CT Colonography: Accuracy, Acceptance, and Safety
CT Colonography: Accuracy, Acceptance, and Safety
In a screening trial performed in the USA, approximately 8% of 3120 CTC screenees were referred for colonoscopy, leading to detection of advanced neoplasia in 3.2% of CTC screenees, compared with 3.4% of 3163 colonoscopy screenees (figures 1–3). The yield per 100 participants was higher within a randomised screening trial performed in the Netherlands where 2920 individuals were invited: 8.7 per 100 colonoscopy participants and 6.1 per 100 CTC participants. Here, only CTC participants with one or more lesions ≥10 mm were referred for colonoscopy, and those with 6–9 mm lesions were offered CTC surveillance. Of note, this trial reported a significantly higher participation rate for CTC than for colonoscopy: 34% and 22%, respectively (a 55% increase). Although the diagnostic yield per participant was higher in colonoscopy, the diagnostic yield for advanced neoplasia per invitee was similar due to the higher uptake in CTC screening: 1.9 per 100 colonoscopy invitees versus 2.1 per 100 CTC invitees. This illustrates the importance of considering the ultimate diagnostic yield per invitee between different screening techniques, rather than simply the differences in accuracy. First-round sigmoidoscopy screening resulted in a comparable yield (2.2 per 100 invitees), as well as first-round faecal immunochemical test (FIT) screening (2.0/100) when using a cut-off of 50 ngHb/mL.
In most countries, FIT screening is repeated at 2-year intervals, whereas colonoscopy and sigmoidoscopy screening are repeated every 5–10 years. For CTC, similar 5-year to10-year intervals might be used. At this point, the question remains whether the adherence to screening will be comparable in different rounds and whether cumulative yield of the different screening rounds will be approximately the same for each screening technique after a screening period for 10 or 20 years, for example. The adherence to a two-round FIT screening over 2 years was not significantly different between two screening rounds, the diagnostic yield of the second screening round was significantly lower compared with the first round. To our knowledge, no studies have been published on the adherence to, and the diagnostic yield of, CTC screening when applied every 5 or 10 years. Surveillance adherence data from the Dutch population-based CTC screening trial will probably be available soon. Data on the diagnostic yield from the second round of screening with CTC at 5–10 years is also expected within the next year or so from the University of Wisconsin CTC screening programme.
CTC Screening: Attendance, Diagnostic Yield and Adherence
In a screening trial performed in the USA, approximately 8% of 3120 CTC screenees were referred for colonoscopy, leading to detection of advanced neoplasia in 3.2% of CTC screenees, compared with 3.4% of 3163 colonoscopy screenees (figures 1–3). The yield per 100 participants was higher within a randomised screening trial performed in the Netherlands where 2920 individuals were invited: 8.7 per 100 colonoscopy participants and 6.1 per 100 CTC participants. Here, only CTC participants with one or more lesions ≥10 mm were referred for colonoscopy, and those with 6–9 mm lesions were offered CTC surveillance. Of note, this trial reported a significantly higher participation rate for CTC than for colonoscopy: 34% and 22%, respectively (a 55% increase). Although the diagnostic yield per participant was higher in colonoscopy, the diagnostic yield for advanced neoplasia per invitee was similar due to the higher uptake in CTC screening: 1.9 per 100 colonoscopy invitees versus 2.1 per 100 CTC invitees. This illustrates the importance of considering the ultimate diagnostic yield per invitee between different screening techniques, rather than simply the differences in accuracy. First-round sigmoidoscopy screening resulted in a comparable yield (2.2 per 100 invitees), as well as first-round faecal immunochemical test (FIT) screening (2.0/100) when using a cut-off of 50 ngHb/mL.
In most countries, FIT screening is repeated at 2-year intervals, whereas colonoscopy and sigmoidoscopy screening are repeated every 5–10 years. For CTC, similar 5-year to10-year intervals might be used. At this point, the question remains whether the adherence to screening will be comparable in different rounds and whether cumulative yield of the different screening rounds will be approximately the same for each screening technique after a screening period for 10 or 20 years, for example. The adherence to a two-round FIT screening over 2 years was not significantly different between two screening rounds, the diagnostic yield of the second screening round was significantly lower compared with the first round. To our knowledge, no studies have been published on the adherence to, and the diagnostic yield of, CTC screening when applied every 5 or 10 years. Surveillance adherence data from the Dutch population-based CTC screening trial will probably be available soon. Data on the diagnostic yield from the second round of screening with CTC at 5–10 years is also expected within the next year or so from the University of Wisconsin CTC screening programme.
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