UK Flexible Sigmoidoscopy Screening Trial (UKFSST)


UK Flexible Sigmoidoscopy Screening Trial

The UK Flexible Sigmoidoscopy Screening Trial (UKFSST) started in 1994 and is still on-going. The trial has received funding from a number of government and charitable sources including:

The UKFSST is a major research study and recruited over 170,000 people from across the UK. The first results assessing the effectiveness of the screening tested in this trial were published in 2010. The results confirmed that the test was very effective at preventing bowel cancer and very long-lasting. This study led directly to the introduction of flexible sigmoidoscopy (bowel scope/Flexi-scope) screening in the NHS English Bowel Cancer Screening Programme.

Harpal Kumar, Chief Executive of Cancer Research UK said of the UKFSST:
Cancer Research UK does not often use the word ‘breakthrough’ but this is one of those rare occasions when I am going to. It is extremely rare to see the results of a clinical trial which are quite as compelling as this. Flexi-scope needs to be brought in as soon as possible. Every week of delay will risk scores of lives.

On 4th October 2010, David Cameron announced that Flexi-scope is to be included in the NHS Bowel Screening Programme.

The trial is registered with the ISRCTN registry. Its unique number is 28352761.

Our Data Protection and Privacy Notice

Privacy Notice

In order to conduct our research Imperial College London is the data controller for personal information from health care records (also known as ‘special category’ data). We either obtain this data directly from NHS Trusts or via third parties such as NHS Digital, the Office for National Statistics, National Cancer Registries (including the Welsh Cancer Intelligence and Surveillance Unit) and Information Services Division Scotland, part of NHS National Services Scotland This means that we are responsible for looking after your information and using it properly. The CSPRG intends to keep special category, personal data for 10 years after our studies finish, as per the Imperial College London data retention guidelines. Imperial College London, UK, is the sponsor for our studies.

Further information on Imperial College London’s retention periods may be found at

A link to Imperial College London’s data protection webpage may be found at The CSPRG privacy notice, described here, is most applicable to the information provided by CSPRG study participants and therefore takes precedence.

Your rights / GDPR Individual Rights

Your usual statutory rights to access, change or move your information are limited, because of exceptions applicable to some types of research, and also because we need to manage your information in specific, lawful ways in order for the research to be reliable and accurate. To safeguard your rights, we will use the minimum personally-identifiable information possible.

The EU General Data Protection Regulation (GDPR) grants individuals several rights concerning their data:

  • The right to object (to processing of the data)
  • The right to correct (inaccurate or incomplete data)
  • The right to erasure (also known as “the right to be forgotten”)
  • The right to restrict processing (e.g. while the accuracy of the data is contested)
  • The right to portability (to have a copy of any data you have provided to us)
  • The right to access (to have a copy of data we hold about you)
  • The right to withdraw consent (if you have previously consented to take part)

If you think that we might be processing your data and you wish to exercise any of the rights listed above, please get in touch using the details on the Contact Us page.  Though it may not always be possible for us to fulfil your request, we will respond to your query within one month.  For more information on your GDPR rights, please see guidance provided by Information Commissioners Office.

Legal Basis

As a University we use personal data and special categories of personal data to conduct research to improve health, care and services. As a publicly-funded organisation, we must ensure that it is in the public interest when we use personal data and special categories of personal data.  Some of this data is from patients who have completed a consent form.  Where consent could not be sought, approval for obtaining and processing data was provided under section 251 of the National Health Service Act 2006.

Health and care research should be in the public interest, which means that we must demonstrate that our research serves the interests of society. We do this by following the UK Policy Framework for Health and Social Care Research.

Contact us

If you wish to raise a complaint on how we have handled your personal data or if you want to find out more about how we use your information, please contact Imperial College London’s Data Protection Officer via email at, via telephone on 020 7594 3502 or via post at Imperial College London, Data Protection Officer, Faculty Building Level 4, London SW7 2AZ.

If you are not satisfied with our response or believe we are processing your personal data in a way that is not lawful you can complain to the Information Commissioner’s Office (ICO). The ICO does recommend that you seek to resolve matters with the data controller (us) first before involving the regulator.

