FAQs on Bowel Cancer Screening

Dr John Martin answers some frequently asked questions about bowel cancer screening.

How does bowel cancer develop?

The majority of bowel cancers develop from small growths on the bowel wall called polyps. These are initially benign and begin when a colonic cell develops a genetic mutation that is normally the result of environmental factors, such as diet, or alternatively may be inherited from birth. The chance of developing a polyp increases with age and becomes a significant risk around the age of 45 years. Once present, approximately 1 in 10 polyps we will continue to acquire further mutations and increase in size to eventually become a colon cancer, and this process takes approximately 10 years.

How effective is bowel cancer screening?

The risk of developing colon cancer is around 1 in 18 for men and 1 in 20 for women. Colon cancer is the second commonest cause of cancer deaths within the UK. Removing benign colonic polyps before they become cancer is highly effective at preventing colon cancer and, with appropriate screening and follow-up, colon cancer should be totally preventable. In rare cases when a cancer is found at a screening investigation, this has a much greater chance of being curable than a cancer found in a patient who see a doctor because they have symptoms.

What is the rationale for bowel cancer screening?

The rationale for bowel cancer screening is dependent on the type of screening offered. In Population Screening the primary aim is to reduce deaths from colorectal cancer within a population. With Individual Screening, however, as offered at OneWelbeck, the aim is to prevent the development of colon cancer in an individual. Screening at OneWelbeck will reliably identify benign polyps, so that they can be removed before developing into a cancer. There will be a small number of individuals at which a cancer is found at the screening investigation, and these screening-detected cancers will normally have a very high chance of cure. For the significant majority of people, however, with appropriate follow-up, a cancer will never develop.

Does the NHS provide bowel cancer screening?

The NHS offers a highly effective colon cancer, population screening programme. Currently, (with regional variation), a stool kit is sent to all individuals registered with a GP every 2 years, beginning at the age of 56 years. If blood is detected in the stool (around 2 in 100 people), further investigation is offered. Despite finding a high number of large polyps or early cancers in those patients who have further investigation, the stool test is not sensitive at identifying small polyps and will also not identify some people with larger polyps or cancers. Although this programme confers a huge benefit to the population, a normal stool result does not definitively mean that any individual’s colon is normal, so they remain at some risk of having a cancer, or alternatively a polyp that may develop into a cancer in the future.

Is screening right for everyone?

Screening is appropriate for all people at average risk for developing a colon cancer, with the exception of certain individuals with significant serious health problems. Screening is not appropriate for patients at high risk for developing colon cancer, such as those with an inflammatory condition like Crohn’s disease or Ulcerative Colitis, patients with a genetic abnormality, such as a Lynch Syndrome, or those with a strong family history of colon cancer. These high-risk individuals should be under the care of a gastroenterologist to advise on their specific requirements for colon cancer surveillance.

What are the different tests available?

There are a variety of screening tests appropriate for population screening such as FIT, which detects the presence small quantities of blood in the stool that may not be visible, flexible sigmoidoscopy, a limited examination of the left colon, and molecular testing of stool to detect DNA abnormalities that predict the presence of polyps or cancer. The individual screening offered at OneWelbeck, however, provides investigations that, unlike those appropriate for population screening, will reliably identify the presence of polyps or cancer. Colonoscopy is the gold standard test for screening for colorectal cancer. It is highly sensitive for the identification of colon polyps and cancers, and benign lesions can be removed at the time of the initial investigation in most cases. An alternative is CT colonoscopy, which examines the colon with a specialised CT scan. This has the advantage of requiring a reduced bowel preparation regime, so is a little more convenient, but does, however, involve exposure to low dose radiation and is less sensitive than colonoscopy for the identification of small polyps. In addition, any polyps identified during this examination will require a colonoscopy to remove them.

What is the advantage of screening at OneWelbeck?

Colonoscopy at OneWelbeck is performed by highly experienced colonoscopists with a proven record of high quality, comfortable procedures and who have high detection rates for polyps. In addition, the ethos of the unit focuses on patient experience, and this is reflected in the pre-colonoscopy arrangements and unit environment, with all patients having their own private facility prior to and after the procedure. Anaesthetists are also available to ensure that the experience is as relaxing and comfortable as possible. CT colonoscopy is performed using high quality CT scanners and the images are reported by highly experienced gastrointestinal radiologists.

How often should I be screened?

The interval between screening examinations depends on the findings at the initial test. This may vary between 3 and 10 years, although more frequent procedures may be advised in certain patients with multiple polyps, or in whom large polyps have been removed.

Get in touch

If you would like to speak to one of our specialists about Bowel Cancer, or any other concerns you might have regarding your digestive health, please do not hesitate to get in touch with us today.

You can easily book online, or simply contact us through our online form or via telephone.

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Written by Dr John Martin

Dr Martin is the Director of the West London Bowel Cancer Screening centre and is an advisor to Public Health England on maintaining quality within the National Bowel Cancer Screening Programme. He is an expert in colorectal cancer screening with over 25 years of experience.