CT Colonography in the detection of Colorectal Cancer in Ireland; Economic considerations & the potential for centralisation of service provision.

W Torregianni, J Power, J Feeney.

Department of Radiology, Tallaght Hospital, Dublin

Colorectal cancer (CRC) is the second most common cancer in Ireland (excluding non melanomatous skin cancer)1. There were roughly 950 women and 1,330 men diagnosed with colorectal cancer annually in Ireland during 2007-2009.1 By 2020, with our aging population it is estimated that there will be an increase in colorectal cancer of 79 per cent in men and 56 per cent in women1.

Colorectal cancer screening by faecal occult blood testing has been shown to reduce CRC mortality. In Europe, colonoscopy is mainly used to investigate faecal occult blood test positive or symptomatic patients, or as a preventive strategy in those with increased CRC risk 2.

However there are many cases where colonoscopy is not feasible or contraindicated. In these situations, CT Colonography can be used as an alternative screening method.   It is a minimally invasive radiologic technique for imaging the colon which was first described in 19943  . Since its introduction it has been established as the optimal imaging test for assessing for colorectal cancer, replacing the barium enema4 ,5, 3. It is now included as a recommended completion test in certain situations for bowel screening as part of the national bowel screening programme.

CT Colongraphy has evolved in recent years and its role in colorectal cancer screening has become more defined with some of the emerging guidelines available including the guidelines for Use of CT Colonography as part of the National Colorectal Screening Programme in Ireland. Other guidelines include those provided by the British society for gastrointestinal and abdominal radiology and the royal college of radiologists London as well as several European guidelines.

The availability CT Colonography as an alternative to colonoscopy (for the correct indications) appears to be growing in Ireland, with thirty centres around Ireland providing CT Colonography and over 51 consultants reading CT Colonography6.  However, it is unlikely to take the place of colonoscopy in bowel screening. Referral rates for CT colonography are recommended to be less than 10 per cent of all those referred for colonoscopy following a positive fecal occult blood test7.

In the context of the bowel screening programme in Ireland, CT colonography is recommended as the completion test of screening in certain clinical scenarios. These include; if there is a failed colonoscopy or incomplete study; in those where a repeat colonoscopy is unlikely to be successful as the completion test; for those who are medically unfit for colonoscopy. It is common place with our aging population to be caring for patients with multiple co-morbidities. It is a useful alternative in for example a frail elderly patient with severe chronic obstructive airways disease, chronic renal disease or patients on certain anticoagulants.  In addition some elderly patients are too frail to undergo the laxative preparation for conventional colonoscopy3.

There are limitations to its screening potential however. CT colonoscopy is not suitable as a first line investigation for screening those with an increased risk of colorectal cancer such as those with a positive first-degree family history of colorectal cancer3.

CT Colonography is a relatively new technique and there is varying local practice with regard to study technique and interpretation. The accuracy of CT colonography appears to be quite dependent on good technique and reader training and expertise7. The development of regional chosen centres for the provision of CT Colonography as part of the National Bowel screening programme in Ireland may be a way to ensure consistency of the procedure and prevent varying local practices, similar to how there are 15 chosen Colonoscopy centres as part of the same programme. As with other national screening programmes which have been somewhat centralised, such as the diabetic retinal screening programme. Designated centres could ensure adequate planning, staffing levels, and uniformity of training of radiologists with regard to reporting of the examination. The Guidelines for the use of CT Colongraphy as part of the national cancer screening programme does set down recommendations for minimum acceptable training which Radiologists must undergo before they can safely report CT Colongraphy. However, it may be easier to monitor and audit this with the designation of chosen centres for provision of the service.

Furthermore, an important factor in the provision of a service is the cost effectiveness of that service. This was not discussed in the available Irish Guidelines with regard to cost effectiveness of CT Colonography. The resources recommended with regards to staffing and training is discussed in the Irish Guidelines8.  Economic considerations were briefly mentioned in the European (ESGAR)3, and perhaps discussed in more detail in the British guidelines9. There is a suggestion in the British guidelines that CT Colonography may be cost effective, as there is some evidence from the SIGGAR trials that most patients who have an abnormal colonoscopy result may eventually require CT imaging of the abdomen9,10.    Perhaps a more detailed review of the cost effectiveness of providing the service may be useful.

CT Colonography as part of the National Bowel screening programme will hopefully become more formalised as its role evolves. Further studies similar to the National Survey on CT Colongraphy6, are helpful in illiciting patterns of use, and provision of CT Colongraphy around Ireland. This kind of analysis will allow for greater planning for a better structure in the provision of the service as part of the screening programme for colorectal cancer in Ireland.


Dr William Torregianni, Adelaide and Meath National Children’s Hospital, Tallaght, Dublin 24, Dublin

Email: William.Torreggiani@amnch.ie


  1. National Cancer Registry Ireland http://www.ncri.ie/sites/ncri/files/pubs/ColorectalCancerIncidenceMortalityTreatmentandSurvivalinIreland1994-2010.pdf
  1. Rembacken B, Hassan C, Riemann JF et al (2012) Quality in screening colonoscopy: position statement of the European Society of Gastrointestinal Endoscopy (ESGE). Endoscopy 44:957–968
  1. ESGAR Guidelines http://link.springer.com/article/10.1007/s00330-014-3435-z
  1. European Commission (2010) European guidelines for quality assurance in colorectal cancer screening and diagnosis. http://www.uegf.org/eu_affairs/eu_news/CRC_guidelines_publication%20EU_2011.pdf
  1. Association of Coloproctology of Great Britain and Ireland (ACPGBI). Guidelines for the Management of Colorectal Cancer (3rd edition) 2007.
  1. E. Smyth, C.F. Healy, E.A. Aherne, P. MacMathuna, M.M. Morrin, H.M. Fenlon, Irish Medical Journal National survey on CT Colonography practice in Ireland http://imj.ie/national-survey-of-ct-colonography-practice-in-irelan/
  1. ie http://www.cancerscreening.ie/publications/Guidelines-for-Quality-Assurance-in-Colorectal-Screening.pdf
  1. Guidelines for the use of CT Colongraphy as part of the National Colorectal screening programme, Ireland. http://www.radiology.ie/wp-content/uploads/2012/01/Guidelines-for-Use-of-CT-Colonography-CTC-as-Part-of-the-National-Colorectal-Screening-Programme-in-Ireland1.pdf
  1. The Royal College of Radiologists London https://www.rcr.ac.uk/sites/default/files/publication/BFCR(14)9_COLON.pdf
  1. Halligan S, Wooldrage K, Dadswell E, et al: Computed tomographic colonography versus barium enema for diagnosis of colorectal cancer or large polyps in symptomatic patients (SIGGAR): A multicentre randomized trial. Lancet February 13, 2013