Stop sitting down if you want to avoid cancer, warn researchers.
The risk of developing some cancers rises by up to 10 per cent for every extra two hours sitting, according to a new review of studies.
Worryingly, say scientists, the effect appeared to be unrelated to how much exercise people took when not sitting.
This suggests that even people who are generally physically active may increase their cancer risk by sitting down for too long.
Scientists came to the conclusion after studying pooled data from 43 studies with more than four million participants and almost 70,000 cancer cases.
There is growing evidence which suggests too much sitting – as opposed to insufficient activity – may be a new risk factor for premature death and illness such as diabetes and heart disease.
All the studies in the review involved questionnaires and interviews probing lifestyle habits related to activity such as TV viewing time, sitting time at home and at work, and total sitting time.
Comparing the highest and lowest levels of sedentary behaviour revealed a statistically significant increased risk for three specific cancers – bowel, endometrial (womb lining) and lung – associated with sitting.
Every extra two hours spent sitting was associated with a 10 per cent increased chance for women of developing cancer of the womb lining.
The risk of bowel and lung cancers was raised by eight per cent and six per cent respectively.
Study authors Daniela Schmid and Dr Michael Leitzmann, from the University of Regensburg in Germany, in a report in the Journal of the National Cancer Institute, say there are several possible biological reasons for the link between sedentary behaviour and cancer.
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