Removing Colon Polyps Cuts Death Risk
First Colonoscopy to Clear Colon of Precancerous Polyps Cuts Colon Cancer Death Risk by 90%
WebMD News Archive
Oct. 15, 2007 (Philadelphia) -- An initial colonoscopy during which the
colon is cleared of precancerous polyps significantly reduces deaths from colon
cancer -- even if there are no follow-up exams, researchers report.
In a 20-year study of more than 2,500 people, the risk of dying from
colon cancer was about 90% lower if people underwent both the initial and
follow-up procedures than if they underwent neither.
But over the first 10 years, 90% of that effect was due to the initial exam,
says Ann G. Zauber, PhD, a biostatistician at Memorial Sloan-Kettering Cancer
Center in New York.
Over the next 10 years, 55% of the effect was still due to the initial
“Removing [potentially precancerous growths] has a huge effect on reducing
colon cancer mortality,” Zauber tells WebMD.
“The surveillance colonoscopies had more of an effect in the second decade
than in the first, but the initial procedure still is the major effect,” she
The findings were presented at the annual meeting of the American College of
Colonoscopy Plus Polyp Removal Cuts Colon Cancer Deaths
The researchers analyzed data on 2,602 men and women in the National Polyp
Study, the landmark trial that showed that an initial colonoscopy during which
the colon is cleared of precancerous polyps with regular follow-up exams
significantly cut the risk of developing colon cancer by up 90% and of dying
from the cancer by up to 92%.
Using sophisticated mathematical modeling, they found that:
- Failing to do a colonoscopy and remove precancerous polyps is associated
with a 5.5% risk of death over 20 years.
- Doing only an initial exam with removal of precancerous polyps is
associated with a 2.5% risk of death over 20 years.
- Doing both an initial exam to remove precancerous polyps and follow-up
exams is associated with less than a 1% risk of death over 20 years.
ACG President David A. Johnson, MD, a gastroenterologist at Eastern Virginia
Medical School in Norfolk, tells WebMD that the findings could influence
guidelines, lengthening the time between exams for people who have had polyps
removed to six years or more. Recommendations now call for a follow-up
colonoscopy in three to five years.
“Once you clear the colon, maybe you can wait a longer time depending on
risk. That first removal of polyps is the time when you make the biggest impact
on risk for colon cancer incidence and colon cancer death,” Johnson says.