CT Colonoscopy Source: TeraRecon

Participation in colorectal cancer screening was significantly better using CT colonography compared with conventional colonoscopy, suggesting that CT colonography could be useful as an additional primary screening test, according to research published online Nov. 15 in The Lancet Oncology.

Despite the fact that most colorectal cancers are preventable and treatable, nearly 50,000 people will die from the disease this year in the U.S., according to the National Cancer Institute. Colonoscopy screening can identify and lead to the removal of polyps before they become cancerous, but participation is generally low.

“The bottom line is quite simple—too many people are dying of a readily preventable disease,” Perry Pickhardt, MD, of the School of Medicine and Public Health, University of Wisconsin in Madison, wrote in an accompanying comment. “The issue with screening for colorectal cancer is not related to test efficacy per se, but rather to the willingness of patient participation (and study availability). By offering the additional option of CT colonography for screening, overall patient outcomes will be positively affected by the equivalent (or greater) yield for advanced neoplasia coupled with a decrease in complications and costs.”

Evelien Dekker, MD, of the department of gastroenterology and hepatology at Academic Medical Centre in Amsterdam, and colleagues sought to compare participation and diagnostic yield between screening with conventional colonoscopy and CT colonography. The study included average-risk individuals, aged 50 to 75 years, from the general Dutch population in Amsterdam and Rotterdam who were randomly allocated to be invited for colorectal cancer screening by colonoscopy or by CT colonography.

Nearly 9,000 total invitations were sent out, 5,924 for colonoscopy and 2,920 for CT colonography. Results showed that 22 percent of colonoscopy invitees participated, compared with 34 percent of the CT colonography invitees.

“Since the invitational processes for colonoscopy and CT colonography in our study were identical, the most probable reason for the significant difference in participation rate is a difference in the expected burden or procedure-related complications,” wrote the authors.

Colonoscopy identified significantly more advanced neoplasia per 100 participants than CT colonography (8.7 versus 6.1). Despite the relative effectiveness of colonoscopy among participants, because of the higher participation rates among CT colonography invitees, the total diagnostic yield of identified advanced neoplasia was 1.9 per 100 invitees for colonoscopy and 2.1 per 100 invitees for CT colonography.

“The diagnostic yield for advanced neoplasia per 100 invitees was similar for both strategies, indicating that both techniques can be used for population-based screening for colorectal cancer,” wrote Dekker and colleagues. “Other factors such as cost-effectiveness and perceived burden should be taken into account when deciding which technique is preferable.”

There was little difference between the two procedures in the number of serious adverse events related to the screening.

"The additive yields of having both colonoscopy and CT colonography available as primary screening options could have a profound effect on the incidence and mortality of colorectal cancer in the future," wrote Pickhardt.