Colon Cancer Usually Preventable if Older People
Just Step Up to Screening
Researchers working to make screening less
invasive, more accurate
By Nicole Fawcett
Colon Polyp
March 28, 2008 - Colon cancer screening is a tough
sell. Its icky, uncomfortable and the thought of a
colonoscopy, especially the prep, can be intimidating, to say the
least.
But heres what clinches the sale:
Colon cancer can be largely prevented through proper screening.
Researchers, including those at the
University of Michigan Comprehensive Cancer Center, are working to
make colorectal screening a little easier, through a combination of more
choices and less-invasive procedures.
Colorectal cancer is the second biggest cancer
killer in both men and women, surpassed only by lung cancer. Some
148,810 Americans will be diagnosed with colorectal cancer this year,
and 49,960 people will die from the disease.
A new imaging technique shows
fluorescent-labeled peptides binding to cancerous cells (labeled
dysplastic crypt) but not to normal cells (normal crypt).
U-M colorectal cancer specialists are working to
raise awareness of the disease and the importance of prevention. March
is Colon Cancer Awareness Month.
In recent years, efforts to increase awareness have
led to slow and steady climbs in screening rates. New data released this
month by the
Centers for Disease Control and Prevention showed 60.8 percent of
adults were current with colorectal cancer screening recommendations in
2006, compared with 53.9 percent in 2002. But these numbers lag
significantly in comparison with other cancer screening tests, such as
mammography or Pap smears.
Its important to be screened routinely for colon
cancer, and there are a variety of tests available to help do that. If
we reached full compliance with colon cancer screening, we could prevent
more than 90 percent of colon cancers, says
D. Kim Turgeon, M.D., clinical associate professor of internal
medicine in the division of gastroenterology at the
U-M Medical School.
Turgeon and other researchers are continuing to
look for less-invasive screening methods to encourage more people to get
the test. One potential option researchers are looking at is a test to
look for markers in blood or stool that might suggest colon cancer. Then
only those with suspicious results would be referred for further tests,
such as colonoscopy.
In separate research,
Thomas D. Wang, M.D., Ph.D., assistant professor of internal
medicine and biomedical engineering at U-M, reports this week in
Nature Medicine on a potential new technique to screen for colon
cancer.
American Cancer Society estimates over 147,000 new
cases and 57,000 deaths this year
Dec. 10, 2007
The method involves topically applying a type of probe called a
peptide, that is labeled with a fluorescent agent. The peptide is
designed to target pre-cancerous changes in the colon.
Then, using a
special microscope that fits through a standard medical endoscope, a
doctor can spot these suspicious lesions.
Theres been a lot of effort behind screening
patients for polyps that you can see with a white light endoscope. But
if the cancerous or precancerous lesions are flat, you cant see them
with standard screening techniques. We are using advanced imaging to
look at molecular targets rather than structural changes. We hope this
approach will allow us to find more lesions than with conventional
colonoscopy, says Wang, who conducted the research while at
Stanford University.
The researchers found that the peptide bound to
pre-cancerous tissue 81 percent of the time. They hope to identify
additional peptides that would bind to other targets to increase this
methods promise.
Currently, screening guidelines include a choice of
four different tests:
>> Fecal occult blood test, which checks for
blood in the stool
>> Colonoscopy, the gold standard, in which
an instrument is inserted into the colon through the rectum
>> Flexible sigmoidoscopy, which examines
the rectum and lower colon using a different instrument
>> Double contrast barium enema, a series of
X-rays of the colon and rectum
This month, experts added two new screening tools
to the arsenal: Virtual colonoscopy, which uses a CT scan to look for
abnormalities; and a stool test that looks for DNA markers associated
with cancer. Neither test is currently covered by insurance, although
experts hope the CT colonography will be covered within a year.
Screening for colon cancer should begin at age 50
for people of average risk. Those with certain risk factors may need to
begin screening earlier. For information about colon cancer, visit
www.mcancer.org or call the U-M Cancer AnswerLine at 800-865-1125.
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