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 What is a screening test?
What is Virtual Colonoscopy?
Why is colorectal screening important?
What are the current methods used to
detect polyps?
How is it done?
Is virtual colonoscopy painful?
What are the current practice guidelines?
Will my insurance company reimburse me?
When and how often do I need to have
a test to screen for polyps?
What is a screening test?
A screening test helps detect cancer at an early stage, before it causes symptoms
in the patient. Many cancers become more difficult to treat as they progress,
making the need for early detection especially important. In particular, colon
cancer can often be prevented entirely by removing growths known as polyps
before they become cancerous. Typically, patients undergoing a screening test
lack any direct symptoms of the disease or cancer in question, though they
may have certain risk factors (e.g. family history, predisposing diet, etc.).
What is Virtual Colonoscopy?
Virtual colonoscopy is a promising new screening test for colorectal cancer.
It is method to detect tumors and precancerous lesions (polyps) in the colon.
Virtual Colonoscopy relies on advances in CT (CAT scan) to produce high quality
pictures of the colon. A radiologist, a physician with advanced training
in medical imaging, then uses special computer software to examine the images
for polyps. Virtual colonoscopy eliminates the need to insert a long tube
into the colon (as with Conventional Colonoscopy) or fill the colon with
liquid barium (as with Barium Enema). Research performed at many centers
across the country has provided substantial evidence that Virtual Colonoscopy
is better able to detect polyps than Barium Enema and is nearly as accurate
as Conventional Colonoscopy. In addition, most patients report that Virtual
Colonoscopy is more comfortable than either Barium Enema or Conventional
Colonoscopy.
Why is colorectal screening
important?
Colorectal cancer (CRC) is a leading cause of cancer-related death in the United
States. Each year, 65,000 people in the United States die from the disease,
while 155,000 new cases are diagnosed. Early detection of CRC improves survival
dramatically. Colon cancer can be prevented if polyps are discovered and removed
early. Tumors take years to develop. Polyps, when detected, can be removed
preventively.
What are the current methods
used to detect polyps?
Several government agencies, as well as the American Cancer Society, recommend
that patients undergo a screening test at age 50 that allows the physician
to look at the entire length of the colon.
Currently there are two standard methods for
visualizing the entire colon: Conventional Colonoscopy and
Barium Enema. Several other tests exist, such as sigmoidoscopy,
but these procedures show only a portion of the colon. Both Barium
Enema and Conventional Colonoscopy have drawbacks, however. Barium
Enema’s accuracy is questionable and many patients find it
uncomfortable. Conventional Colonoscopy is associated with increased
risk and cost, and in 10% of cases, fails to show the entire colon.
In addition, Conventional Colonoscopy may cause an injury of the
colon (tear or perforation) in one of 1500 patients. Since patients
must be sedated, they cannot resume normal activities immediately
after the exam.
How is it done?
In the 24-hour period prior to the exam, patients follow a special regimen
to cleanse their bowel of stool and excess fluid. Typically, this regimen
includes taking a laxative and abstaining from solid foods (certain specially
formulated solid foods are available). The day of the test, they come to
the hospital for a CAT scan. At the start of the procedure, a small rubber
tube is inserted into the rectum so that the colon can be filled with air.
A CAT scan is then performed while the patient lies comfortably. The total
time required for the study is approximately 10-20 minutes. Because sedation
is not required, patients are free to leave the CT suite immediately without
the need for observation or recovery. Patients can resume normal activities
immediately after the procedure and can eat, work or drive without a delay.
Is virtual colonoscopy painful?
When air is introduced in the colon, some patients experience temporary abdominal
cramping or discomfort.
What are the current practice
guidelines?
It is important to understand the role of virtual colonoscopy in screening
for colorectal cancer. Virtual colonoscopy is an alternative to, not substitute
for, conventional colonoscopy. It is appropriate for individuals unwilling
to undergo conventional colonoscopy and patients who, for a number of reasons,
cannot or should not undergo conventional colonoscopy. As with any medical
examination, the decision to undergo CT colonography should be made in consultation
with a physician. Patients should always involve their primary care physicians
in the screening process.
Will my insurance company reimburse
me?
Most insurance companies do not currently reimburse virtual colonoscopy. As
a result, patients will have to assume the cost of the procedure themselves.
The cost at the Brigham is insert price when finalized.
When and how often do I need
to have a test to screen for polyps?
Patients over 50 years old should be tested every five to seven years with
a Barium Enema, Conventional Colonoscopy, or Virtual Colonoscopy.
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