Privacy and data protection information relating specifically to the UKFSST study

The CSPRG has collected and will continue to collect information about the study participants of the UK Flexible Sigmoidoscopy Screening Trial (UKFSST) from NHS Digital, the Office for National Statistics, Public Health England, NHS National Services Scotland, and the Welsh Cancer Intelligence and Surveillance Unit and from the 14 participating study hospitals in England, Wales and Scotland. Study participants also completed a number of questionnaires about their health and experience of the flexible sigmoidoscopy examination. This information includes name, address, date of birth, NHS number, and health information, which is special category of information. We will use this information to determine whether having a once-only flexible sigmoidoscopy screening test at around age 60 years is effective at preventing bowel cancer and could reduce the number of deaths from this disease. The trial also aims to determine how long the benefit of the test lasts and the best age for it to be done.

What were the aims of the UKFSST?

The trial aimed to determine whether having a once-only flexible sigmoidoscopy screening test at around age 60 years was effective at preventing bowel cancer and could reduce the number of deaths from this disease. The trial also aimed to determine how long the benefit of the test lasted and the best age for it to be done.

What type of study was the UKFSST?

The UKFSST was a randomised-controlled trial. People who participated in the trial were assigned randomly to receive either flexible sigmoidoscopy screening or the usual care that was offered at the time of the trial, which was no screening. Well-designed randomised controlled studies, such as the UKFSST, are considered to provide the best evidence for whether a new treatment works effectively.

What is the flexible sigmoidoscopy (bowel scope, Flexi-scope) test?

During flexible sigmidoscopy (also called ‘bowel scope’ or Flexi-scope), a narrow, flexible tube with a camera on the end is inserted into the rectum and up into the lower part of the large bowel by a specialist nurse or doctor. Flexible sigmoidoscopy is used to examine the inner surface of the lower bowel for growths, called polyps or adenomas. Polyps are common and are not cancerous, but some can develop into cancer so they are generally removed as part of the procedure, or during a follow up test.

When and where did the study take place?

The UKFSST study recruited people from 506 participating GP practices based in 14 UK centres: 11 in England, two in Wales, and one in Scotland. Recruitment and screening started in November 1994 and were completed in March 1999.

The map below shows the geographical locations of the 14 UK centres that took part in the UKFSST study.


Who is included in the study?

375,744 men and women who were assessed for eligibility for the UKFSST trial included:

  • were registered at a participating GP practice between November 1994 and March 1999; and
  • were aged 55–64 years between November 1994 and March 1999

Of these, 170,432 people indicated in the study questionnaire or letter sent between September 1994 and March 1999 that they would take up the offer of screening if invited; and were assessed as being eligible for the study; and were randomised. 40,674 of these 170,432 people were screened.

The remaining 205,312 men and women included those who were sent a study questionnaire or letter between September 1994 and March 1999 asking whether they would take up the offer of screening if invited and

  • indicated that they would take up the offer of screening if invited and were eligible for the study but were not randomised as 40,000 people had already been screened (funding was given to screen 40,000 people); or
  • indicated that they would take up the offer of screening if invited, but were subsequently assessed as not eligible for the study; or
  • did not respond to the study questionnaire or letter; or
  • responded to the study questionnaire or letter that they would not take up the offer of screening if invited.

What type of information does the CSPRG hold for the purposes of the UKFSST?

The CSPRG holds the following personal information for the purposes of the UKFSST, which covers:

  • patient data– name, address, date of birth, NHS number, GP for all individuals in the age range 55-64 years between November 1994 and March 1999 belonging to participating general practices;
  • questionnaire data – including responses to various questionnaires sent at different stages of the study, family history of bowel cancer, symptoms, previous examinations and diet and smoking habits;
  • clinical information – including medical data collected prior to screening, details of symptoms, results of any medical tests or procedures and blood samples;
  • cancer diagnoses (for randomised patients) including histological diagnosis and stage of the disease;
  • Records of the deaths of individuals in the age range 55-64 years between November 1994 and March 1999 belonging to participating general practices.

We require the information that we hold in order to answer our research questions and to guarantee the quality and integrity of our results. It will not be possible to identify individuals from the published results of this study.

