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Screening, Early Detection the
Key to Colon Cancer Prevention
In the
fight against colon cancer we seem to have turned the
corner. For the first time we have seen a small but steady
decline in cancer rates. These improvements have resulted
from advances in cancer prevention, early diagnosis, and
treatment. Your primary care physician plays an active role
in this fight.
Colon
cancer is our nation’s second-leading cause of cancer death.
It strikes an estimated 135,000 Americans each year, causing
death for 55,000 people. Tragically, for many patients, a
delay in diagnosis is the primary reason for the advance
stage of the disease at presentation and is associated with
a poor outcome. Regular screening could have detected many
of these cancers at an earlier, more favorable stage.
It is not
appreciated by the public, but colon cancer is the only
major cancer that affects men and women almost
equally. There appears to be a misconception that it affects
mainly men. Women need to realize that they are equally at
risk, and that they need to undergo screening for it just as
they need to be screened for breast and cervical cancer.
Screening
is particularly valuable in the case of colon cancer because
the disease is readily detected and in its early stages is
highly treatable. When diagnosed before the onset of
symptoms, perhaps 85% of colon cancers are localized to the
bowel and can be cured by surgical excision. Once symptoms
have developed, the majority of the cancers have spread
beyond the bowel and the likelihood of surgical cure is only
30% to 40%.
Colon
cancer is rare in persons under age 40. Between ages 40 and
50 the incidence increases slightly; after age 50 the
incidence begins to rise substantially. For that reason, it
is recommended that screening for colon cancer start at age
50.
A fair
amount of colon cancer cases occur in families and appear to
involve inherited risk. The greater the number of
first-degree family members (parents, siblings, or children)
who have had colon polyps or cancer, and the younger the age
at diagnosis, the more likely it is that the patient has a
genetic predisposition to develop colon cancer. Instead of
screening, patients with a family history of the cancer
should undergo a complete colonoscopic evaluation of the
colon..
Screening
for colon cancer is appropriate only in patients without
symptoms; symptomatic patient clearly require more intensive
evaluation. The principal early symptoms of colon cancer are
abdominal pain or cramping, a change in bowel movement
pattern lasting more than a few weeks, and rectal bleeding.
At times,
the occurrence of rectal bleeding can pose a clinical
dilemma. The safest approach is to perform an evaluation for
cancer in a patient old enough to be a risk if the bleeding
occurs more than once or persists after hemorrhoid
treatment, or if the blood appears to be mixed with the
stool. The latter finding indicates that the bleeding
probably originates higher in the bowel.
The
screening tests currently recommended for men and women aged
50 or older without symptoms and with no other risk factors
are--to detect blood in the stool (fecal occult blood test)
every year, and a flexible sigmoidoscopy every five years. Sigmoidoscopy
is the visual examination of the inside of the rectum and
sigmoid colon. The colon (large intestine) is 5 to 6 feet
long. The flexible sigmoidoscopy has proved to be accurate
for diagnosing polyps and cancer in the distal one third of
the colon, the area where 60% to 70% of the cancers and
colon polyps occur. If either the sigmoidoscopy is abnormal
or there is blood in the stool, patients are often refereed
to a specialist who will perform a full colonoscopic
evaluation of the colon.
The
alternative to a colonoscopy is the barium enema and x-ray
study, plus a sigmoidoscopy if the patient has not already
undergone the latter. If these test results suggest the
possibility of cancer, the patient must then undergo
colonoscopy anyway. Thus, the barium study is not
necessarily a cheaper test: when the need for additional
colonoscopies is factored in.
Physicians
are encouraged to talk with their patients about the
prevalence of colon cancer, risk factors, and the importance
of screening for colon cancer. Health plans and employers
also have a vested interest in improving screening rates if
they are truly committed to maintaining employee
health. Reducing the incidence and mortality of colon cancer
is a realistic goal. To achieve this, however, we must find
incentives and
innovative ways to encourage people to participate in this
life saving screening process.
Content
of articles can only be used with writer attribution to Dr.
Kevin Weiland.
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