Colorectal Cancer – Choosing the Right Screening Test For You

This blog is written by our clinicians and aims to keep patients informed with up to date information on medical conditions. The editor of the blog is Dr Cristina Romete.

Colorectal cancer (commonly referred to as ‘bowel cancer’) rates are dropping significantly in the USA (by around 30%)1, however the average rate in the UK has been stable since the 1990s2.

What Are the Americans Doing That We Aren’t? The Answer Might Be in Their More Regular Use of Screening.

From annual home testing kits for bowel cancer to colonoscopies and sigmoidoscopies every 5 to 10 years, screening for colorectal cancer is more commonplace in the US.

Colorectal cancer

Colorectal cancer is one of the most common cancers, with 1 in 20 people likely to develop it at some point in their lifetime. Although it is typically a condition that affects older adults, cases in younger adults have risen by 33% in those aged 24-59 over the last 20 years in the UK.2

Colorectal cancer is much more likely to be curable if caught early. In fact, if caught early enough, 90% of these cancers are treatable and beatable.3

Who should undergo screening for bowel cancer?

In short…everyone.

But in particular, those at higher risk of bowel cancer, including individuals with4:

  • A personal history of colorectal cancer or adenomatous polyps;
  • A strong family history of colorectal cancer or polyps, such as cancer or polyps in a first-degree relative younger than 60 or in 2 first-degree relatives of any age. A first-degree relative is defined as a parent, sibling, or child;
  • A personal history of chronic inflammatory bowel disease (Crohn’s and Ulcerative Colitis);
  • A family history of any hereditary colorectal cancer syndrome, such as Familial Adenomatous Polyposis or Lynch Syndrome.

Screening test options

There are a number of screening tests that can be used to look for polyps (a frequent precursor of colorectal cancer) or colorectal cancer in people that have no symptoms and that are likely to be in the early stages of bowel cancer.

Below is a list of the options and at the bottom of the page is a table summarising all of the information.

Home testing kits

There are 2 commonly used types of home testing kits: Foecal Occult Blood Test (FOBT) and the Foecal Immunochemical Test (FIT). The FOBT test requires collection of 3 samples over a 2-week period, whilst the FIT test requires one sample only. FIT test has a better sensitivity, meaning is more likely to find a cancer than the FOBT test.

Both can be done at home by providing a stool sample and both look for the presence of blood in your stool, which can be an early sign of polyps or bowel cancer. The downside of the tests is that any non-bleeding cancers may not be detected.

The NHS offers a limited bowel cancer screening service using this method to the following groups:

  • England, Wales and Northern Ireland, People aged 60 to 74, every 2 years
  • Scotland, People aged 50-74, every 2 years
  • People aged 75 and over can ask for a home testing kit every 2 years

Scotland uses the FIT test whilst the other parts of UK use the FOBT test. Changes to FIT testing are expected during 2019 in England and Wales.

Privately, ROC recommends a FIT test over the FOBT one, and should be carried out annually.

A FIT-DNA test (stool DNA) is available in USA, and combines a FIT test with that detects altered DNA in the stool. It does require one to collect the entire bowel movement for analysis and is carried out once every 1-3 years. In UK, stool DNA kits may be purchased online.

Colonoscopy

This camera test is the best way of screening for colorectal cancer and has the added benefit of also being therapeutic at the same time. When the bowel is visualised, if any polyps or lesions are found – they can be biopsied or removed as necessary at the same time.

At ROC, we recommend colonoscopy as the gold standard method of bowel cancer screening, starting from the age of 40, every 10 years. If polyps are found, even if non-cancerrous at the time, it may be recommended you have a Colonoscopy every 3-5 years.

Sigmoidoscopy

In some parts of the UK, people aged 55 are already being invited for this screening test on the NHS5. It also uses a camera (much like the colonoscopy) however it does not inspect the whole length of your bowel, just the end third, leaving two thirds of the bowel unexamined.

If any polyps or abnormalities are found at this test, you are then referred onwards for a colonoscopy, which is the more complete investigation.

CT Colonography (virtual colonoscopy)

As interesting and less invasive as this test might sound, we do not recommend it for cancer screening. This test is carried out by inserting a small tube into the rectum and then a CT scan used to image the colon. It can miss small polyps and flat polyps; thus it is not a thorough enough investigation and not one that we recommend.

Colorectal cancer screening summary table

At ROC we have summarised the options available for colorectal cancer screening for you, including pros and cons in the table below.

If you have any questions about bowel cancer screening or our well-man/well-woman packages, send us an e-mail or call us and book an appointment with one of or GPs.

Investigation Pros Cons ROC’s recommendation
Home testing kits (FOBT) Non-invasive

Cheap.

Identifies only approximately 50% of the cancers.

Involves 3 sample collection over a 2-week period.

D  We do not recommend this test. If carried out should be undertaken annually.
Home testing kits (FIT) Non-invasive

Cheap.

Identifies only 75% of the cancers. C  We recommend this test be considered as a screening method annually from the age of 40, or earlier if indicated.
Colonoscopy Identifies 95% of the cancers.

Option of treatment/biopsy of polyps at the same time.

Invasive, requires preparation and cleaning of the bowel with a laxative.

Rare procedure complications; it is considered relatively safe

C  We recommend a colonoscopy is considered as a screening test starting age 40, every 10 years, earlier or more often if indicated. Colonoscopy is considered the Gold Standard Screening Test for bowel cancer.
Flexible sigmoidoscopy Sedation not usually required

Quick exam can be done in outpatients.

Abnormal areas may be biopsied at the same time.

Only examines the lower third of the colon.

You may need to return for a colonoscopy.

D  Not the best test available, so colonoscopy is typically recommended over this test. As a screening test should be considered every 3-5 years.
CT colonography/ Virtual Colonoscopy Relatively Low risk.

Cheaper than a Colonoscopy.

Visualises organs as well as the colon.

Requires Fasting and preparation.

Can miss smaller polyps.

Uses x-ray radiation.

If any abnormalities are found, you will need a colonoscopy.

D  Not recommended by ROC. This test is expensive and a colonoscopy is often recommended following this test. If undertaken as a screening test, should be done every 5 years.

 

 

References:

1) http://www.screenforcoloncancer.org/screeningoptions.asp

2) https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bowel-cancer/incidence#heading-Two

3) https://coloncancercoalition.org/get-educated/get-screened/colon-cancer-screening-options/

4) https://www.cancer.net/cancer-types/colorectal-cancer/screening

5) https://www.nhs.uk/conditions/bowel-cancer-screening/

 

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