We have not finished collecting the cancer and death data we need and will continue to do so until March 2027. Our Patient Data  section provides further details on what information we hold for the purposes of our research, and how we use and protect this information.

What approvals has this study received?

Everyone who received a flexible sigmoidoscopy as part of the UKFSST gave their consent for this procedure (40,674 people).

Consent was not sought from people who received no further contact other than the initial questionnaire as the group in question was extremely large (335,070 people) and it was not possible to ask for consent from each individual.  We received permission to conduct this research study from the independent ethical review committees and organisations responsible for the data of NHS patients, including:

  • local research ethics committees in each of the 14 centres and the South-East multicentre research ethics committee;
  • Section 251 approval from the Patient Information Advisory Group (PIAG – a predecessor of both the National Information Governance Board/NIGB and the Confidentiality Advisory Group) in England, and an equivalent panel in Scotland, the Privacy Advisory Committee (now the Public Benefit and Privacy Panel for Health and Social Care) of National Services Scotland (NSS);
  • Research and Development approval from the NHS Trusts managing the centres involved in the trial;
  • approval from the Caldicott Guardian of the North West London NHS Trust;
  • approval from the UK Cancer Registries, NHS Digital, NHS Central Register (NHSCR), and the Office for National Statistics (ONS).

Why do we need to hold identifiable data for this study?

We need identifiable data to enable our data providers (such as NHS Digital, NHSCR, NSS, ONS, Cancer Registries and hospitals) to identify the study participants and provide us with follow-up data on cancers/deaths. We hold this data in the public interest (GDPR/DPA 2018: Article 6(1)e) for scientific research (GDPR/DPA 2018: Article 9(2)j)- please see the privacy notice for more information.

How long will we retain the data?

Our original funding allowed us to collect follow-up information on cancers and deaths for the UKFSST until March 2017. We have now been awarded additional funding to continue to follow-up the UKFSST cohort for a further 10 years until March 2027, until all the participants have reached the age of 80 years. Imperial College London, the organisation responsible for this study, requires that we hold data from all clinical studies for 10 years after the study end date. We therefore currently plan to hold the data for this study until March 2037.

What were the results of the study and what impact have they had?

When the first results of the UKFSST were analysed in 2010, they showed that people who were screened just once with flexible sigmoidoscopy (also known as bowel-scope) were:

  • less likely to get bowel cancer – it prevented about one in three new cases of bowel cancer;
  • less likely to die from the disease – it prevented four in every 10 deaths from bowel cancer.

The protective effects of the once-only flexible sigmoidoscopy also appeared to be long lasting. The UKFSST results were published in The Lancet in 2010.

Because the UKFSST demonstrated that flexible sigmoidoscopy screening can prevent bowel cancer from developing, this suggested that offering a once-only flexible sigmoidoscopy (bowel-scope) screening test to people in the UK should reduce the numbers of people getting bowel cancer and dying from this disease. In 2010, the UK government announced a £60 million investment to introduce bowel scope screening as part of the English NHS Bowel Cancer Screening Programme. Roll-out of bowel-scope screening began in 2013 and is expected to cover the entire population by 2018. It has been estimated that bowel-scope screening could prevent up to 5,000 people from getting bowel cancer and up to 3,000 deaths from the disease in the UK each year. It is hoped that cancer of the rectum, the lowest part of the bowel examined, could one day become a rare disease.

The results of a further 7 years of follow-up were published in The Lancet in Feb 2017 and show that a single flexible sigmoidoscopy continues to provide substantial protection from bowel cancer diagnosis and death, with protection lasting at least 17 years. Cancer Research UK and Imperial College London also published news articles.

In  addition to the original study objectives, the UKFSST study team has identified the following potential questions  which could be addressed by further analysis of the UKFSST dataset. These analyses will be conducted by the CSPRG medical statisticians and published in peer reviewed journals. No additional data will be requested to meet these objectives.

