| FAP |
| Colon Cancer in People With FAP |
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By
Miriam Komaromy,
MD
Reviewed
by Peggy Conrad,
MS, CGC and Jonathan
Terdiman, MD
Last updated August 10, 2000
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Familial
adenomatous polyposis (FAP) — a hereditary syndrome
triggered by defects in a specific gene — accounts
for approximately one percent of all colon cancer cases
diagnosed. Although approximately two-thirds of FAP
cases occur in patients with a family history of FAP,
the rest of cases occur as a new mutation in patients
with no family history of the syndrome.
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Symptoms:
Polyp
Proliferation
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| Polyps
often cause no physical symptoms. |
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People
with FAP almost always develop hundreds or even thousands
of colorectal polyps at a very early age. Although
these polyps are physical signs that colon cancer will
develop, polyps cause no physical symptoms and a person
with polyps is likely to be unaware of their presence,
except in rare cases where they cause visible bleeding
or symptoms of intestinal blockage.
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click
image for larger representation
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Because
people with FAP develop so many polyps at such a young
age, it is almost inevitable that some of these polyps
will develop into colon cancer. For
this reason, people with FAP generally develop colon
cancer at a much younger age than members of the population
at large. Polyps
usually begin to appear around puberty, but can occur
in children as young as age four. More than 95 percent
of people with FAP will have polyps by the age of 30.
The average age of onset of colon cancer for people
with FAP is 39, compared to 65 for the rest of the population.
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Screening
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| Doctors
recommend that people with FAP be regularly screened
for polyps beginning at age 10. |
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If you have FAP, you are at extreme risk
of developing colon cancer, and doctors recommend that
you be regularly screened for polyps beginning at age
10. Sigmoidoscopy
is recommended every year until polyps actually develop.
This is a
procedure in which a thin, flexible tube with a light
and viewing camera at one end is placed in the anus and
guided along the lower third of your colon.
If polyps do develop, your doctor may recommend that you
have an annual colonoscopy
(a more thorough procedure that allows a doctor to examine
the entire length of the colon). Once polyps are detected,
your doctor will help you decide when to remove them and
which type of surgery is most appropriate.
Coming from a family that is at risk for FAP does not
mean that you will necessarily have to undergo these rigorous
screening procedures. If the mutation in your family can
be identified, and if you do not carry the mutation, your
recommended screening procedures for colon cancer would
be similar to those recommended for the general population. |
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Prevention
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after a member of a FAP family develops polyps in the
colon or rectum, experts recommend that the patient's
colon be surgically removed, because he or she is at such
high risk of developing cancer. There are several surgical
options for this, some of which involve removal of the
rectum as well as the colon, since people with FAP can
still develop cancer in the rectum even after the colon
has been removed. |
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References
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Petersen,
G., et al. (1999). Genetic testing and counseling for
hereditary forms of colorectal cancer. Cancer
86: 1720-30
Galle, T. et al. (1999). Causes of death in familial
adenomatous polyposis. Scand J Gastroeneterol
34(8): 808-12.
Kuwada, S. and Burt, R. (1996). The clinical features
of the hereditary and nonereditary polyposis syndromes.
Surgical Oncology Clinics of North America 5(3):
553-67.
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