Health & Nutrition
Colorectal Cancer ScreeningColorectal cancer is the second most prevalent cancer in
the United States. In 2001, there
were an estimated 135,400 new cases and 56,700 deaths from the disease.
Yet according to a 1997 survey, less than 30 percent of eligible people
had been screened.
The risk for developing colorectal cancer increases with
advancing age. Risk factors include having inflammatory bowel disease, a
personal or family history of colorectal cancer or colorectal polyps, and
certain hereditary syndromes. Lack of regular physical activity also contributes
to a person's risk for colorectal cancer. Other factors that might contribute to
the risk for colorectal cancer include low fruit and vegetable intake, a
low-fiber and high-fat diet, obesity, alcohol consumption, and tobacco use.
Reducing the number of deaths from colorectal cancer
chiefly depends on detecting and removing precancerous colorectal polyps as well
as detecting and treating the cancer in its early stages.
Colorectal cancer can be prevented by removing precancerous polyps, which
can be present in the colon for years before invasive cancer develops.
Colorectal screening techniques includes colonoscopy,
sigmoidoscopy, fecal occult test (FOBT), and barium enema with air contrast.
In the digital rectal exam (DRE), a doctor
uses a finger to check for any abnormal growths in the lower rectum.
The DRE is not sufficient for colorectal cancer screening.
The fecal occult blood test (FOBT) looks for hidden
(“occult”) blood in the stool that may indicate cancer or a polyp.
It's relatively convenient and inexpensive, but not adequate for
colorectal cancer screening by itself.
Sigmoidoscopy is a procedure for visually inspecting
the lower (sigmoid) colon with a flexible lighted tube, or colonoscope.
It takes five to 10 minutes and generally examines the lower 1/3 to ½ of
the colon.
During colonoscopy, the doctor uses a flexible,
lighted instrument tipped with a camera lens to examine the entire colon.
It takes about 25 to 30 minutes. The
doctor can also use the instrument to remove polyps.
Barium enema with air contrast is a technique for
imaging the inside of the colon with X-rays, as opposed to directly examining it
with a colonoscope. It is not very
sensitive for detecting large polyps, limiting its use.
Several scientific organizations recommend regular
screening for all adults aged 50 years or older. Recommended screening
procedures include the following three tests:
- FOBT every year.
- Flexible sigmoidoscopy every 5 years.
- Total colon examination by colonoscopy every 10 years or by air-contrast barium
enema every 5–10 years.
Persons at higher risk should begin screening at a younger
age and may need to be tested more frequently.
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