Bowel (colorectal) cancer is common. The outlook (prognosis) and chance of cure are much better if this cancer is detected at an early stage rather than at a later stage. A screening programme operates in the UK for certain age groups. The aim is to offer an easy screening test to detect bowel cancer when it is at an early stage and before symptoms start. Some people outside the normal screening age who have a high risk of developing bowel cancer are offered extra screening tests.
What is bowel (colorectal) cancer screening?
Screening means looking for early signs of a particular disease in otherwise healthy people who do not have any symptoms. If certain diseases are picked up early, the disease can be cured. Bowel cancer screening aims to detect bowel cancer at an early stage when there is a good chance that treatment will cure the cancer. There are two methods of screening for bowel cancer:
- A test to detect traces of blood in your stools (faeces). This is called either the faecal occult blood (FOB) test or the new faecal immunochemical test (FIT).
- An examination of the inside of the bowel by a test called flexible sigmoidoscopy.
Bowel cancer screening age
The NHS bowel cancer screening programme in England is offered to people aged 55 or over, as there is a higher risk of bowel cancer with increasing age:
- If you're between 60 and 74 years, you'll automatically be invited to use a home testing kit for an FOB test every two years.
- In most but not yet all areas, anyone aged 55 is invited for a one-off screening with flexible sigmoidoscopy.
- If you're aged 75 or over, you can ask for a home FOB testing kit every two years by calling the bowel cancer screening helpline on 0800 707 60 60.
However, bowel cancer screening is changing in England. An independent expert screening committee has recommended that bowel cancer screening in England should in future start 10 years earlier at age 50. The committee has looked at all the evidence in detail and have recommended that screening should be offered from age 50 to 74 using the faecal immunochemical test (FIT) - a home test kit. FIT is a new test due to be introduced into the screening programme in the autumn. Initially it will be offered every two years to men and women at the current age range of 60 to 74 - see below. This test is easier to use than the current test and is more accurate in detecting potential cancers.
The current bowel screening programme has a complementary procedure, flexible sigmoidoscopy (or bowel scope), which is a one-off test offered to men and women at 55. The committee recommends continuing with bowel scope screening in England, where it is currently rolled out, until FIT is offered to the same age group.
The American Cancer Society recommends that people who do not have an increased risk of colon cancer start regular screening at age 45. This can be done either with a stool-based test, or with a test that looks at the colon and rectum - bowel scope. People who are in good health with a life expectancy of more than 10 years should continue regular colorectal cancer screening through the age of 75. Between 76 and 85 years, the decision to be screened should be based on a person's preferences, life expectancy, overall health, and prior screening history. People over 85 should no longer get colorectal cancer screening.
Bowel cancer screening kits
Faecal immunochemical home test
The FIT kit consists of a small plastic container with a stick attached to the lid. People collect samples using the following steps.
- Scrape the tip of the stick along the bowel motion.
- Put the stick back into the bottle.
- Click the bottle shut.
- Put the used kit into the return freepost packaging and send for analysis.
You will get one of two screening results. These are:
- Normal result: no significant level of blood detected.
- Abnormal result: blood detected and the individual is offered an appointment to discuss having a colonoscopy.
Results will be sent to participants within two weeks of the kit arriving for analysis. Your GP will be notified of all test results.
Faecal occult blood test
Small (unnoticeable) amounts of blood in the stools (faeces) are common in people with bowel cancer. The test involves testing the faeces for hidden (occult) blood. See also the separate leaflet called Faecal Occult Blood Test.
If the FOB test is positive you will then be referred for further investigation which is usually a colonoscopy. A colonoscopy is a test in which a long, thin, flexible telescope (a colonoscope) is passed through your back passage (rectum) into your large bowel (colon). In this way the whole of your colon and rectum can be looked at in detail. An alternative to colonoscopy is a CT colonography.
There are various reasons other than bowel cancer for having a positive test. For example, some medical conditions including piles (haemorrhoids) can lead to a positive test. Most people with a positive test will NOT have bowel cancer.
