Screening & Detection
Nearly all cases of colorectal cancer begin with the growth of polyps, or benign growths of tissue, in the intestine.
If these growths are detected and removed early, the development of colorectal cancer can be prevented.
Men and women over 50 should be screened, as 90% of colorectal cancers occur in patients over age 50 and the risk increases with age.
Other family members of individuals with colorectal cancer or polyps should also be screened.
There is some controversy over how much of the colon needs routine examination and how frequently the exams should be carried out.
Sigmoidoscopy allows examination of the lower third of the large bowel.
At colonoscopy, the entire colon is examined from the anus all the way to the ileocecal valve, the junction of the small intestine and the colon.
About 65% of all precancerous polyps are found in the distal (lower) third of the colon which is within reach of the sigmoidoscope.
Those who favor sigmoidoscopy believe that if no polyps are present in the sigmoid colon they are unlikely to exist in the remainder of the colon and therefore, feel that colonoscopy for such individuals is unnecessary.
The opposing viewpoint takes nothing for granted, believing that the only way to be certain the colon is free of precancerous polyps is to examine it completely.
The motivating factor behind this controversy is often economic.
Colonoscopy is a more involved and expensive procedure than sigmoidoscopy.
Those responsible for paying for colorectal screening procedures usually support the use of sigmoidoscopy, if anything, over the performance of routine full colonic examination.
Q: Who Should Receive a Screening for Colorectal Cancer?
A: A standard screening program for a healthy individual over 50 years of age with no history or family history of colorectal cancer or polyps migh include:
- Fecal occult blood test annually, with sigmoidoscopy every 5 years, OR
- colonoscopy every 5 to 10 years, OR
- double contrast barium enema every 5 to 10 years combined with sigmoidoscopy.
A digital rectal examination should also be done regularly by your primary care physician or gynecologist
Q: How is Colorectal Screening Performed?
A number of tests are available to screen for colorectal polyps or cancer.
The following may be used alone or in combination with each other:
-
Fecal Occult Blood Test (FOBT)
This test checks for occult (hidden) blood in the stool.
- Flexible Sigmoidoscopy
In this examination, a doctor examines the inside of the rectum and lower portion of the colon through a flexible, lighted tube.
The doctor may remove polyps and collect samples of tissue or cells for closer examination.
- Colonoscopy
Colonoscopy is used to detect precancerous colon polyps before they become malignant.
In this examination, a doctor looks at the inside of the rectum and entire colon through a flexible, lighted tube.
The doctor may remove polyps and collect samples of tissue or cells for closer examination.
FAQs about Colonoscopy.
- Double Contrast Barium Enema
The patient is given an enema containing a dye (barium), followed by an injection of air.
X-rays of the rectum and colon are then taken.
The barium outlines the intestine on the x-ray film, so that polyps and other abnormalities may be easily seen.
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