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Please note: This information is only a guide and should not replace the
advice of your physician. Always consult your physician for advice about your
personal colorectal cancer risk.
What is hereditary colorectal cancer?
The term hereditary colorectal cancer is used when multiple generations of a
family have colorectal cancer. Several genes that cause hereditary colorectal
cancer have been found. There may be other genes that have not yet been
discovered.
The two most common and well-described inherited colorectal cancer syndromes,
which can occur in both Jewish and non-Jewish families, include familial
adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC).
Patients with FAP develop hundreds of colon polyps at a young age, often have a
strong family history of colon cancer and will develop colon cancer if
preventative measures are not taken. HNPCC patients often have at least three
family members and two generations with colorectal cancer, and cancer develops
before age 50.
These two inherited cancer syndromes account for 5 percent to 10 percent of
all colorectal cancers.
What is familial colorectal cancer?
When colorectal cancer occurs in more than one family member, it may be due
to chance alone. However, it could mean that the potential risk for developing
colorectal cancer has been passed from one generation of the family to the next.
This means that relatives of a person with colorectal cancer may be more likely
to develop colorectal cancer.
Approximately 15 percent to 50 percent of colorectal cancer cases are
familial, which means that there is a tendency for colorectal cancer to develop
in the family. Familial colorectal cancer can be caused by a single gene, a
combination of genes, or a combination of genetic and environmental factors.
Typically, these families have more than one family member with a history of
colorectal cancer or pre-cancerous polyps.
The most recently identified gene mutation (change) that is associated with
colorectal cancer is called APC I1307K. This gene mutation is found in 6 percent
of the Ashkenazi Jewish population and 28 percent of Ashkenazi families with a
history of colon cancer, making it one of the more common cancer susceptibility
genes. Ashkenazi Jews make up more than 90 percent of the Jewish population in
the United States. The presence of this gene mutation increases a person’s
risk of developing colorectal polyps and cancer. The exact lifetime risk of
developing colon cancer in people who have this gene mutation is estimated to be
12 to 30 percent. Families in which this gene mutation occurs may or may not
have one or more family members with colorectal cancer or polyps.
Is there a test for the newly discovered I1307K mutation?
Yes, a gene test has been developed to look for this single gene mutation
associated with colorectal cancer in the Ashkenazi Jewish population. This test,
which is performed on a small sample of blood, does not rule out mutations that
cause other forms of hereditary colon cancer.
Who should be tested for the I1307K mutation?
The Cleveland Clinic Medical Genetics Program suggests that any person of
Ashkenazi Jewish descent should consider genetic counseling and testing if there
is a personal or family history of colon cancer or pre-cancerous (adenomatous)
polyps. A family history may consist of at least one close family member
(father, mother, brother or sister) who has had either colon cancer or
pre-cancerous polyps. People of Ashkenazi Jewish descent without a family
history of colorectal cancer may want to consider genetic counseling to
determine the value of testing, given their circumstances.
Who should not be tested for the I1307K gene mutation?
This test is not recommended for non-Ashkenazi Jewish individuals. People of
Ashkenazi Jewish descent are the only group that seems to carry this particular
mutation. This is because the genetic change probably arose spontaneously
several centuries ago and has been passed through generations of Ashkenazi Jews.
What does a positive I1307K gene test result mean?
If a person tests positive for this mutation, that person has an increased
risk of developing colorectal cancer in his or her lifetime. If a person already
has had colon cancer or polyps, it may affect screening (colon exam)
recommendations. This test does not detect the presence of cancer or polyps.
What does a negative I1307K gene test result mean?
If a person tests negative for this mutation, it means that they do not
carry this specific mutation found in Ashkenazi Jews. This person still may have
a mutation in another gene that causes hereditary colon cancer. Risk may be
evaluated through genetic counseling, where family history, lifestyle and other
issues may be discussed.
What should you do if you receive a positive gene test result?
Early diagnosis is important for the timely detection and prevention of
colorectal cancer. At this time, experts have made the following recommendations
for people who test positive for the APC I1307K mutation:
- People with a positive gene test should
have a routine colonoscopy every two years, beginning at age 35, or five to 10
years before the earliest age at which colon cancer or polyps occurred in your
family.
- People with a personal history of colon
cancer or polyps should have a routine colonoscopy every two years.
- Relatives of people testing positive
for this gene mutation should consider genetic counseling and testing.
Note: These recommendations may be subject to change, based on specific
family history information.
How can the gene test be obtained?
The test currently is performed at only a few centers throughout the country.
The Cleveland Clinic Foundation offers genetic counseling and a mutation
analysis for the APC I1307K mutation for people of Ashkenazi Jewish descent. The
test can be obtained through the Department of Medical Genetics at (216)
445-5686 or 800-998-4785.
How much does the gene test cost? Is the cost reimbursed by insurance?
The gene test currently costs about $300. The cost of genetic counseling is
an additional charge. The costs of the tests for the other types of inherited
forms of colorectal cancer (FAP and HNPCC) range from about $250 to $2000.
Some insurance providers cover genetic counseling and genetic testing, while
others do not. People interested in submitting the cost of the test to their
insurance providers should check with their providers about coverage before
having the test performed.
Is insurance discrimination a real risk for those pursuing the test?
With any predictive genetic test, there is potential for insurance
discrimination. However, there is a federal law (the Health Insurance
Portability and Accountability Act of 1996) that provides protection from
cancellation or higher premiums for people who are insured through group plans,
but no laws are in place for individual insurance plans. This law also prevents
genetic test results from being used as a "pre-existing condition,"
which helps to further protect people from discrimination. Legislation
protecting privacy of these patients has been developed in some states,
including Ohio.
These issues are carefully explained during the genetic counseling session,
before the patient chooses to undergo testing.
For more information
For more information about this gene test, please call the Cleveland Clinic
Medical Genetics Program at (216) 445-5686 or 800-998-4785 or visit our web site
at: http://www.clevelandclinic.org/cc/medgen/.
(This information was adapted from the Johns Hopkins Colorectal Cancer
Program APC I1307K information brochure)
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