"An analysis with fewer studies suggests the effect was independent of how active participants were, suggesting that sedentary behavior represents a potential cancer risk factor distinct from physical inactivity.
When the highest levels of sedentary behavior were compared to the lowest, the study found a higher risk for colon, endometrial, and lung. For every two hours of sitting, the risk increased 8 percent for colon cancer and 10 percent for endometrial cancer. Long periods of watching TV showed the strongest relationship with increased risk of colon and endometrial cancers. This might be due to the link between watching TV and poor eating habits, notes Schmid."