Hereditary non-polyposis colorectal cancer
HNPCC is an inherited bowel cancer syndrome that accounts for approximately 1-5% of bowel cancers.
Below is an overview of HNPCC (also known as Lynch
Syndrome).
For more detailed information about HNPCC,
please
download the HNPCC
Information Guide.
You may print copies of the guide to pass on to family and
friends. Please note, this guide does not replace your discussions
with doctors, genetic counsellors, nurses and other health
professionals.
What is HNPCC?
- HNPCC is an inherited bowel cancer syndrome that accounts for
approximately 1-5% of bowel cancers.
- Although the name - hereditary non-polyposis colorectal
cancer - suggests people will not develop polyps, people
affected by HNPCC are at risk of developing bowel polyps, just in
small numbers. The term "non-polyposis" is used to distinguish
HNPCC from another hereditary bowel cancer condition called FAP, in
which 100s to 1000s of bowel polyps develop.
- HNPCC is caused by a change in a gene that normally functions
to protect a person from getting cancer. If you have a parent or
sibling with HNPCC, you are potentially at risk of developing
HNPCC. If you have been diagnosed with HNPCC, your children are at
risk. When a parent carries the changed gene, they have one working
and one non-working copy of the HNPCC gene. Each child will
independently have 50% chance of inheriting the gene fault.
- Not everyone with the gene change will develop bowel cancer. A
person who inherits this gene change has up to an 80% chance of
developing bowel cancer by the time they are aged 80 unless
preventative measures are taken. Developing bowel cancer at a young
age is not uncommon.
- Not all people with HNPCC have a family history of HNPCC. Some
people may be the first in their family to get HNPCC. If you are
the first one in your family to get HNPCC, each of your children
still have the same 50% chance of inheriting the gene change.
- In men and women with HNPCC, cancers can also occur in the
kidney, ureter (the tube from the kidney to the bladder) and in
parts of the gut such as the small bowel (intestine), stomach or
pancreas.
- Women also have an increased risk of cancer of the inner lining
of the uterus (womb) and the ovaries, although the risk of bowel
cancer is higher.
Management
Regular check-ups
If you are a member of a family affected by HNPCC you should
have regular bowel screening beginning in your early to mid-20s.
For this procedure - called a colonoscopy - a specialist uses a
long flexible tube to examine the lining of your colon (large
intestine) for any polyps or signs of cancer.
Women from the age of 35 may need annual screening of the uterus
and ovaries in the form of ultrasounds and blood tests.
Genetic testing
- Researchers have identified some of the gene changes that cause
HNPCC.
- If a gene change is identified amongst your family (in someone
who has HNPCC), other relatives at risk of carrying the gene change
can be tested.
- Sometimes the changed gene is not found in the family. This
means that in your case, HNPCC may be due to other gene changes
that research has not yet identified. If the family gene change is
not found, genetic testing is not able to be offered to other
family members.
- If a family gene change is found, the rest of the family can be
offered predictive testing. This means testing to see if you have
inherited HNPCC by checking whether or not you have the gene change
even though you may not have any signs or symptoms yet.
- A blood test is needed for genetic testing. For further
information speak with a Genetic
Counsellor.
For more information on hereditary cancer, please visit eviQ and click on the
Cancer Genetics tab.
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