Screening Why screen?
Screening is the broad term used to describe testing for bowel cancer or its precursor (polyps) before symptoms occur. Regular screening is important because bowel cancer can develop without any early warning signs. Bowel cancer can be treated successfully if detected in its early stages. There are a number of screening tools used, and your GP can help you determine the best method of screening for you based on your medical history.Cancer and polyps can develop on the inside lining of the bowel for a number of years, and often during this time, minute amounts of blood can leak from the growths, and present in the bowel motion.
What is a FOBtest?
A Faecal Occult Blood Test (FOBtest), is a simple, non-invasive screening test that you can do in the privacy of your own home, which can detect these small invisible quantities of blood in the bowel motion. Although no screening test is guaranteed to always be 100% accurate, the FOBtest is now widely accepted as being well researched, well trialled, least expensive and least invasive way to test for the early signs of bowel cancer. It is recommended that the FOBtest be completed at least once every 2 years.Regular screening of people over 50 using a FOBtest has the potential to significantly reduce the number of people who die from bowel cancer in Australia each year. It could even save your life. If you have a family history of bowel cancer, blood in your stool or any other symptoms, you should consult your doctor as soon as possible. For information on other forms of bowel cancer screening, please see below.
Where can I get a FOBtest?
The Federal Government’s current National Bowel Cancer Screening Program offers free faecal occult blood test (FOBtest) screening to people turning 50, 55 or 65 years of age between 1 January 2008 and 31 December 2010. These tests are sent out to eligible Australians.More information on the National Bowel Cancer Screening Program is available by phone on 1800 118 868 or visit www.cancerscreening.gov.au
Is a FOBtest effective for detecting bowel cancer?
Yes. The test available via this web site has demonstrated the highest sensitivity for bowel cancer detection of any non-invasive screening test: 89% sensitivity for cancer. The test has been shown to be very accurate. Clinical trials at two of the world’s leading clinical trial sites for bowel cancer screening have shown the test is very specific and sensitive, which means earlier detection for cancers. The National Health and Medical Research Council and Cancer Council recommend screening at least once every 2 years which can reduce the risk of mortality from bowel cancer by as much as 33%. 1-3 What is the difference between a 'guaiac' and 'immunochemical' FOBtest?
There are two types of FOBtests available - guaiac tests and immunochemical tests. When using a guaiac test, a person should not consume red meat, specific fruit and vegetables (for example, raw broccoli), vitamin C supplements, aspirin or anti-inflammatory drugs for three days prior to taking their first test sample and throughout the testing period. There are no restrictions on diet or medication for immunochemical FOBtests. An immunochemical test is being used in the National Bowel Cancer Screening Program. Why are two samples required to complete the FOBtest?
Two samples are required (from two separate bowel motions) because blood is not released constantly. Bleeding may occur only sometimes so it is important to provide two samples to ensure the best chance to pick up any potential problem. When should the test NOT be used?
You should NOT do the FOBtest (a simple screening test for bowel cancer):• If you see blood in the toilet bowl
• If you have any haemorrhoids that are actively bleeding.
• Three days before, during, or three days after your period.
You can perform the test if someone else in the house is menstruating, provided that you flush the toilet twice before beginning your sample collection process.
What if your FOBtest result is positive (blood found)?
If your test result is positive, you and your nominated doctor will receive a letter explaining that some blood was present in the samples you provided. There are many reasons why blood may be present, and most are not related cancer (eg bleeding from piles, menstruation, etc). In fact, in more than 90% of cases, people with blood in their stool have been found to be bowel-cancer-free. However, it is very important to ascertain the cause of the bleeding and if you see blood in your stool or receive a positive FOBtest (a simple screening test for bowel cancer) result, you should contact your doctor as soon as possible (within a fortnight) to discuss the result. In most cases, your doctor will refer you to a specialist for a colonoscopy. This procedure is the most accurate way of checking why blood was detected in your bowel motion. Keep in mind that bowel cancer is almost always curable if detected early enough, so please don’t hesitate to act on a positive result; consult your doctor. What if your FOBtest result is negative (no blood found)?
If no blood is detected in your faeces sample, you and your nominated doctor will receive a letter explaining that that you recorded a negative test. Not all bowel cancers bleed, and some may only bleed now and then, so a negative FOBtest result does not necessarily mean that you don’t have, or will never develop, bowel cancer. For this reason, it is highly recommended that you complete the test annually. After you submit your first FOBtest for analysis, you will subsequently be sent a reminder to retest every year. If you ever notice any sign of blood in your bowel motions, or have any symptoms of bowel cancer, it is reommended that you consult your doctor as soon as possible.Other tests
There are a number of screening methods available, which are used to identify whether bowel cancer is present, and your GP will determine the best method of screening for you.
