Colon cancer: Symptoms and screening
While many people show no symptoms of colon cancer (or polyps), some people with colorectal
polyps or colorectal cancer do have symptoms. These may include:
- Blood in or on your stool (bowel movement).
- Pain, aches, or cramps in your stomach that happen often with no apparent cause.
- A change in bowel habits, such as having stools that are narrower than usual.
- Unexplained loss of weight.
If you have any of these symptoms, talk to your doctor. These symptoms can be caused by something other than colon cancer. Your doctor is critical in the screening and diagnosis.
Types of colon cancer screening
Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the
colon or rectum. Several tests can be used alone or in combination to screen for colorectal cancer.
Following are test descriptions from the Centers for Disease Control/Division of Cancer Prevention,
with recommended frequency for each different type:
Fecal occult blood test (FOBT)
This test checks for occult (hidden) blood in the stool. At home, you place a small amount of
your stool from three consecutive bowel movements on test cards. You return the cards to your
doctor's office or to a lab where they're checked for blood. This test is
recommended yearly. (If blood is found, you likely will need a follow-up
colonoscopy.)
Flexible sigmoidoscopy
Before this test, you use a strong laxative and/or enema to clean out the colon.
Flexible sigmoidoscopy is conducted at the doctor's office, in a clinic or at a hospital. The
doctor (or other specially trained health care professional) uses a narrow, flexible, lighted tube
to look at the inside of the rectum and the lower portion of the colon. During the exam, the doctor
may remove polyps (abnormal growths) and collect samples of tissue or cells for closer examination.
This test is
recommended every five years. (If polyps are found, you will need a follow-up
colonoscopy.)
Combination of FOBT and flexible sigmoidoscopy
Some doctors recommend having both the FOBT and flexible sigmoidoscopy to increase
the chance of finding polyps (abnormal growths) and cancers. When used in combination, FOBT is
recommended yearly and flexible sigmoidoscopy is
recommended every five years.
Colonoscopy
Before this test, you will take a strong laxative to clean out the colon.
Colonoscopy is conducted in a doctor's office, in a clinic or at a hospital. You are given a
sedative to make you more comfortable, while the doctor uses a narrow, flexible, lighted tube to
look at the inside of the rectum and the entire colon. This test is similar to flexible
sigmoidoscopy, except that the tube used is longer and allows the doctor to see the entire colon.
During the exam, the doctor may remove polyps (abnormal growths) and collect samples of tissue or
cells for closer examination. This test is recommended every 10 years. (Colonoscopy is also used as
a follow-up test if anything unusual is found during one of the other screening tests.)
Double-contrast barium enema
This test is conducted in a radiology center or at a hospital. Before the test, you
use a strong laxative and/or enema to clean out the colon. For this procedure, you are given an
enema with a barium solution, followed by an injection of air. An X-ray of the rectum and colon is
then taken. The barium coats the lining of the intestines so that polyps and other abnormalities
are visible on the X-ray. This test is
recommended every five years. (If polyps are found, you will need a follow-up
colonoscopy.)