Bowel cancer prevention - what you need to know ...
Watch our video about bowel cancer
screening
Bowel cancer is the third most common
cancer in the UK with 38,500 new cases every year. Around half of
these people will die, making it the second most common cause of
cancer death after lung cancer, but despite this, many of us have
no idea what the symptoms are.
Early diagnosis is vital because, if spotted
early, bowel cancer is one of the most treatable forms of cancers
(with over 90% of people surviving for 5 years or more if the
cancer is diagnosed in the early stages).
On average, there is approximately a 1/20 lifetime risk of
developing the disease. But it’s not all bad news! No other cancer
is as preventable and if caught early it can nearly always be
cured, sometimes even without the need for surgery. This article
answers your frequently asked questions about bowel cancer and
discusses the options for bowel cancer screening to limit the
impact of this common disease.
What are the symptoms of bowel cancer?
Early bowel cancer may give no symptoms at all. Some of the
classical symptoms, however, are:
-blood seen on or mixed in with stool or in the toilet pan
-a change in bowel habit - to more frequent bowel actions or
occasionally constipation
-tiredness or shortness of breath from anaemia due to blood loss
into the bowel
-abdominal pain (see below)
-weight loss
-a persistent lump in the abdomen
Abdominal pain in isolation is rarely due to bowel cancer and
many of the symptoms listed above are commonly due to less serious
benign conditions such as piles, diverticular disease or irritable
bowel syndrome. However new symptoms should always be discussed
with your GP who can advise on whether further investigation or
screening for bowel cancer is indicated.
Who is at risk?
The simplest answer to this question is everyone over the age of
50 years. Cancer is unusual before the age of 50, but younger
patients with symptoms should always be checked carefully as 7% of
colon cancers occur before 50, and a few at a very early age. Some
patients are at higher than average risk for bowel cancer so need
more regular check ups starting at an earlier age. These include
those with a family history of bowel cancer or polyps, those who
have had polyps previously and patients with total colitis who have
had their disease for 8 years or more. If in doubt discuss your
family history or personal disease history with your family doctor.
For those with a family history of colon and other cancers, advice
from a geneticist may be useful in estimating risk and establishing
an effective surveillance programme.
How does bowel cancer happen?
Nearly all bowel cancers start as polyps. These are small benign
growths, a bit like warts, on the inside of the bowel wall which
grow slowly. Eventually some polyps turn into cancers which can
then invade into the bowel wall and spread to other parts of the
body. The natural history of the development of bowel cancer means
it is ideal for a screening and cancer prevention programme because
most polyps develop into cancers very slowly over a 10-20 year time
period so there is a “window of opportunity” to find and remove
them and prevent cancer. Removing polyps reduces the risk of colon
cancer by about 80%.
Even if cancer has occurred, caught early (for example at Stage
A) it is nearly always curable. 85% of people treated at stage A
will survive the next 5 years, whereas if the diagnosis is made
late, at stage C, less than 50% will survive.
What can I do to reduce my risk of colon
cancer?
General health advice applies equally to bowel cancer
prevention:
-eat a balanced diet, reducing animal fat intake particularly
from red meat
-exercise to keep the heart and chest healthy reduces risk of
colon cancer
-keep your weight down
-above all don’t smoke
-have any symptoms checked out promptly
-have a screening procedure
What are the options for bowel cancer
screening?
1. Faecal Occult Blood test (FOBt)
This involves looking for blood in the faeces. The test kit is
simple, inexpensive and can be performed in the privacy of your own
home. Patients with positive tests (blood present) would normally
require a colonoscopy as 50% of people with persistently positive
tests will have large polyps or even cancer. The weakness of the
FOB test is that it not very sensitive or specific for cancer. Put
another way, many patients with cancer or large polyps don’t have
blood showing in the stool and are FOB test negative and many
patients who are positive for the test in fact have no colonic
problem.
