Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Bowel cancer is the fourth most commonly diagnosed cancer in the UK. Bowel cancers develop slowly from common bowel growths or polyps, so removing them can help prevent cancer. Screening with flexible sigmoidoscopy (also called ‘bowel scope’ or Flexi-scope) involves insertion of a thin flexible tube with a light and camera on the end into the bowel to examine the inner surface. Small bowel polyps can be removed during screening. The aim of the UK Flexible Sigmoidoscopy Screening Trial (UKFSST) was to determine whether having just one flexible sigmoidoscopy screen at around 60 years of age could prevent bowel cancer from developing and reduce the number of deaths from bowel cancer. The trial also aimed to determine how long any benefit lasts, and what is the best age to do the screening examination.

Who can participate?
Men and women who were aged 55–64 years and registered at a participating GP practice between November 1994 and March 1999.

What does the study involve?
The UKFSST was a randomised controlled trial. People who participated in the trial were randomly assigned to receive either flexible sigmoidoscopy screening or no screening (which was the usual care offered at the time of the trial).

What are the possible benefits and risks of participating?
Potential benefits of participating in the UKFSST included the possibility of being assigned to screening and having polyps detected and removed. Possible risks included adverse physical and psychological effects associated with the screening procedure and screening results. Individuals who participated in the trial but who were not assigned to screening received usual care and so were not worse off for having participated.

Where is the study run from?
The UKFSST recruited people from 506 GP practices that served 14 UK hospitals: 11 in England, two in Wales, and one in Scotland. Flexible sigmoidoscopy screening was done in endoscopy clinics at the hospitals.

When is the study starting and how long is it expected to run for?
Recruitment for the study and flexible sigmoidoscopy screening started in November 1994 and was completed in March 1999. The researchers have been following the participants since then, and will continue to follow them through 2024. The data will then be analysed and results written up, and the study will be completed by the 31st March 2027.

Who is funding the study?
National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (UK)

Who is the main contact?
Dr Amanda J Cross

Trial website

Contact information



Primary contact

Dr Amanda Cross


Contact details

Imperial College London
St. Mary's Campus
Norfolk Place
W2 1PG
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Multicentre randomised trial of 'once only' flexible sigmoidoscopy screening for prevention of bowel cancer morbidity and mortality



Study hypothesis

Primary aims:
1. To quantify the reduction in incidence and mortality
2. To determine the duration of efficacy of a single flexible sigmoidoscopy
3. To determine the optimum age for the examination
4. To evaluate health service research implications to permit an informed decision at the end of the trial about the suitability for implementation within a national screening programme

The criteria to be evaluated include:
1. Uptake, acceptability and impact
2. Quality control of the procedure
3. Cost-effectiveness

Ethics approval

South East MREC, ref: MREC/03/1/002

Study design

Randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting

GP practices

Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Colorectal cancer


'Once only' flexible sigmoidoscopy screening/control

Intervention type



Not Applicable

Drug names

Primary outcome measure

Incidence, mortality from colorectal cancer

Secondary outcome measures

Psychological morbidity, costs to the NHS

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

All 55-64 year old men and women from selected general practices

Participant type


Age group




Target number of participants

Recruitment closed after randomising over 170,000 people

Participant exclusion criteria

1. If incapable of providing informed consent
2. Patients with a personal or family history of bowel cancer (greater than two family members)
3. A recent sigmoidoscopy or colonoscopy
4. Severe illness or life expectancy of less than 5 years

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Imperial College London
W2 1PG
United Kingdom

Sponsor information


Medical Research Council (MRC) (UK)

Sponsor details

20 Park Crescent
United Kingdom
+44 (0)20 7636 5422

Sponsor type

Research council



Funder type

Research council

Funder name

Medical Research Council (MRC) (UK)

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

Publications of secondary endpoint analyses and further follow-up of the cohort are planned in high-impact peer reviewed journals between 2019 and 2028.

IPD sharing statement
The datasets generated during and/or analysed during the current study are not expected to be made available due to the terms and conditions of the data sharing agreements the researchers hold with third party data providers and their section 251 approval. However, anonymised, aggregated data may be made available upon application to the CSPRG: and

Intention to publish date


Participant level data

Not expected to be available

Basic results (scientific)

See additional file ISRCTN28352761_BasicResults_15Mar19.pdf

Publication list

2002 baseline results in:
2003 results in:
2010 results in:
2017 results in:
2018 results in:
2018 results in:

Publication citations

Additional files

Editorial Notes

26/03/2019: Publication and dissemination plan added. The basic results of this trial have been uploaded as an additional file. 22/03/2019: Publication reference and IPD sharing statement added. 15/02/2019: The following changes were made to the trial record: 1. Plain English summary and trial website added. 2. Contact details updated. 3. The overall trial end date was changed from 31/12/2015 to 31/03/2027. 4. Publication references added. 27/02/2017: Publication reference added. 28/02/2014: The following changes were made to the trial record: 1. The target number of participants field was changed from '195,000 - Recruitment ongoing' to 'Recruitment closed after randomising over 170,000 people'. 2. The overall trial end date was changed from 31/12/2010 to 31/12/2015.