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new study finds that a pattern of lifelong
exercise reduces the risk of adenomatous polyps, which are a known precursor of
colorectal cancer.
New research suggests that exercise early in
life may preserve colorectal health later on.
It is not uncommon for a gastroenterologist
to discover one or more adenomatous polyps during a routine colonoscopy. While
these polyps are not cancerous, doctors consider them to be cancer precursors.
Although about half of people aged 60 years or older have them, just 6%
of the polyps become cancerous, and surgical removal prevents this from
happening.
Nonetheless, most colon and rectal cancers do
begin with polyps, so their presence can be worrying. However, there may be
ways to prevent colorectal polyps.
A new study that featured recently in
the British Journal of Cancer links
a lifetime of exercise with a significantly reduced risk of developing polyps.
"The links between physical activity,
adenomas, and colorectal
cancer are well understood," says Leandro Rezende, one of
the study's authors, "but this is the first study to demonstrate the
cumulative effects of physical activity starting in adolescence on the
incidence of colorectal adenoma."
The link between exercise and
adenomas
The study comes from researchers at the
University of São Paulo's Medical School (FM-USP) in Brazil, who collaborated
with colleagues from Harvard University in Cambridge, MA, and other medical
facilities in the northeast United States.
The authors' conclusions rely on the analysis
of data that they collected from 28,250 U.S. nurses who participated in
the Nurses' Health Study II.
Starting in the late 1980s and continuing
until 2011, the nurses provided information every 2 years about their health,
detailing any illnesses and habits such as smoking, as well as their hormone
use, pregnancies, and menopausal status.
In 1997, the researchers added questions that
asked the subjects about their lives from the ages of 12 to 21 years.
According to Rezende: "They answered
questions on home-school commute times and methods and on moderate physical
activity, such as walking, as well as more intense exercise, such as gym
classes, swimming, and other sports. This enabled us to estimate the level of
physical activity during their adolescence."
By the time the survey ended in 2011, the
nurses were also answering lifestyle questions that allowed the researchers to
collect information on how active or inactive they were as adults.
What the study found
The Nurses' Health Study II required all of
the participants to undergo at least one sigmoidoscopy or colonoscopy so that
the researchers could track occurrences of adenomatous polyps.
After adjusting for other cancer risk
factors, such as smoking, poor diet, alcohol, and family history, the authors
of the new study were able to see a few clear associations:
·
People
who had been active between the ages of 12 and 22 years were 7% less likely to
develop adenomatous polyps compared with those who did less than 60 minutes of
moderate exercise each day.
·
For
participants who were active only during adulthood — between the ages of 23 and
64 years — there was a 9% reduction in risk.
·
People
who were active both when young and during adulthood had a 24% reduction in
their likelihood of developing any adenomatous polyps.
"The reduction
is actually similar in each case," says Rezende, which suggests that
"there is a cumulative effect of physical activity as life goes on."
"Whether
it's during adolescence or adulthood, the more physical activity we get, the
lower the risk of developing adenoma in adulthood becomes."
Leandro Rezende
Finally, the researchers were also able to
draw a surprising conclusion regarding the development of larger, advanced
polyps specifically: Being active in both adolescence and adulthood reduced the
occurrence of these polyps by 39%.
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