ASCEND study

The ASCEND study involved 750,000 people who were invited to take part in the NHS Bowel Cancer Screening Programme in England. This project was led by Professor Rosalind Raine (University College London, UCL), and involved a collaboration between the NHS Bowel Cancer Screening Programme, the Health Behaviour Research Centre (UCL), the Centre for Cancer Screening (Queen Mary University of London) and the CSPRG (Imperial College London). We hope that the results will be used to inform the NHS Bowel Cancer Screening Programme on how best to invite people for screening in the future and to improve the effectiveness of the programme. This study was funded by the NHS National Institute for Health Research (NIHR) Programme Grants for Applied Research (PGfAR) scheme.

The trial is registered with the ISRCTN registry. Its unique number is 74121020.

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What were the aims of the ASCEND study?

In the UK, over 40,000 people receive a diagnosis of bowel cancer every year, and over 16,000 die from the disease. Studies suggest that screening the general population can help identify cancer at an earlier stage, when treatment is much more likely to be successful.

The English NHS Bowel Cancer Screening Programme was started in 2006 and aims to reduce the number of people dying from bowel cancer. Every two years, people aged between 60–74 years old are sent a test to look for hidden blood in the stool, which can sometimes be a sign of bowel cancer. This test is called a faecal occult blood test or FOBt. The test is completed at home and then returned in a prepaid envelope to a screening centre for analysis. It has been estimated that the risk of dying from bowel cancer is reduced, by about 25%, in those who regularly participate in FOBt screening, but not everyone takes part in screening when invited.

Findings from the NHS Bowel Cancer Screening Programme suggest that people living in more deprived areas are less likely to participate in the screening programme. This is concerning because these people are also more likely to die from bowel cancer. The decisions people make when it comes to screening participation are likely to be influenced by the way in which they are invited, and the information they receive with their invitation. The ASCEND study tested four different invitation/information strategies in the NHS Bowel Cancer Screening Programme to see if any could increase the numbers of people in more deprived areas participating in screening, without compromising already much higher participation in other areas.

What type of study was ASCEND?

Four different invitation/information strategies were tested as part of the ASCEND study and compared with the standard bowel cancer screening invitation letter to see if screening participation could be improved. During the study period, people invited for screening might have received, at random, one or a combination of the following as part of the ASCEND study:

  • The standard bowel cancer screening invitation letter;
  • A simplified summary leaflet;
  • A narrative leaflet which described individuals’ experiences of screening;
  • A statement of endorsement of the screening programme from the patient’s GP practice;
  • An enhanced reminder letter targeted specifically at those who had not responded.

No other aspects of the NHS Bowel Cancer Screening Programme were changed during the study. People received the same care as part of the screening programme regardless of whether they received an alternative invitation, or had their information used as part of the study.

When and where did this study take place?

The ASCEND study took place across England between November 2012 and August 2013.

What type of information does the CSPRG hold for the purposes of the ASCEND study?

The CSPRG does not hold personal data for purposes of the ASCEND study

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

Findings from the ASCEND study have been published in several journals including The Lancet. You can also access more information about this study and its findings on the UCL website.

Only one of the strategies tested, the enhanced reminder, increased the likelihood of people in the most deprived areas participating in screening. In addition, although it did not appear to particularly target more deprived areas, the GP practice endorsement modestly increased the likelihood that people in all areas would participate in screening, so this was also a positive finding.

It is hoped that these new invitation strategies will be implemented in the NHS Bowel Cancer Screening Programme as routine, to help reduce the risk of inequalities associated with screening and to improve overall participation.


Raine R, Atkin W, von Wagner C, et al. Testing innovative strategies to reduce the social gradient in the uptake of bowel cancer screening: a programme of four qualitatively enhanced randomised controlled trials. Southampton (UK): NIHR Journals Library; 2017 Mar

Raine R, Moss SM, von Wagner C, Atkin W, et al.  A national cluster-randomised controlled trial to examine the effect of enhanced reminders on the socioeconomic gradient in uptake in bowel cancer screening. Br J Cancer. 2016 Dec 6;115(12):1479-1486.

McGregor LM, von Wagner C, Atkin W, et al. Reducing the Social Gradient in Uptake of the NHS Colorectal Cancer Screening Programme Using a Narrative-Based Information Leaflet: A Cluster-Randomised Trial. Gastroenterol Res Pract. Vol 2016, Article ID 3670150

Raine R, Duffy SW, Wardle J, et al. Impact of general practice endorsement on the social gradient in uptake in bowel cancer screening. Br J Cancer. 2016 Feb 2;114(3):321-6.

Wardle J, von Wagner C, Kralj-Hans I, et al. Effects of evidence-based strategies to reduce the socioeconomic gradient of uptake in the English NHS Bowel Cancer Screening Programme (ASCEND): four cluster-randomised controlled trials. Lancet. 2016 Feb 20;387(10020):751-9