Sitting, Cancer Risk, and Developing Strategies to do Something About It | Public Health Sciences Division

This post seems a bit cruel, coming out as it does during the current TV season’s finale week and the beginning of the World Cup. But, science doesn’t rest – not even for Game of Thrones or the Brazilian national soccer team. So, neither do we.

Just released on the Journal of the National Cancer Institute‘s website is a new analysis by two German researchers that combined the results from numerous studies on sedentary behavior and found that the simple act of sitting can significantly increase the risk of multiple cancers, including colon cancer, endometrial cancer, and lung cancer. Even in those who exercised regularly, being sedentary increased cancer risk.

The large analysis looked at data from 43 observational studies that included nearly 70,000 cancer cases. The researchers found that, compared to those who sat the least, those who sat the most had a 24 percent higher risk of colon cancer, a 32 percent higher risk of endometrial cancer, and a 21 percent higher risk of lung cancer. When looking only at TV viewing, the risks jumped considerably, with the risk of colon cancer increased by 54 percent and endometrial cancer by 66 percent.

Researchers hypothesized that time spent watching television was linked to greater risk than say, time spent sitting at work, because people who are watching TV are more likely to spend that time eating unhealthy foods, drinking alcohol, and smoking.

Although regular physical activity is a great boon to health, this new report also helped confirm that exercise is not enough on its own to protect against the health risks of an overall sedentary lifestyle. Even after taking activity level into account, high levels of sedentary behaviors still increased the risk of colon cancer by 20 percent and endometrial cancer by 32 percent (see figure).

In an accompanying editorial, Washington University School of Medicine researchers, Lin Yang and CNiC’s Graham Colditz, discuss how the continuing modernization of society sets the stage for increasingly sedentary lifestyles and the negative health effects that go with it. To successfully combat sedentary lifestyles it will take approaches similar to those that helped rein in tobacco use and that have just started to show some success against obesity. The key is targeting multiple layers of society, and with appropriate resources. These include worksite policies that can help reduce sitting time (such as, standing desks, regular standing/walking breaks, and active (vs. passive) commuting benefits) and programs focussed on youth that promote physical activities as an attractive choice to sedentary screen time.

With recent high profile studies, sitting is quickly being recognized as the health risk that it is. For many years, it was seen simply as the direct opposite of exercise and physical activity. And while there are clearly close links between the two, it’s now clear that it is an important cancer risk factor even in those who exercise regularly.

Because this relationship has taken a while to be broadly recognized, we’re behind in developing strategies to effectively address the issue. As Yang and Colditz state: “strategies remain poorly defined to meet this goal [of reductions in sedentary behavior].”

Now that we have the results of this latest analysis to further show the impact that sedentary lifestyles are having on our health, it’s time to develop an approach to address the issue with the energy and resources that are equal to its impact.

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