A sedentary lifestyle, long believed to contribute to chronic conditions such as heart disease, can increase the risk of colon cancer, according to a study in the American Journal of Epidemiology.
Activities are considered sedentary if they require very low energy expenditure, such as prolonged sitting. Previous studies have associated sedentary work with a higher risk for colorectal cancer but most have focused on one occupation at a single point in time.
In this study, Australian scientists collected data from 2005 to 2007 on employment history, lifestyle and physical activity from 918 colon-cancer patients and 1,021 controls. Jobs were ranked according to the level of physical activity, from light to very heavy. Subjects who spent 10 or more years in sedentary jobs had twice the risk of colon cancer and a 44 percent increased risk of rectal cancer, compared with those who never held a sedentary job. The association was independent of recreational physical activity. Occupations requiring heavy physical activity were associated with a 44 percent reduced risk of colon cancer compared with light-activity work.
The findings have occupational health implications, researchers said.
People in sedentary jobs for 10 years or more had twice the colon-cancer risk of those without such jobs.
Caveat: Sedentary work was associated with cancers of the rectum and distal colon but not the proximal colon.