Slightly more than 50% of people with an inherited risk for colorectal cancer (CRC) agree to undergo screening for this cancer, and most prefer colonoscopy to colon capsule endoscopy—even though these are equally effective screening tools—researchers report in the December issue of Clinical Gastroenterology and Hepatology. Colonoscopy should therefore remain the first-choice screening strategy for subjects with a familial risk of CRC, with colon capsule endoscopy as an acceptable alternative.
Risk of CRC increases 2-fold to 5-fold in first-degree relatives of individuals who were younger than 60 years when they developed the cancer, or in persons with 2 or more first-degree relatives with CRC. Clinical practice guidelines therefore recommend colonoscopy every 5 years, starting at the age of 40 or 10 years less than the index case at first diagnosis.
Colonoscopy is standard procedure for detecting CRC and advanced adenomas. One advantage of colonoscopy over other screening tests is that polypectomy can be performed during the examination. However, colonoscopy is an invasive procedure that can produce complications. Fewer than 40% of people with a familial risk of CRC therefore undergo their recommended colonoscopies.
Colon capsule endoscopy is a minimally invasive procedure that detects advanced neoplasia with a similar level of accuracy to colonoscopy. It has therefore been proposed as a cost-effective alternative to colonoscopy that might increase screening uptake.
Zaida Adrián-de-Ganzo performed a prospective, randomized controlled study to compare uptake of CRC screening by colonoscopy vs colon capsule endoscopy in asymptomatic individuals in Spain who were at risk for CRC.
Subjects were randomly assigned to groups examined by colon capsule endoscopy (PillCam, second generation) or colonoscopy. They were allowed to crossover between groups if they did not wish to undergo the assigned procedure. Subjects assigned to colon capsule endoscopy who had a significant lesion (polyp ≥10 mm, >2 polyps of any size, or CRC) were invited to undergo colonoscopy to remove the lesion.
Among the 120 participants who were assigned to undergo colon capsule endoscopy, 52 declined to be screened (43.3%), and 68 agreed to participate (56.6%). Overall, 29 (24.2%) accepted the assigned strategy and 28 (23.3%) finally underwent colon capsule endoscopy, whereas 39 (32.5%) who declined CCE chose to undergo colonoscopy instead (see figure).
Among the 113 participants who were invited to undergo colonoscopy, 50 declined (44.2%) and 63 agreed to participate (55.8%). Of these, 44 accepted the assigned strategy (38.9%) and 42 (37.1%) finally underwent colonoscopy, whereas 17 (15%) who declined colonoscopy chose to undergo colon capsule endoscopy instead.
Consequently, the rate of crossover was significantly higher from the colon capsule endoscopy group (57.4%) than the colonoscopy group (30.2%).
Unwillingness to repeat bowel preparation in the case of a positive result was the main reason that subjects assigned to the colon capsule endoscopy group crossed over, whereas fear of colonoscopy was the reason that most patients reported switching from this group.
A significant lesion was detected in 14 subjects (11.7%) in the colon capsule endoscopy group and 13 subjects (11.5%) in the colonoscopy group.
The authors conclude that contrary to expectations, colon capsule endoscopy does not increase screening in subjects with a familial risk of CRC. Furthermore, the high rate of crossover from the colon capsule endoscopy group to the colonoscopy group indicates greater acceptance of colonoscopy as a cancer screening procedure.
However, Adrián-de-Ganzo et al explain that the main reason that many patients did not want to undergo colon capsule endoscopy in this study was probably because they knew they would have to undergo a second bowel preparation and a colonoscopy, on another day, in the event of a positive finding. In fact, “to avoid a second bowel preparation in the event of a positive result” was the most frequent answer (89%) given by individuals assigned to colon capsule endoscopy who decided to switch groups.
The authors say that use of intravenous sedation for colonoscopies, associated with a reported “good” experience by many patients, could be another reason for the preference.
Adrián-de-Ganzo et al mention that colon capsule endoscopy is about 2-fold more expensive than colonoscopy, so it is unlikely to be more cost effective than colonoscopy screening.
In an editorial in the same issue, Cristiano Spada et al explain that choice of diagnostic test does not have much effect on the decision to participate in screening. Barriers other than fear of colonoscopy prevent almost half of first-degree relatives of CRC patients to be screened. Adrián-de-Ganzo et al did not analyze the reasons for screening refusal, but it is likely that patient education will be required to increase screening uptake.
Spada et al added that among individuals who agree to undergo screening, awareness of the increased CRC risk seems to marginalize the fear of colonoscopy, so that the minimal invasiveness of CCE became irrelevant. However, Spada et al. point out that 15% of patients eligible for colonoscopy chose colon capsule endoscopy instead, indicating the importance of this procedure for a specific population of patients.