- Rectal Examination
A simple test where the doctor inserts a gloved finger into the anus to feel for anything unusual in the lower part of the bowel.
- Barium Enema & X-ray
A small tube is inserted into the rectum and a liquid called barium is delivered. With air added, the barium is forced into the creases of the bowel wall and allows the bowel lining to be seen clearly when x-rays are taken. This method is less accurate than a colonoscopy as it can easily miss smaller cancers and polyps.
- CT scans and ultrasounds
The technique for constructing pictures from cross-sections of the body, by x-raying the part of the body to be examined from many angles. The use of soundwaves to build up a picture of internal parts of the body. Ultrasound can be used to measure the size and position of a tumour.
- Sigmoidoscopy
This test involves a rigid or flexible lighted telescope (sigmoidoscope) being inserted into the anus to examine the lining of the lower bowel.
- Colonoscopy
An examination using a flexible telescope passed into the bowel through the rectum, which enables the lining of the large bowel to be examined. Unlike x-rays, which take photographs, colonoscopy allows direct visual examination of the interior of the bowel and, in most instances, can provide substantially more detail and accuracy than an x-ray. Sometimes small samples (biopsies) are removed from the lining of the bowel so that they can be examined under a microscope to determine of there is any abnormality or pathology. In addition, if early growths called polyps are present in the bowel, they will usually be removed at the time of the colonoscopy.
Click here to read more about colonoscopy.
Click here to read more about polypectomy.
- Faecal Occult Blood Test (FOBTest)
Used to detect the presence of hidden blood in the faeces, which may be an indication of a polyp or a cancer. False negative and false positive results can occur.
- Virtual Colonoscopy
A new screening tool currently undergoing evaluation for accuracy and efficacy. The colon is inflated with air and a CT scanner image is taken. Virtual reality techniques construct a 3 dimensional image. If a polyp or growth is detected, a colonoscopy will be required to remove them.
Colonoscopy
What is a colonoscopy? A relatively safe and common day procedure, a colonoscopy is an internal examination of the lining of the colon and rectum (large bowel) using a special instrument called a colonoscope, which is slowly and carefully passed into the bowel through the back passage.
Essentially a long, flexible tube (about the thickness of a finger) with a light and a tiny video camera at one end, the colonoscope enables the specialist to see any unusual growths or inflammations, ulcers, polyps or bleeding, which might require further analysis.
The test requires special dietary preparation, is usually done in a hospital or day clinic, and generally takes between 20 to 60 minutes to complete.
If any inflammations or abnormalities are detected, a sample of tissue may be taken (using a special instrument passed through the colonoscope) and later sent for examination in a pathology laboratory.
It is important to remember that the taking of a biopsy does not necessarily mean you have bowel cancer, or that cancer is suspected. It is also vital to keep in mind that if the early signs of bowel cancer are detected and treated early, it can be prevented.
A colonoscope is also used to locate and remove polyps. To find out more, please see What is a polypectomy?
The colonoscopy is usually performed in a hospital or day clinic by a specialist, following referral from a doctor.
What preparation is required for a colonoscopy?
Your large bowel needs to be completely empty at the time of your colonoscopy, to make the colonoscopy easier and enable the specialist to gain a clear view of the bowel lining. Usually you will be provided with a ‘preparation kit’, which will include full instructions on how to prepare for your colonoscopy during the 48 hours prior to the procedure. The kit will also contain a special drink designed to help empty the bowel. Usually you will also be instructed to drink lots of clear liquid, take laxatives and refrain from solid food for up to 48 hours prior to the test. This preparation can be done at home.
In the six hours immediately prior to your colonoscopy, you must refrain from all food and drink (except for a sip of water with your regular medications).
You should tell you doctor well in advance of the test what regular medicines or vitamins you are taking, as some have the potential to cause complications. For example, most doctors advise you to stop taking aspirin and other blood-thinning medicines, certain arthritis treatments and iron pills at least seven days prior to your colonoscopy. Be sure to also tell you doctor if you have any of the following:
- A disease of the heart valve
- A pacemaker
- Diabetes
What happens during a colonoscopy?
