(HealthDay News) — Prolonged television (TV) viewing and other sedentary behaviors are associated with increased risks of some cancers, according to research published online in the Journal of the National Cancer Institute.

Daniela Schmid, PhD, and Michael F. Leitzmann, MD, DrPH, of the University of Regensburg in Germany, performed a meta-analysis using data from 43 observational studies involving 68,936 cancer cases. The researchers sought to assess the association between sedentary behaviors and cancer risk.

For the highest versus the lowest levels of sedentary time, the researchers observed increased relative risks (RRs) for colon cancer associated with TV viewing time (RR, 1.54; 95% confidence interval [CI], 1.19 to 1.98), occupational sitting time (RR, 1.24; 95% CI, 1.09 to 1.41), and total sitting time (RR, 1.24; 95% CI, 1.03 to 1.50). 

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For endometrial cancer, increased relative risks were associated with TV viewing time (RR, 1.66; 95% CI, 1.21 to 2.28) and total sitting time (RR, 1.32; 95% CI, 1.08 to 1.61). 

Overall sedentary behavior was positively associated with increased risk of lung cancer (RR, 1.21; 95% CI, 1.03 to 1.43). 

No association was found between sedentary behavior and risk of cancers of the breast, esophagus, non-Hodgkin lymphoma, ovaries, prostate, rectum, renal cell, stomach, or testes.

“Prolonged TV viewing and time spent in other sedentary pursuits is associated with increased risks of certain types of cancer,” the researchers wrote.

In a related editorial, Lin Yang and Graham A. Colditz, MD, DrPH, commented on the findings.

“Reductions in sedentary behavior are recommended for cancer reduction and improvement in overall mortality. Strategies remain poorly defined to meet this goal independent of weight control. Priority should be placed on refining interventions, independent of physical activity and obesity prevention, to reduce sedentary time and lower cancer risk and overall mortality,” they wrote.

“These will then be integrated into a broader framework for an effective strategy to implement and monitor them to reduce the cancer burden as society continues to remove activity from how we structure our civilization.”


  1. Schmid D, Leitzmann MF. Television Viewing and Time Spent Sedentary in Relation to Cancer Risk: A Meta-analysis. J Natl Cancer Inst. 2014;doi:10.1093/jnci/dju098.
  2. Yang L, Colditz GA. An Active Lifestyle for Cancer Prevention. J Natl Cancer Inst. 2014;doi:10.1093/jnci/dju135.