  • Does the quality of flexible sigmoidoscopy screening affect the future risk of getting bowel cancer and dying from this disease?
  • Does patient experience and procedural factors affect the performance of flexible sigmoidoscopy screening?
  • How safe and acceptable is a once-only flexible sigmoidoscopy?
  • How does having a family history of bowel cancer effect the risk of developing this disease after screening?
  • Can the severity of disease at diagnosis be used to determine the risk of dying from bowel cancer?
  • Among patients identified as higher-risk at their flexible sigmoidoscopy screening, how effective is repeated colonoscopy (examination of the entire bowel) at routine intervals?
  • How commonly does bowel cancer in the upper part of the bowel develop after flexible sigmoidoscopy, and can this be predicted by the number and type of polyp detected at flexible sigmoidoscopy?
  • Does smoking history affect the risk of developing polyps and bowel cancer?
  • Can various medications affect the risk of developing polyps and bowel cancer?
  • Among patients taking part in the UKFSST and also invited to take part in the National Bowel Cancer Screening Programme (BCSP), for which they complete Faecal Occult Blood Tests (FOBTs), how do these two screening tests affect the risk of getting bowel cancer?
  • Can prior flexible sigmoidoscopy affect participation and outcomes of FOBTs in the BCSP?


Pinsky PF*, Loberg M, Senore C, Wooldrage K, Atkin W, Bretthauer M, Cross AJ, Hoff G, Holme O, Kalager M, Segnan N, Schoen RE. Number of Adenomas Removed and Colorectal Cancers Prevented in Randomized Trials of Flexible Sigmoidoscopy Screening. Gastroenterology. 2018 Jun 20. pii: S0016-5085(18)34667-5. doi: 10.1053/j.gastro.2018.06.040.

Brown JP*, Wooldrage K, Kralj-Hans I, Wright S, Cross AJ, Atkin WS. Effect of once-only flexible sigmoidoscopy screening on the outcomes of subsequent faecal occult blood test screening. J Med Screen. 2018 Oct 3:969141318785654. doi: 10.1177/0969141318785654.

Atkin W, Wooldrage K, Parkin DM, et al. Long term effects of once-only flexible sigmoidoscopy screening after 17 years of follow-up: the UK Flexible Sigmoidoscopy Screening randomised controlled trial. Lancet. 2017 Apr 1; 389 (10076): 1299-1311.

McGregor LM, Bonello B, Kerrison RS, et al. Uptake of Bowel Scope (Flexible Sigmoidoscopy) Screening in the English National Programme: the first 14 months. J Med Screen. 2016 Jun;23(2):77-82.

Robb KA, Lo SH, Power E, et al. Patient-reported outcomes following flexible sigmoidoscopy screening for colorectal cancer in a demonstration screening programme in the UK. J Med Screen 2013: 1–6.

Robb K, Power E, Kralj-Hans I, et al. Flexible sigmoidoscopy screening for colorectal cancer: Uptake in a population-based pilot programme. Journal of Medical Screening. 2010;17(2):75-8.

Atkin WS, Edwards R, Kralj-Hans I, et al. Once-only flexible sigmoidoscopy screening in prevention of colorectal cancer: a multicentre randomised controlled trial. Lancet. 2010; 375: 1624–33.

Austin KL, Power E, Solarin I, et al.  Perceived barriers to flexible sigmoidoscopy screening for colorectal cancer among UK ethnic minority groups: a qualitative study. J Med Screen 2009; 16: 174–179.

Miles A, Atkin WS, Kralj-Hans I, et al. The psychological impact of being offered surveillance colonoscopy following attendance at colorectal screening using flexible sigmoidoscopy. J Med Screen 2009; 16(3): 124-130.

Robb KA, Power E, Atkin W, et al. Ethnic differences in participation in flexible sigmoidoscopy screening in the UK.  J Med Screen 2008; 15: 130-136.

Thompson MR, Flashman KG, Wooldrage K, et al. Flexible sigmoidoscopy and whole colonic imaging in the diagnosis of cancer in patients with colorectal symptoms. Br J Surg. 2008; 95: 1140-1146.

Brotherstone H, Vance M, Edwards R, et al. Uptake of population based flexible sigmoidoscopy screening: a nurse-led feasibility study.  J Med Screen 2007;14:76-80.

Mitrou PN, Loktionov A, Atkin W, et al. MTHFR C677T and A1298C polymorphisms and risk of colorectal adenoma in the UK Flexible Sigmoidoscopy Trial. (United Kingdom). Cancer causes control. 2006 Aug;17(6):793-801.

