Contact: gwen Ericson
Washington University School of Medicine
People who exercise lower their risk of colon cancer
An ambitious new study has added
considerable weight to the claim that exercise can lower the risk for
colon cancer. Researchers at Washington University School of Medicine
in St. Louis and Harvard University combined and analyzed several
decades worth of data from past studies on how exercise affects colon
cancer risk. They found that people who exercised the most were 24
percent less likely to develop the disease than those who exercised the
"What's really compelling is that we see the association
between exercise and lower colon cancer risk regardless of how physical
activity was measured in the studies," says lead study author Kathleen
Y. Wolin, Sc.D., a cancer prevention and control expert with the
Siteman Cancer Center at Barnes-Jewish Hospital and Washington
University. "That indicates that this is a robust association and gives
all the more evidence that physical activity is truly protective
against colon cancer."
Colorectal cancer is the third most common type of cancer. Each
year more than 100,000 people in the United States are diagnosed with
colon cancer and about 40,000 are diagnosed with rectal cancer. The
study suggests that if the American population became significantly
more physically active, up to 24 percent, or more than 24,000, fewer
cases of colon cancer would occur each year.
Wolin's report was published Feb. 10, 2009 through advance online publication in the
British Journal of Cancer.
In the study, she and her colleagues gathered the results from all
relevant studies published in English on the effect of physical
activity on colon cancer risk.
They eliminated from consideration any studies that combined
both colon and rectal cancer because exercise has not been shown to
affect rectal cancer risk — including such studies would have led to an
underestimation of the effect of exercise on colon cancer risk. In all,
they analyzed 52 studies going back as far as 1984, making their
analysis the most comprehensive to date.
They found that the protective effect of exercise held for all
types of physical activity, whether that activity was recreational,
such as jogging, biking or swimming, or job related, such as walking,
lifting or digging.
"The beneficial effect of exercise holds across all sorts of
activities," says Wolin, also assistant professor of surgery. "And it
holds for both men and women. There is an ever-growing body of evidence
that the behavior choices we make affect our cancer risk. Physical
activity is at the top of the list of ways that you can reduce your
risk of colon cancer."
The difference between people who were the most physically
active and those who were the least varied from study to study in
Wolin's analysis. As an example, in a 2007 study by Wolin and
colleagues, women who walked the most realized a 23 percent reduction
in their risk of colon cancer. Those highly active women walked briskly
for five to six hours each week. By comparison, the women in that study
who walked the least walked only a half hour each week.
Wolin KY, Yan Y, Colditz GA, Lee I-M. Physical activity and colon cancer prevention: a meta-analysis.
British Journal of Cancer. Feb. 10, 2009 (advance online publication).
University School of Medicine's 2,100 employed and volunteer faculty
physicians also are the medical staff of Barnes-Jewish and St. Louis
Children's hospitals. The School of Medicine is one of the leading
medical research, teaching and patient care institutions in the nation,
currently ranked third in the nation by U.S. News & World Report.
Through its affiliations with Barnes-Jewish and St. Louis Children's
hospitals, the School of Medicine is linked to BJC HealthCare.
Cancer Center is the only federally designated Comprehensive Cancer
Center within a 240-mile radius of St. Louis. Siteman Cancer Center is
composed of the combined cancer research and treatment programs of
Barnes-Jewish Hospital and Washington University School of Medicine.
Siteman has satellite locations in West County and St. Peters, in
addition to its full-service facility at Washington University Medical
Center on South Kingshighway.