If you have been given a sedative prior to your colonoscopy, you will probably sleep through most of it, although you might notice some aspects of the procedure, such as changes in position (for example, being moved by the medical staff from your left side to your back), temporary abdominal discomfort and inflation of the colon with air (dissention). The specialist examines the bowel as the colonoscope is inserted, and again when it is withdrawn. The procedure usually takes between 20 and 60 minutes. What happens after a colonoscopy?
You might feel a little groggy and bloated immediately after your colonoscopy, and you will usually be asked to rest for about two hours in a recovery area at the hospital or clinic. During this time the effects of your sedatives/anaesthetic will begin to wear off and you should pass most of the inflated air from you bowel. In some rare instances, you might pass a small amount of blood due to the biopsies that might have been taken, or the result of polyp removal during the procedure. After the two-hour recovery period you should be okay to go home. However, as there will still be some residual anaesthetic/sedatives in your system for a period, you should not drive, drink alcohol, travel alone on public transport, sign legal documents or operate machinery on the same day after the procedure, but instead arrange for a friend or relative to take you home and stay with you.
What is polypectomy?
A polypectomy
is a procedure to locate and remove polyps from
the bowel
using a colonoscope. Polyps are small growths on the bowel lining that are most
often benign,
but can sometimes contain a small area of cancer.
Polyps also have the potential to develop into bowel
cancer at a later stage. Polyps are removed using a specially designed wire that is passed down the colonoscope (avoiding the necessity for a major operation). The wire has a loop at the end that can be snared around the ‘stem’ of a polyp and charged with a painless electric current that cuts the polyp away from the bowel wall. The early removal of polyps stops them from becoming malignant, making it a key way to protect people from bowel cancer.
To view an image of a polyp click here
Are there any risks or complications from colonoscopy or polypectomy?
Colonoscopy and polypectomy are considered to be relatively safe procedures with a low risk of occasional complications. The colonoscope is thoroughly cleaned and surgically sterilised between patients to eliminate the risk of disease transmission. However, as with any procedure, complications can occur, and people should discuss the risks and benefits of colonoscopy with their medical practitioner before agreeing to undertake the procedure. Some of these potential complications can include the following…
- Localised, temporary irritation of the arm at the site of sedative injections
- Bleeding from the back passage as a result of a biopsy or polyp removal, which is usually minimal and will stop of its own accord, although occasionally bleeding might require cauterisation (via the colonoscope). Very rarely surgery or a blood transfusion might be required.
- While great care is always taken during the colonoscopy, very rarely a perforation of bowel wall can occur, which will necessitate abdominal surgery to rectify the tear.
- An adverse reaction to the sedatives or anaesthetic – of particular concern for people with severe lung or heart problems.
- An adverse reaction to the bowel preparation resulting in headaches, vomiting or dizziness.
- As with any surgical procedure involving anaesthetic, death is a very remote possibility.
In the hours and days after a colonoscopy you should immediately tell your doctor or specialist if you are experiencing persistent bleeding from the back passage, fever, strong abdominal pain, black motions or any other side effects that concern you.
What happens if bowel cancer is detected?
If bowel cancer is discovered during your colonoscopy, surgery will usually be required to remove it. It’s important to know that if bowel cancer is discovered at an early stage of development, you have an excellent chance of making a complete recovery. What if the colonoscopy doesn’t show anything?
A clear colonoscopy generally means that no polyps or cancerous growths were detected. This means that there is a low risk of developing bowel cancer within the next 10 years. However, it should be noted that while a colonoscopy is considered to be the most accurate test of the colon, no test is 100% accurate and there is a risk that an abnormality may not be detected. So even if you’ve had an ‘all clear’ we recommend that you still complete an annual FOBtest (a simple screening test for bowel cancer). If you develop any symptoms of bowel cancer at any time, even after a clear colonoscopy, you should consult your doctor as soon as possible.
references
References: 1. Mandel JS, Bond JH, Church TR et al. Reducing mortality from bowel cancer by screening for faecal occult blood. Minnesota Colon Cancer Control Study. N Engl J Med. 1993;328:1365-1371.2. Hardcastle JD, Chamberlain JO, Robinson MH, et al. Randomised controlled trial of faecal-occult-blood screening for bowel cancer. Lancet. 1996;348:1472-1477. 3. Kronborg O, Fenger C, Olsen J, et al. Randomised study of screening for bowel cancer with faecal-occult-blood test. Lancet. 1996;348:1467-1471.