July 18, 2012 | 3 minute read

Worldwide, one in ten cases of both breast cancers and colon cancers is due to a lack of physical activity, with inactivity as much to blame for the major chronic diseases as smoking or obesity, finds a major new report published today in The Lancet.

The study’s cancer preventability figures expand the estimates released at last year’s AICR Research Conference, which linked inactivity in the United States to three of every ten colon cancers and two of every ten breast cancer cases.

In this study, researchers quantified for the first time the global impact of physical inactivity, suggesting that inactivity is responsible for almost 9 percent of all deaths worldwide.

The findings are one in a series of six (free) papers published today in The Lancet.

In the Lancet study, researchers estimated how many of the three major non-communicable diseases  — heart disease, diabetes, and cancers – could be prevented if inactive people were to become active. They focused on breast and colon cancers, given the strong evidence relating the two cancers to physical inactivity.

For the calculations, researchers first gathered data on the percentages of inactive people in countries throughout the world, including countries in Africa, Asia, Latin America, Europe and the Western Pacific. Inactivity was defined as any level below the World Health Organization activity recommendations, which are similar to US government recommendations: Adults should get at least 150 minutes of moderate-intensity aerobic activity each week, with muscle strengthening activities at least two days a week.

Researchers then used the most recent analyses of the evidence looking at how physical inactivity links to the risk of each disease.

The study determined that physical inactivity causes 6 percent of coronary heart disease; 7 percent of type 2 diabetes; 10 percent of breast cancers, and 10 percent of colon cancers. Together, inactivity caused more than 5.3 million of the 57 million deaths that occurred worldwide in 2008.

The authors concluded that if the population as a whole were only 10 percent more active, they would prevent more than 533,000 deaths every year; if the population was 25 percent more active, the world could prevent more than 1.3 million deaths each year.

AICR’s expert report and its updates link physical activity to decreased risk of colorectal, postmenopausal breast and endometrial cancers. The reports, a review of the global research, also found that watching too much television and being sedentary increases the risk of weight gain and obesity, which is linked to increased risk of seven types of cancer.