In a prospective study of multiple ethnic groups, people with at least 1 hour of moderate physical activity per week had a one-third lower risk of colon polyps.
"One thing that was new and exciting about our research was that the ethnic diversity in our population was different" from that of other studies, Dr. Nelson Sanchez of Memorial Sloan-Kettering Cancer Center, New York, said during a press conference in advance of the annual Digestive Disease Week. The findings were presented at the meeting on May 8.
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Prevalence of colon polyps was significantly higher among patients who reported less than 1 hour per week of exercise, compared with those who reported exercising for 1 hour or more (33.2% vs. 25.3%).
Of the 982 middle-aged adults who enrolled in the study, 558 (57%) were Hispanic, 202 (21%) were Asian, 149 (15%) were black, and 69 (7%) were white. A total of 603 participants (61%) had a body mass index that was categorized as overweight or obese (25 kg/m2 or greater).
The participants all had average risk for colorectal cancer, and the polyps were identified during screening colonoscopy. The overall prevalence of colon polyps was 29.5%, but the prevalence was significantly higher among patients who reported less than 1 hour per week of exercise, compared with those who reported exercising for 1 hour or more (33.2% vs. 25.3%, respectively); this difference was statistically significant (P = .008).
About half of the participants (513 individuals, or 52%) reported that they exercise for at least 1 hour per week, and the median duration of this activity level was 5 years (range, 1.5-10 years).
In addition, the researchers looked at risk for adenomas, which can be precursors of colorectal cancer, particularly if they are advanced adenomas. Those participants who exercised for 1 or more hours weekly had an adenoma prevalence of 14%, compared with 19% in those who exercised less than 1 hour a week, said Dr. Sanchez.
Also, overweight and obese patients who exercised at least 1 hour per week were 40% less likely to have any adenomas, and 63% less likely to have advanced adenomas than were overweight or obese individuals who exercised less, the researchers noted.
When the data were analyzed by race/ethnicity, the odds of having advanced adenomas greater than 1 cm in size or having colorectal cancers were lowest for blacks who exercised for at least 1 hour each week (odds ratio, 0.16). In addition, the odds ratio for adenomas was cut in half (0.47) for Hispanics who exercised for at least 1 hour each week, compared with Hispanics who exercised less.
These results could have a substantial public health impact, as they suggest that even a moderate level of exercise may reduce polyp risk in a diverse population, said Dr. Sanchez. "Even low levels of physical activity have been shown to confer protective benefits," he noted.
The next steps for researchers include identifying which specific physical activities and what level of intensity convey the most protection from colon polyps, Dr. Sanchez added.
Dr. Sanchez said he had no financial conflicts to disclose.