For people who have had a negative colonoscopy, less-invasive screening
options may work just fine for follow-up cancer tests, a new analysis suggests.
"No one screening test is right for everyone," lead researcher Amy
Knudsen, from the Institute for Technology Assessment at Massachusetts General
Hospital in Boston, told Reuters Health in an email.
The findings, which are based on a mathematical model, showed life
expectancy varied by only a few days between people who continued getting
colonoscopies every ten years and those who chose annual fecal blood tests and
other less-invasive alternatives. "The best test for you depends on your
risk, your preferences, and which screening approach you are willing and able
to adhere to, since no screening is effective unless it's done," she
added. "Patients should talk with their doctors to decide which test is
best for them."
Knudsen's team fed colon cancer screening and survival data into a
National Cancer Institute (NCI) model, starting with hypothetical study
participants that had a negative colonoscopy at age 50. The researchers found
that with no further screening, 31 out of every 1,000 people would be diagnosed
with colon cancer during their lives and 12 would die from it. For people who
continued having colonoscopies every ten years, that would fall to eight colon
cancer diagnoses and two deaths per 1,000 people.
With annual fecal tests starting at age 60, Knudsen and her colleagues
calculated that 11 to 13 out of every 1,000 people would get colon cancer, and
three or four would die. And with the last screening method, known as computed
tomographic colonography, or CTC, nine people would be diagnosed with cancer
and three would die if the tests were done every five years. Like colonoscopy,
CTC requires bowel preparation, but otherwise is not as invasive.
The less-invasive screening methods would each cause about half as many
complications as colonoscopy - affecting one percent of patients versus two
percent, according to findings published Monday in the Annals of Internal
Medicine. Those complications include bleeding and colon perforations. "All
of these methods will work if your ultimate goal is to reduce deaths from colon
cancer," said gastroenterologist Dr. David Weinberg from Fox Chase Cancer
Center in Philadelphia, who wrote an editorial accompanying the study.
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According to the NCI, about 143,000 people are expected to be diagnosed
with colon or rectal cancer in 2012, and close to 52,000 will die of the
disease. Weinberg said one of the advantages of colonoscopy is that it finds
pre-cancerous polyps that can be removed before they turn into cancer. Fecal
blood tests, on the other hand, typically catch very early cancers, so more
patients screened that way will get cancer and need treatment, although they'll
have a good prognosis.
Colonoscopy is also more expensive than other options, at a bit over
$1,000 a pop - and getting the procedure is typically not the most pleasant
experience. A fecal test costs $20 to $50, and CTC about $500. "If
everybody gets a colonoscopy, you will have many fewer people who ever develop
colon cancer, but you're going to pay a lot more money to get that
effect," Weinberg told Reuters Health. "What people and populations
have to decide is, how do you want to spend your money?"
Although it's a limitation that the results are based on a mathematical
model and not on screening and outcomes for real people, Weinberg said a
comparable human study will likely never be done because of the time and money
required. Based on the available evidence, the United States Preventive
Services Task Force, a government-backed panel, recommends screening for colon
cancer using colonoscopy, sigmoidoscopy or fecal occult blood testing between
age 50 and 75. Although both colonoscopy and fecal blood tests are available
most places in the U.S., other tests including CTC may be harder to find, or
not reimbursed by insurance, according to Weinberg.
SOURCE: Annals of Internal Medicine and Chicago Tribune
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