CT colonography raises screening rates, but colonoscopy finds more advanced neoplasia
Offering computed tomography (CT) colonography improved participation in colorectal cancer screening by more than 50% compared with conventional colonoscopy in a study conducted in the Netherlands. However, colonoscopy identified significantly more advanced neoplasia per 100 participants than did CT colonography.
Noting that screening for colorectal cancer is widely recommended but the preferred strategy remains unidentified, Evelien Dekker, MD, of the Academic Medical Centre in Amsterdam, the Netherlands, and colleagues sought to compare participation and diagnostic yield between screening with colonoscopy and with the less invasive CT colonography, a procedure that, unlike colonoscopy, does not require sedation. Members of the general Dutch population, aged 50 to 75 years, were invited for primary screening for colorectal cancer accomplished by one of the two methods.
A total of 1,276 (22%) of 5,924 colonoscopy invitees participated, compared with 982 (34%) of 2,920 CT colonography invitees. The investigators wrote in The Lancet Oncology that the most likely reason for the significant difference in participation rate is a difference in the expected burden or procedure-related complications. Regarding the latter, three people in the CT colonography group suffered the serious screening-related adverse event of postpolypectomy bleeding, compared with two people in the colonoscopy group.
The diagnostic yield (the likelihood that a procedure will provide the necessary information to establish a diagnosis, calculated as the number of participants with advanced neoplasia relative to the total number of invitees) for all advanced neoplasia was 8.7 per 100 colonoscopy participants vs 6.1 per 100 CT colonography participants, and 1.9 per 100 invitees for colonoscopy vs 2.1 per 100 invitees for CT colonography. The diagnostic yield for advanced neoplasia of 10 mm or more was 1.5 per 100 invitees for colonoscopy and 2.0 per 100 invitees for CT colonography.
The findings indicate either colonoscopy or CT colonography can be used for population-based screening for colorectal cancer, and factors such as cost-effectiveness and perceived burden should be taken into account when deciding which technique is preferable.