Colonoscopy Test for Colon Cancer May Be More Effective
June 14, 2000 -- Even among people who've never had one, the term barium
enema can inspire fear. Long used to screen for colon cancer, barium enemas
have recently fallen out of favor with those who prefer an imaging method
called colonoscopy. And a new study shows that, in people with a history of
colon growths, or polyps, colonoscopies may be better than barium enemas at
The research comes amid continuing debate about which technique is better
for follow-ups after the recommended colon cancer screening performed in all
people over age 50. Although this study, published in the New England
Journal of Medicine, does not address whether colonoscopies also should be
used for the initial screening, some experts, including the study's author,
tell WebMD that it should.
Sidney J. Winawer, a gastroenterologist at Memorial Sloan-Kettering Cancer
Center in New York, tells WebMD that barium enemas are no longer practical. But
"colonoscopy for cancer screening presents a unique activity -- we can find
polyps and remove them, and actually prevent cancer."
Both barium enemas and colonoscopy involve making images of the colon, and
both have the same goal -- finding polyps, some of which may become cancerous
over time. With both procedures, patients must eat a special diet or drink
liquids to empty the bowel the day before to make the tests more accurate.
In a colonoscopy, a specialist uses a small tube to introduce air into the
bowel in order to see the polyps. Its advantage is that physicians can remove
the polyp as soon as it is discovered. But there is a small risk of tearing the
bowel during the procedure, and the patient must be sedated, which can cause
side effects. This procedure also is more costly than a barium enema.
A few months ago, broadcast journalist Katie Couric underwent a colonoscopy
on television to call attention to colon cancer, which killed her husband.
In barium enemas, a radiologist introduces the element barium into the
bowel, along with air. No sedation is required. If polyps that should be
removed are detected during a barium enema, a colonoscopy usually is
Although there is no dispute that people over age 50 should be screened for
colon cancer, the medical community has been split over which methods are best.
In addition to barium enemas and colonoscopies, other recommended screening
tests for colon cancer include a fecal occult test, which can detect blood in
the stool, and sigmoidoscopy, which is less invasive than a colonoscopy.
The study by Winawer and his colleagues is the first to match one method
against the other to see which is better at detecting polyps. The researchers
performed both barium enemas and colonoscopies on more than 500 people, and
also reviewed the findings on more than 300 other people who had only
colonoscopies. All the patients previously had polyps. Colonoscopies found
three times as many smaller polyps and twice as many larger ones as barium