Routine screening allows for the early
detection of colorectal cancer while it
is still highly curable, as well as the detection of growths, or polyps, that might eventually become cancerous.
The disease affects tens of thousands of
Americans each year, most of which develop the disease after age 50. “Colorectal
cancer occurs in approximately 130,000
Americans yearly,” says Dr. Bennett Roth,
chief of clinical gastroenterology, director
of the Digestive Disease Center and medical director of the UCLA Center for
Esophageal Disorders. “It is the third most
common cancer and the third leading
cause of cancer death in women and second most common in men.”
Smart Business spoke with Roth about
colorectal cancer, who should be screened
and what procedures are available.
What is colorectal cancer?
Colorectal cancer (CRC) is a malignancy
arising from the lining of the colon or rectum that, if undiagnosed and untreated,
will potentially lead to obstruction of the
bowel, bleeding and/or spread to vital
organs, such as the liver. The majority of
CRCs begin as benign polyps, which may
mutate over time into malignancies. While,
perhaps, no more than two out of 1,000
polyps become malignant, there is no way
to know which of these will, and therefore,
it is recommended that most polyps be
removed, once they are identified.
What are the symptoms of colorectal cancer?
Many colon cancers may be asymptomatic and discovered only at the time of
screening. Presenting symptoms include
abdominal pain, change in bowel pattern,
rectal bleeding or iron deficiency anemia.
Unfortunately, the prognosis o those
patients presented with such symptoms is
less favorable than when this disease is
found in an earlier, asymptomatic stage.
Who should be screened?
It is recommended that everyon be
screened for this disease. The primary goal
of screening is to discover the forerunners
of cancer, i.e. polyps or, at the least, cancer
in its earliest stages. For those individuals
lacking significant increased risk factors, screening is recommended initially at age
50. For those with first-degree relatives
having history of CRC diagnosed before
age 60, screening should be initiated at age
40. For those with two or more first-degree
relatives having CRC or a first-degree relative with early onset CRC (before age 50),
screening should begin at an age equivalent
to 10 years prior to the age of onset of the
relative’s cancer. Follow-up screening is
dependent upon the findings at the time of
the index examination as well as the type
of screening performed.
What types of screening tests are available?
Fecal occult blood testing (FOBT) is
recommended yearly. If positive, a full
colonoscopy is recommended. This strategy leads to a reduction of mortality from
CRC of 33 percent over 13 years. Unfortunately, while the sensitivity of the test
is high — greater than 90 percent — the
specificity is low. Therefore, the major benefit of this strategy is in identifying those in
need of a colonoscopy.
Flexible sigmoidoscopy is a limited
endoscopic examination of the rectum and
lower portions of the colon. It is often combined with FOBT as a screening strategy.
Unfortunately, 40 to 50 percent of polyps may arise proximal to the reach of this
examination and, if unassociated with a
positive FOBT, may be undetected.
Barium enema is a relatively limited and
rarely used means of screening. There are
no studies demonstrating efficacy of this
modality although it is included in the list
of available screening tests.
Colonoscopy has become the primary
screening modality for most patients. It has
greater than 90 percent sensitivity and
affords the opportunity for obtaining biopsies as well as the removal of polyps.
What is the appropriate interval level for follow-up screening?
For average-risk patients, if no polyps are
found, repeat examination at 10-year intervals is recommended until age 80 — unless
medical co-morbities indicate potential
reduction in life expectancy or excessive
procedural risk to warrant cessation of
screening. If polyps are detected, follow-up
examinations may be recommended at
three- to five-year intervals, depending
upon the number, size and type of polyps
discovered. If a cancer is found and treated, a follow-up colonoscopy should be
done at the one-year anniversary and, if
negative, at three years and every five
years thereafter. For those at increased
risk (family history of sporadic CRC),
screening at five-years intervals is recommended. For those with extremely high
risk (familial cancer syndromes), screening every two years may be recommended.
How helpful are these tests in detecting colorectal cancer in its early stages?
Screening has been shown to reduce the
incidence and mortality of CRC by as much
as 35 to 75 percent. Unfortunately, only 45
to 55 percent of adults in the U.S. have
been appropriately screened. This is the
result of many factors including lack of
public awareness, fears and concerns
about the nature of screening tests, physician apathy, and inadequate insurance or
third-party coverage. The statistics are
even worse for racial and ethnic minorities.
DR. BENNETT ROTH is chief of clinical gastroenterology,
director of the Digestive Disease Center and medical director of
the UCLA Center for Esophageal Disorders. Reach him at
[email protected].
Chief, clinical gastroenterology
Director, Digestive Disease Center
Medical director, UCLA Center for
Esophageal Disorders