Key Points
- FAP is a rare condition associated with
multiple bowel polyps or outgrowths from the lining of the large bowel.
-
There are
different types of bowel polyps that can occur in the large bowel or colon. The
type of bowel polyp a person has is determined by looking at a sample (biopsy)
of the polyp under a microscope.
- People with FAP develop adenomatous bowel
polyps, hence the name of this condition.
- People with FAP usually develop multiple
large bowel polyps before the age of 20 years.
- Adenomas in the general
population do not usually occur until the age 40 – 50 years and then only in
small numbers.
- Without treatment, individuals with FAP will
inevitably develop bowel cancer in mid life.
- Cancer occurring in individuals
with FAP accounts for less than 1% of all bowel cancer.
- Bowel surgery prevents individuals with FAP
from developing bowel cancer. This surgery is normally recommended in the later
teenage years.
- Yearly bowel screening is
required for the part of the large bowel that remains to prevent cancers
developing.
- People with FAP have up to a 4 -
5% risk of developing upper gastrointestinal cancer in their lifetime and should
have regular upper gastrointestinal endoscopy from the age of 25- 30 years.
- FAP is caused by an alteration
in the APC gene. The alteration in the gene means that it cannot do its job
properly.
- Up to 30% of people with FAP do not have a
family history of the condition, i.e. they are the first person in their family
to develop an alteration in the APC gene.
-
Once present, FAP is a dominantly
inherited condition. This means that if you have FAP each of your children has
a 1 in 2 (50%) chance of developing FAP.
- Genetic testing to try and
identify an abnormality in the APC gene is available for families with this
syndrome.
- The aim of the NZFGICS is to
reduce the number of cancers occurring in families by facilitating the required
bowel screening for registered families.
What is FAP?
FAP is an inherited condition which
causes people to develop multiple (usually at least a 100) adenomatous bowel polyps. Bowel cancer
develops from adenomatous bowel polyps over a period of time. Individuals with FAP will inevitably develop
bowel cancer without surgery to remove the majority of their large bowel.
What is the risk of developing
bowel cancer in FAP?
Almost all individuals with FAP will
develop bowel cancers by their late thirties and forties. This differs from other people who tend to be
over the age of 50 years when they develop bowel cancer.
What is attenuated FAP (AFAP)?
Some families have attenuated FAP
(AFAP). This is a later onset type of
FAP. Individuals with AFAP develop fewer
polyps at a slightly older age than those with typical FAP. Although people with AFAP tend to develop
colon cancer at a later age, they still have a very high lifetime risk of colon
cancer.
What are the bowel symptoms of
FAP?
In FAP polyps usually start to
develop throughout the colon, before the age of 20 years. Adults may have hundreds to thousands of
polyps. There may be no symptoms to
alert you that you have bowel polyps. The major concern is that the polyps will
become cancerous.
Does FAP have other effects on the body?
FAP can have other effects on the
body as well as causing bowel polyps.
Polyps are commonly seen in the stomach but these are a different type
of polyp and are usually harmless. Some
people with FAP get skin cysts or harmless bumps on their bones. or Freckle-like
spots on the inside lining of the eye, which we call CHRPE, can also occur but these do not affect vision in any way.
A small number of people with FAP
will develop benign growths in their abdomen called desmoid tumours. Occasionally they cause problems but they do
not become cancerous.
There is no need to have regular
checks for desmoids but if you have any skin or bone lumps or unexplained
symptoms, you should discuss them with your General Practitioner (GP) or let
your specialist know at your next visit.
What causes FAP?
In FAP, part of a gene called APC is
altered, so it cannot do its job properly.
People with FAP have one working copy and one altered copy of the APC
gene. The altered copy of the gene is
responsible for the development of the large bowel adenomatous polyps.
Who is at risk of FAP?
When you have FAP each of your
children has a 1 in 2 (or 50%) chance of inheriting it.
What does the genetic test
result mean for my family?
The gene involved in FAP (called
APC) is like a very long instruction sentence.
A spelling mistake or alteration in
any part of this instruction can cause FAP.
Each family with FAP will have a different alteration but the
individuals within the family will have the same alteration which is called a
mutation. We can look in a blood sample
from someone who has FAP to try to find the alteration in a family.
If we do find a genetic mutation we
can test other family members to see if they have inherited it. We recommend that children have a genetic
test around the age of 12-14 years to see if they have inherited the altered
gene.
