Colon Cancer: Screening Options
Colorectal cancer is the fourth most common cancer and the second leading
cause of cancer death in the U.S.
Fortunately, it is also one of the few cancers that is preventable.
your BCH provider about which screening is right for you. Regular screening is one of the
most powerful ways to prevent colorectal cancer. If polyps are found during
colorectal cancer testing, they can usually be removed before they have
the chance to turn into cancer. Testing can also result in finding cancer
early, when it’s smaller and might be easier to treat.
Colonoscopy has the highest sensitivity for detecting both cancerous and precancerous
lesions, prevents colon cancer by polyp removal, and remains the gold
standard test. The preps are now easier, the procedure is essentially
painless, and with a negative colonoscopy, no other screening is generally
needed for 10 years. Colonoscopy uses a flexible lighted tube with a small
camera on the end to look at the entire length of the colon and rectum.
If polyps are found, they may be removed during the test. To prepare for
the test, you may be asked to follow a special diet for a day or two before
the test. You will also need to clean out your colon with strong laxatives
(called a bowel prep) and sometimes with enemas, as well. Most people
are sedated during the test. If nothing is found during the test, you
won’t need another one for 10 years.
Second-tier options include the at-home FIT test:
Guaiac-based fecal occult blood test (gFOBT) and fecal immunochemical test (FIT) are used to find tiny amounts of blood in the stool that could be a sign
of cancer or large polyps. People take these tests at home with a kit
they receive from their doctor’s office, along with instructions.
A positive result will need to be followed up with a colonoscopy. However,
many times the cause is a non-cancerous condition, such as ulcers or hemorrhoids.
Stool tests like these need to be done every year.
FIT/Stool DNA test (i.e., cologuard) is a newer option. It does have the advantage of every
3 year testing. Remember, though, that these tests are not as accurate
in detecting precancerous polyps as colonoscopy. Stool DNA testing is
a type of non-invasive test to check for colorectal cancer. A stool DNA
test may appeal to people who want to be screened, but don’t want
to undergo the usual preparation required for a colonoscopy and some other
screening tests. It looks for certain gene changes that are sometimes
found in colorectal cancer cells. The patient uses a take-home kit to
collect a stool sample and mail it to a lab. Cologuard® is the name
of the stool DNA test that is currently FDA-approved, and the patient
gets it from their doctor’s office. The test checks for DNA changes
that could be a sign of cancer or pre-cancerous growths called polyps.
It also checks for blood in the stool, which can be a sign of cancer.
No special diet or bowel preparation (no laxatives or enemas) is required
for a stool DNA test. However, if the test does show a possible cancer
or pre-cancer, the patient would then need a colonoscopy to confirm it,
and possibly to remove any polyps.
Not everybody can have this type of screening test. It’s only for
people with an average risk for colorectal cancer: no personal history
of pre-cancerous polyps, colorectal cancer, or some other factors. Ask
your doctor if it's right for you.
Third-tier options include CT colonography every 5 years, flexible sigmoidoscopy combined
with FIT or FIT/DNA, but these tests are not as accurate in detecting
precancerous polyps as colonoscopy.
Flexible sigmoidoscopy is much like colonoscopy, but looks at only part of the colon and rectum.
If polyps are found, they may be removed during the test, or you may need
to have a colonoscopy later. Bowel prep may be required, but is not as
extensive as the one used for colonoscopy. Most people do not need to
be sedated during this test. If polyps or suspicious areas are seen, a
colonoscopy will be needed to look at the rest of the colon. Flexible
sigmoidoscopy must be done every 5 years.
CT colonography (also called virtual colonoscopy) is a scan of the colon and rectum that
produces detailed cross-sectional images so the doctor can look for polyps
or cancer. It requires bowel prep, but no sedation. Air is pumped into
the rectum and colon, and then a CT scanner is used to take images of
the colon. If something is seen that may need to be biopsied, a follow-up
colonoscopy will be needed. CT colonography must be done every 5 years.
If you’re 50 or older, talk to your doctor about which screening
test is right for you and get tested as often as recommended. If you're
under 50, talk to your doctor about your family medical history. People
at higher risk for colorectal cancer because of family history or certain
health conditions (such as inflammatory bowel disease) might need to start
Call 303-415-4015 to make an appointment with a BCH provider.