Sitting Too Much May Raise Risk of Colon Cancer
Published: Oct 30, 2013 | Updated: Oct 31, 2013. By Michael Smith, North American Correspondent, MedPage Today, Reviewed by F. Perry Wilson, MD, MSCE; Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner.
Men who spend most of the day sitting might be increasing their chance of colorectal cancer, a researcher said.
In a pooled analysis of participants from two phase III clinical trials, men who were largely sedentary had an increased risk of recurring adenomatous polyps, according to Christine Sardo Molmenti, PhD, ofColumbia University Mailman School of Public Health in New York City.
On the other hand, there was no link between recurrence and sedentary behavior among women, Sardo Molmenti told reporters at the American Association for Cancer Research prevention conference in National Harbor, Md.
The clinical implication, she told MedPage Today, is that "clinicians should be encouraging patients to move, to stand, or really to do anything but stay in a sitting position for a large portion of time."
"There's a lot of value for these light, household activities, where you're not completely at rest, but you're not breaking a sweat to work out," she said.
The report comes the same week that European researchers also targeted sedentary behavior as a player in the development of metabolic syndrome and cardiovascular disease.
Doctors have tended to focus on the benefits of activity, rather than the risks of inactivity, commented Paul Limburg, MD, of the Mayo Clinic in Rochester, Minn., who was not part of the study but who moderated a press conference at which some details were presented.
The conversation has been "framed as physical activity is good, lower physical activity is not so good," he told MedPage Today. "But we haven't necessarily focused on the sedentary behavior component of it."
"There may be differences between physical activity and sedentary behavior, where those pieces of the conversation should be separate," he added.
Participants in the two studies -- the Wheat Bran Fiber and Ursodeoxycholic Acid clinical trials -- had one or more colorectal adenomas removed during a colonoscopy that took place within 6 months of enrolment.
Sardo Molmenti and colleagues analyzed adenoma recurrence for 1,730 participants who had available data from the baseline Arizona Activity Frequency Questionnaire and a follow-up colonoscopy during an average of 3 years of follow-up.
Using a logistic regression analysis, they looked at the relationship of activity -- sedentary, recreational, and household -- to colorectal adenoma recurrence, both overall and broken down by sex.
The investigators didn't find any statistically significant associations between activity types and adenoma recurrence overall, Sardo Molmenti said.
But when men were stratified into quartiles of sedentary time, those in the highest two groups -- 9 to 11 hours a day and 11 hours or more -- had about a 45% higher odds of adenoma recurrence.
Compared with the lowest quartile, the odds ratio for recurrence was 1.47 (95% CI 1.04-2.09) for those in the third quartile. And the odds ratio was 1.45 (95% CI 1.02-2.06) in the fourth quartile. The trend was significant at P=0.03, Sardo Molmenti reported.
The study was supported by the NIH and the National Cancer Institute. Sardo Molmenti declared no conflicts of interest.