2. Flexible sigmoidoscopy
This involves passing an endoscope (thin, flexible tube with a
miniature video camera on the end) through the anus to examine the
rectum and first part of the colon. It involves having a cleansing
enema prior to attending a hospital Endoscopy Unit for a quick,
5-10 minute, and usually painless examination. Polyps and cancers
detected can be biopsied. This test is highly sensitive and
specific for cancer or polyps in the part of the bowel that is
examined. However it only examines about 1/3 of the colon, so
cancers and polyps higher in the bowel can be missed
3. CT (virtual) colonography
This is a new technology which uses CT (x-ray) scanning to
examine the entire large bowel. It is a highly specialised
technique and therefore operator-dependent, so the choice of
hospital and radiologist is crucial. The test itself involves lying
in a scanner for a minute or two after air has been pumped into the
colon through a small tube inserted through the anus. It has the
advantages of screening the whole colon but usually requires full
bowel preparation (strong laxatives to empty out the bowel, taken
the day before) similar to colonoscopy and does involve exposure to
small doses of x-ray radiation. Early experience suggests that in
expert hands it is accurate for detecting cancers and most large
polyps although less so for polyps < 1cm in size. It is however
a purely diagnostic test and cannot remove or biopsy any polyps
seen. Positive findings at CT colonography would usually lead to
the need for a conventional colonoscopy to remove any polyps or
take biopsies from suspected cancer.
4. Colonoscopy
Colonoscopy is the gold standard examination for the large bowel
and is now widely established in the USA as the recommended bowel
cancer screening investigation. It involves inserting a long,
flexible endoscope all the way around the colon to directly
visualise all areas where polyps and cancer can occur. Again it is
critically dependent on the operator and the equipment. You would
need to take a full bowel preparation the day before colonoscopy so
that the colon is clean and views are optimised. If you are
constipated you may need more laxatives to cleanse the colon. The
procedure is carried out in the Endoscopy Unit and patients are
offered sedation if they want it, though at least 50% of people can
have colonoscopy without. The advantages of unsedated colonoscopy
are an immediate return to normal life and the avoidance of
unnecessary drugs.
Modern video endoscopes give high definition colour images which
are superior to looking directly at the bowel wall with the naked
eye. If polyps or cancer are detected they can be biopsied or
removed, so colonoscopy is definitive, combining diagnosis with
treatment in one procedure. Colonoscopy is highly sensitive and
specific for cancer and polyps but does carry a small risk of
complication, mainly from removing polyps or early cancers from the
bowel wall. It is also highly operator dependent, in that the
comfort, accuracy and risk of the procedure is directly related to
the skill and experience of the doctor performing it. At the London
Clinic all our endoscopists take part in a quality assurance
programme to demonstrate expertise.
Which is the best screening test for me?
In the USA bowel cancer screening by colonoscopy has been
established since 2000 with the recommendation that average-risk
individuals are screened every 10 years from age 50 by colonoscopy.
Incidence rates of bowel cancer in certain patient groups are now
falling in the USA suggesting that screening is having a positive
overall impact. Your GP can be a helpful source of advice and you
should discuss the tests and the choice of operator if you want to
be screened.
How can I know the doctor I will see is an expert at
colonoscopy?
Standards of colonoscopy do vary from centre to centre and from
doctor to doctor. In expert hands the procedure should be
comfortable, safe and complete and sedation can be kept to a
minimum which makes the procedure inherently safer and quicker.
Within the NHS there is now a process of accreditation of
colonoscopists to perform the procedure in the screening setting.
Doctors passing the accreditation test have a major focus on
colonoscopy in their working practices and have proved their
knowledge and hand-skills to their peers.
If you are having a colonoscopy don’t be afraid to ask the
doctor performing the procedure the following questions:
-How many colonoscopies have you performed in your career?
Most experts will have performed thousands of
examinations
-How many do you perform each week?
Most experts will be doing at least 10 a week
-How often do you get all the way around the colon?
This should be at least 90%
-Have you ever had any major complications and how often have
they occurred?
Perforation should be <1:5000
-Are you accredited to perform screening colonoscopy in the
NHS?
Bear in mind that not all competent colonoscopists are
involved in the NHS Bowel Cancer Screening
Programme, so this may be less important than the
other questions above
How can I find out more about bowel cancer screening at
The London Clinic?
We now have a patient telephone helpline, manned by one of our
specialist endoscopy nurses who can answer all your questions about
bowel cancer screening.
Information written by Dr. Peter
Fairclough and Dr.Brian Saunders both of
whom are Consultant Gastroenterologists and Colonoscopists
accredited by the National Bowel Cancer Screening
Programme
General Disclaimer
This page is designed for educational purposes only and is not
engaged in rendering medical advice or professional services. The
information provided through these pagess should not be used for
diagnosing or treating a health problem or a disease. It is not a
substitute for professional care. If you have or suspect you may
have a health problem, you should consult your health care
provider.