If they have not inherited the
altered FAP gene, they do not need FAP related bowel checks but if they develop
bowel symptoms then like anybody else they need to see their GP.
Individuals who have not inherited the
altered FAP gene will not be able to pass the altered gene on to their children
in the future.
If an individual has inherited the
altered FAP gene it is important that they have bowel checks every year
starting from the age of 14-15 years.
What if no spelling mistake is
found?
If we don’t find a gene alteration
we won’t be able to offer a genetic test to other relatives but they will still
need bowel checks. This is generally
advised from teenage years but we will discuss the best screening plan for your
family with you.
Most people with FAP develop polyps,
usually in the teenage years. However,
if genetic testing is not available and an individual at risk of having FAP has
been having regular colonoscopy and no bowel polyp shave been identified by the age of 50 years it is unlikely that
they have FAP. In this situation the the regular bowel checks would stop.
However, even when the bowel checks have stopped if an individual develops new
bowel symptoms they may still need to be investigated because they can still
get bowel problems like anyone else in the general population,
What bowel screening checks do
I need and how often do I need it?
Most people who have FAP begin to
develop polyps in their early teens.
People at risk of FAP should start bowel checks between 14 and 15 years
of age. These should be repeated every
year. It is important to remember that
it is not safe to simply wait for symptoms to develop. It is vital that children at risk of FAP have
regular bowel checks even if they do not have symptoms.
Do I need other checks?
Most individuals with FAP develop polyps
in the first part of the small bowel (duodenum) by the time they are in their
seventies but only a small percentage
(approximately 5%) develop duodenal
cancer.
A tube test examination of the stomach
and first part of the small bowel (gastroscopy) is recommended from the age of 25-30 years to
identify those individuals with FAP who may develop troublesome duodenal polyps..
The interval between procedures is determined by the number and type of polyps
found and can be anywhere between 1 -5 years.
What is the treatment?
Once large bowel polyps are found individuals
with FAP will be advised to have surgery to remove the large bowel.
Surgery is generally planned towards
the end of the teenage years, once schooling has been completed.
There are 2 main types of operation:
Colectomy and ileo-rectal anastomosis (IRA) involves
removing the large bowel and attaching the small bowel to the rectum or bottom
part of the large bowel. The remaining rectum
can still develop polyps so this must be examined every twelve months to identify
and remove these polyps in order to prevent
a cancer starting there. An individual
who has had a colectomy and IRA may need further surgery if an unmanageable number of rectal polyps
develop. This surgery involves removing the remaining bottom part of the bowel
and creating a new ‘back passage” as described below.
Sometimes at the age when the initial surgery is being
planned more extensive polyps have already developed in the rectum and colon
and therefore the planned surgery involves removing the whole rectum and colon.
This is called a pan procto-colectomy. A new “back passage” or ileal anal pouch
is created. The small bowel is fashioned
into a new rectum “pouch” and connected to the anus. This mean you can pass a
motion normally through your anus. Following pouch surgery regular endoscope
checks for polyps are required.
A pan procto-colectomy and ileo anal pouch may also be
planned as the initial surgery if desmoid disease is present in your family and
If it seems likely that desmoid disease will be present at the time of surgery.
This type of surgery is advised in this situation because desmoids can grow
after surgery and make further surgery more difficult.
An ileostomy is when the large bowel is removed and
the end of the small bowel is brought to the surface and the waste material is collected
in a disposable bag. Quite often after pouch surgery you do need an ileostomy for
a short time while the pouch heals. Your surgeon is best able to advise you as
to further details of these
Does diet matter?
At the moment there is no known
effect of diet on those with FAP. We
recommend a healthy diet and lifestyle. Healthy
foods include fruit, vegetables, cereals, bread (whole meal), pasta, rice,
olive oil and non-fat diary food such as yoghurt.
Possible harmful foods are excessive
amounts of animal fat, charred meat, beer and cigarettes.
For more information on diet Click Here
Is there medication available?
There
is evidence that the different types of Non Steroidal Anti-inflammatory Drugs
(NSAIDs) can decrease both the number and size of adenomatous polyps in the
large and small bowel. These drugs may at times be used to control polyp growth
while waiting for surgery. They are not routinely used because NSAIDs have a
range of side effects and the benefits of using these drugs has to be carefully
weighed up against the potential risk associated with their use.