Thomas-Gibson S, Rogers, PA, Cooper S, et al. Judgement of quality of bowel preparation at screening flexible sigmoidoscopy is associated with variability in adenoma detection rates. Endoscopy. 2006;38:456-60.

Gunter MJ, Watson MA, Loktionov AS, et al. No association between cytochrome P450 and Glutathione S-Transferase gene polymorphisms and risk of colorectal adenoma: results from the UK flexible sigmoidoscopy screening trial. Cancer Epidemiology Biomarkers Prev. 2005;14(4):1028-30.

Atkin WS, Rogers P, Cardwell C, et al. Wide variation in adenoma detection rates at screening flexible sigmoidoscopy. Gastroenterology 2004;126:1247-56.

Miles A, Wardle J, Atkin W. Receiving a screen-detected diagnosis of cancer: the experience of participants in the UK flexible sigmoidoscopy trial. Psycho Oncology. 2003;12:784-802.

Adams C, Atkin WS, Cardwell C, et al. Effect of hysterectomy status on polyp detection rates at screening flexible sigmoidoscopy. Gastrointest Endosc. 2003;57(7):848-53.

Whynes DK,Frew EJ, Atkin WS. The costs of flexible sigmoidoscopy screening for colorectal cancer. Int J Technol  Assess Health Care. 2003;19(2):384-95.

Atkin WS, Cook C, Cuzick J, et al. Single flexible sigmoidoscopy screening to prevent colorectal cancer; baseline findings of a UK multicentre randomised trial. Lancet. 2002;359:1291-300.

Atkin WS, Edwards R, Wardle J, et al. Design of a multicentre randomised trial to evaluate flexible sigmoidoscopy in colorectal cancer screening. J Med Screen. 2001; 8:137-44.

McCaffery K, Borrill J, Williamson S, et al. Declining the offer of flexible sigmoidoscopy screening for bowel cancer: a qualitative investigation of the decision-making process. Soc Sci Med. 2001;53:679-91.

Wardle J, Sutton S, Williamson S, et al. Psychosocial influences on older adults interest in participating in bowel cancer screening. Prev Med. 2000;31:323-34.

Sutton S, Wardle J, Taylor T, et al. Predictors of attendance in the UK flexible sigmoidoscopy screening trial. J Med Screen. 2000;7:99-104.

Martin JP, Sexton BF, Saunders BP, et al. Inhaled patient-administered nitrous oxide/oxygen mixture does not impair driving ability when used as analgesia during screening flexible sigmoidoscopy. Gastrointest Endosc. 2000;51:701-3.

Taylor T, Williamson S, Wardle J, et al.  Acceptability of flexible sigmoidoscopy screening in older adults in the UK. J Med Screen. 2000;7:38-45.

Atkin WS, Hart A, Edwards R, et al. Single blind, randomised trial of efficacy and acceptability of oral picolax versus self-administered phosphate enema in bowel preparation for flexible sigmoidoscopy screening. Br Med J. 2000;320:1504-9.

Bell GD, Atkin WS, Painter J, et al. Increasing the reach of flexible sigmoidoscopy. Endoscopy. 1999;31:835.

Frew E, Wolstenholme JL, Atkin WS, et al. Estimating time and travel costs incurred in clinic-based screening: flexible sigmoidoscopy screening for colorectal cancer. J Med Screen. 1999;6:119-23.

Wardle J, Taylor T, Sutton S, et al. Does publicity about cancer screening raise fear of cancer? Randomised trial of the psychological effect of information about cancer screening.  Br Med J. 1999;319:1037-8.

Hart AR, Kudo S, Mackay EH, et al. Flat adenomas exist in asymptomatic people: important implications for colorectal cancer screening programmes. Gut. 1998;43:229-31.

Atkin WS, Hart A, Edwards R, et al. Uptake, yield of neoplasia and adverse effects of flexible sigmoidoscopy. Gut. 1998;42:560-5.

Atkin W. Flexible sigmoidoscopy as a mass screening tool. Euro J Gastroenterol Hepatol. 1998;10:219-23.