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.
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.
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.
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.
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.