-analyses summarizing the role of sedentary behavior as a potential risk factor for prostate cancer are scarce. We searched PubMed, Web of Science, and Cochrane databases for relevant articles up to January 2019. We pooled maximally adjusted risk estimates in a random effects model and performed meta-regression meta-analysis, assessed heterogeneity and publication bias using I², funnel plots, and Egger and Begg tests, and conducted sensitivity analyses and influence diagnostics. Data from 12 prospective cohort studies including a total of 30,810 prostate cancer cases were analyzed. We found no statistically significant association between high versus low sedentary behavior and prostate cancer incidence [RR = 1.07; 95% confidence interval (CI), 0.99-1.16; P = 0.10]. We noted that adjustment for body mass index (BMI) modified the relation of sedentary behavior to prostate cancer, particularly aggressive cancer. Sedentary behavior was related to a statistically significant increased risk of aggressive prostate cancer in analyses not adjusted for BMI (RR = 1.21; 95% CI, 1.03-1.43), whereas no association was apparent in BMI-adjusted analyses (RR = 0.98; 95% CI, 0.90-1.07), and the difference between those summary risk estimates was statistically significant (P difference = 0.02). Sedentary behavior is not independently associated with prostate cancer. However, prolonged sedentary behavior may be related to increased risk of aggressive prostate cancer through a mechanism involving obesity. This finding represents a potentially important step toward considering sedentary behavior as a modifiable behavioral risk factor for aggressive prostate cancer.
Highlights
Sedentary behavior is widespread, with objectively assessed measures indicating that adults spend more than half their waking day in sedentary pursuits [1]
We considered a subgroup of aggressive prostate cancer and found a null relation with sedentary behavior (RR 1⁄4 1.05; 95% confidence interval (CI), 0.95–1.15), with low heterogeneity between studies (I2 1⁄4 21.7%; Pheterogeneity 1⁄4 0.39; Fig. 3)
Our primary finding is that sedentary behavior shows no statistically significant association with prostate cancer
Summary
With objectively assessed measures indicating that adults spend more than half their waking day in sedentary pursuits [1]. Established risk factors include age, family history of prostate cancer, and African-American ethnicity [4, 5]. There is increasing evidence that greater body fatness is related to risk of advanced prostate cancer, and research into additional modifiable risk factors such as diet and physical activity has gathered particular attention throughout the past years [5]. Among these lifestyle factors, sedentary behavior has recently emerged as a potential determinant of prostate cancer risk. Sedentary behavior is defined as "any waking behavior characterized by an energy expenditure 1.5 metabolic equivalents, while in a sitting, reclining, or lying posture" [7]
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