Bowel cancer screening can also detect growths (polyps) on the inner lining of the bowel. These are not cancers but may develop into cancers over time. They can easily be removed, which makes it less likely that bowel cancer will develop.
Following a colonoscopy after screening:
- About 5 in 10 people who have a colonoscopy will have a normal result.
- About 4 in 10 will be found to have a polyp, which if removed may prevent bowel cancer from developing.
- About 1 in 10 people will be found to have bowel cancer.
Note: a normal test result does not completely rule out bowel cancer. It is therefore important to be aware of the symptoms of bowel cancer and to see your doctor if you are concerned.
Screening with flexible sigmoidoscopy
What is flexible sigmoidoscopy?
The sigmoid colon is the final portion of the large bowel (colon) which is joined to the back passage (rectum). A flexible sigmoidoscope is a small bendy tube with an attached light source, about the thickness of a pen. See also the separate leaflet called Sigmoidoscopy.
What is screening with flexible sigmoidoscopy?
It has been proposed that a routine flexible sigmoidoscopy test should be offered to all adults around the age of 55. This is because most bowel polyps and bowel cancers develop in the rectum, sigmoid colon or lower descending colon. Bowel (colonic) polyps are small non-cancerous (benign) growths on the inside lining of the colon or rectum. They get more common as we become older. They usually cause no symptoms or problems. However, if a polyp is found, it is usually removed. This is because there is a small risk of a colonic polyp developing into a bowel cancer after several years.
The results of a large UK research study were published in 2010. The study found that people who had one routine flexible sigmoidoscopy, between the ages of 55 and 64, had a reduced risk of developing bowel cancer by about a third. This was because any polyps that were found during the test were removed. Also, the test can detect early bowel cancers that have not yet caused symptoms.
In October 2010 the Government announced that £60 million would be spent to fund a new flexible sigmoidoscopy screening programme for people in England aged over 55 years. This is currently in a trial (pilot) stage in certain screening centres in England. If it is shown to be effective, this screening test will probably become available everywhere in the UK. It is thought that, combined with the existing FOB test, a one-off flexible sigmoidoscopy at around the age of 55-60 could dramatically increase the number of lives saved from bowel cancer.
Screening tests for younger people with increased risk
Some people have a higher than normal risk of developing bowel cancer. This is because some diseases cause an increased risk of developing bowel cancer. Also, relatives of people with certain diseases have an increased risk of developing bowel cancer. Therefore, some people are offered regular screening tests, often from a young age. The tests done are different from the regular screening programme. These groups of people offered extra screening tests include:
- People with certain inherited conditions. These are rare conditions. They include:
- Familial adenomatous polyposis (FAP).
- Hereditary non-polyposis bowel cancer (HNPCC).
- Peutz-Jeghers syndrome.
- Juvenile polyposis syndrome.
- Close relatives of people with FAP or HNPCC.
- People with a strong family history of first-degree relatives (mother, father, brother, sister, child) who have had bowel cancer. In particular, if the cancer developed in a close relative under the age of 45 years.
- People with ulcerative colitis or Crohn's disease affecting the large bowel (colon) or back passage (rectum).
- People with a condition called acromegaly.
- People who have had one or more bowel growths (polyps) removed.
- People who have had bowel cancer in the past.
The age at which screening starts, the type of tests offered and the frequency of the tests depend on the level of increased risk. The different diseases and family associations mentioned above have varying levels of risk. The tests may include regular colonoscopy or some specialised scans.
If you have a disease or family history that causes an increased risk of developing bowel cancer, your doctor will advise on the type of tests recommended and their frequency. The British Society of Gastroenterology guidelines in 'Further Reading and References' below may also be of interest.
Further reading and references
; American Cancer Society (May 2018)
; British Society of Gastroenterology (May 2010)
; NICE Clinical Guideline (March 2011)
; Press release Public Health England, 2018
; Cancer Research UK
; Colorectal Cancer Screening - Who, How, and When? Clin Endosc. 2018 Jan51(1):37-49. doi: 10.5946/ce.2017.141. Epub 2018 Jan 31.
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