Background:
Sedentary behavior has been suggested to represent a risk factor for chronic morbidity and mortality. The relation of television (TV) viewing to cancer risk has not been quantitatively summarized using meta-analysis.
Aim:
We aimed to quantify the relations of TV viewing time, recreational sitting time, occupational sitting time, and total sitting time to the incidence of any type of cancer.
Methods:
We searched Cochrane, EMBASE, Medline, and SciSearch data-bases through February 2014 for published articles exploring TV viewing and other sedentary behaviors in relation to cancer incidence. The meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant studies were summarized using random-effects meta-analysis and meta-regression.
Results:
We included information from 43 observational studies and 68 936 cancer cases in our meta-analysis. High versus low levels of TV viewing time were related to a significant increased risk of colon cancer (Relative risk [RR]=1.54; 95% confidence interval [CI]=1.19 to 1.98) and endometrial cancer (RR=1.66; 95% CI=1.21 to 2.28). Further, increased occupational sitting time was associated with an elevated risk of colon cancer (RR=1.24; 95% CI=1.09 to 1.41). For total sitting time, the RRs were 1.24 (95% CI=1.03 to 1.50) for colon cancer, 1.32 (95% CI=1.08 to 1.61) for endometrial cancer, and 1.21 (95% CI=1.03 to 1.43) for lung cancer. By comparison, sedentary behavior was unrelated to cancers of the breast, rectum, ovaries, prostate, stomach, esophagus, testes, renal cell, and non-Hodgkin lymphoma.
Conclusions:
According to our meta-analysis of observational epidemiologic studies, prolonged TV viewing and time spent in other sedentary behaviors represents a risk factor for the development of certain types of cancer.