If more people knew about other kinds
of colorectal cancer testing, some experts hope, perhaps some who put off
colonoscopies would be screened and deaths from colon cancer could be avoided,
colonoscopyIf more people knew about other kinds of colorectal cancer testing,
some experts hope, perhaps some who put off colonoscopies would be screened and
deaths from colon cancer could be avoided.
This year about 53,000 Americans are
expected to die from colon or rectal cancer. Doctors say most people should
start getting screened at age 45. Yet many who are eligible skip testing.
When most people in this country
think of colon cancer screening, they think of colonoscopies, which let doctors
examine the colon but can be inconvenient. Yet there are other equally
acceptable options for screening.
If more people knew about other kinds
of colorectal cancer testing, some experts hope, perhaps some who put off
colonoscopies would be screened and deaths from colon cancer could be avoided.
Here’s what you need to know about
colonoscopies and fecal tests, which to ask for, and why your doctor might be
recommending one over the other.
How do colonoscopies and fecal tests
work?
Colonoscopies are widely used, but
there is another option available: fecal tests.
Both types of test attempt to find
cancers and large polyps — growths on the wall of the colon — that occasionally
turn into cancers. Cancers that are found early often can be cured when doctors
simply cut them out. Finding and removing polyps can also prevent cancers.
Colonoscopies start with a patient’s
taking strong laxatives to empty the colon. On the day of the test, the patient
is sedated. Then, a doctor inserts a colonoscope — a flexible tube with a video
camera at the end — into the rectum and colon and looks for polyps and cancers
to remove. The doctor may also take samples for study in a lab.
If no polyps or cancers are found,
the average patient can wait 10 years before having another colonoscopy.
Fecal tests can be done at home.
Patients collect a stool sample and mail it to or drop it off at a testing lab.
One option is the fecal
immunochemical test, or FIT, which should be repeated annually. A lab analyzes
the sample for traces of blood, which can indicate a polyp or cancer. Large
polyps and colon cancers sporadically ooze small amounts of blood. If blood is
detected, the patient must have a colonoscopy.
Another more complex fecal test is
Cologuard, repeated every three years. It looks for blood in stool and also for
abnormal DNA from large polyps and colon cancers. Like the FIT test, Cologuard
must be followed by a colonoscopy if blood or abnormal DNA are present.
If a person who has a large polyp has
a colonoscopy, the test will detect it 95% of the time. If that person has a
Cologuard test, there is a 42% chance that it will be positive because of the
polyp. If the person has a FIT test, there is about a 22% chance it will be
positive.
Colonoscopies find 95%. A one-time
Cologuard test will be positive 94% of the time if a cancer is present, and a
FIT test will be positive 74% of the time.
The ultimate goal, though, is
preventing colon cancer deaths. For now, no one really knows which test
performs better. One large clinical trial by the Department of Veterans Affairs
is comparing the number of colon cancer deaths among 50,000 patients randomly
assigned to have a colonoscopy or an annual FIT test and followed for 10 years.
Results are expected in 2027 or 2028.
While those studies are continuing,
other studies have compared a screening test with no test.
One study found that after 30 years,
people who had fecal tests had a 33% lower death rate from colon cancer than
people who were not screened. The death rate fell to 2%, from 3%.
A 10-year European study of
colonoscopy found a 30% reduction in the risk of getting colon cancer. It was
0.84% in a group that had colonoscopies and 1.22% in a group that was not
screened. There was no difference in the risk of dying from colon cancer.
Whether the reduction in the risk of
getting colon cancer is worth a potential risk of injury during the surgery is
“in the eye of the beholder,” said Dr. Michael Bretthauer, a gastroenterologist
at the University of Oslo who led the study.
The ultimate goal, though, is
preventing colon cancer deaths. The ultimate goal, though, is preventing colon
cancer deaths. (Source: Freepik)
Can I ask my doctor for a fecal test
if I prefer it to a colonoscopy?
Of course — if you are of average
risk, meaning no family history of colon cancer and no genetic condition that
predisposes to colon cancer. If you are at a higher risk, your doctor is likely
to advise a colonoscopy.
When patients of average risk ask Dr.
David Lieberman, a gastroenterologist at Oregon Health and Science University,
if they can skip the colonoscopy, he explains that a fecal test and a
colonoscopy accomplish different things. Fecal tests are likely to find cancers
when they are early enough to be cured. But he says those tests are not so good
at finding precancerous polyps. While the hope is that, repeated over time, the
fecal tests will find polyps, colonoscopies find both with a single test.
Hearing that, he said, most patients
decide they want colonoscopies.
What do the tests cost?
Many patients pay little or nothing
because insurance, including Medicare, covers the tests. But testing does cost
the health care system.
Prices for the testing vary, but one
estimate says a colonoscopy for people with private insurance costs the insurer
about $3,442. A single Cologuard test costs about $763, and a single FIT test
costs about $91.
Why do doctors prefer colonoscopies?
Many doctors think they are saving
patients’ lives with colonoscopies.
“The idea of finding and removing
cancer precursor lesions became very attractive to physicians,” Lieberman said.
But there is also a financial
incentive for the procedure.
“Colonoscopy is a massive revenue
generator for hospital systems,” said Dr. Adewole Adamson, of the University of
Texas at Austin, who studies cancer screening.
Doctors profit too, said Dr. Samir
Gupta, a gastroenterologist at the University of California, San Diego. “When
we do the procedure, that’s part of our income,” he said. “We are all
conflicted.”
Many other countries with modern
national health systems use FIT tests because they are cheap, and because they
lack the capacity for wider use of colonoscopies.
But there are places in the U.S. that
don’t emphasize colonoscopies. Most VA centers mail FIT tests to eligible
patients every year.
So does Kaiser Permanente, one of the
nation’s largest medical care providers. In the company’s lab in Northern
California, for instance, testing is done “on an industrial scale,” said Dr.
Theodore Levin, a Kaiser gastroenterologist, with 15,000 to 20,000 FIT tests
processed each week.
In describing some of Kaiser’s
motivation for offering FIT, Levin added, “All the physicians are salaried, so
they are not doing screening to support their practice.”
Dr. Amitpal S. Johal, director of
gastroenterology at Geisinger, a large health care system in Pennsylvania, says
Cologuard is preferred because of its greater accuracy and because it only
needs to be done every three years. The test is useful for the system’s large
rural population for whom a center that does colonoscopies can be far away.
“Some of these people can’t drive
five hours” for the test, he said, while “Cologuard will mail the test to them,
and UPS will pick it up.”
When can I get a blood test instead
of these options?
The Food and Drug Administration
recently approved a blood test called Shield by the company Guardant Health.
The test looks for fragments of DNA shed from colon cancers and polyps. If it
finds evidence of cancer or large polyps, you need a colonoscopy.
The problem is that the test is not
very accurate and does especially poorly at finding large polyps. Still,
gastroenterologists say it is better than nothing.
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