The adenoma detection rate in screening colonoscopy is higher than original cost-effectiveness models estimated.
Future colorectal cancer risk is decreased once the adenoma detection rates is 20%, but it is unclear how much additional protection is provided with higher adenoma detection rates.
Dr Gregory Austin and colleagues from Colorado, USA modeled the impact of a high adenoma detection rates on future colorectal cancer risk and surveillance colonoscopy burden.
created 3 hypothetical scenarios for 100,000 average-risk individuals undergoing screening colonoscopy at age 50.
The team investigated 20% adenoma detection rates with 30% future colorectal cancer risk reduction in Group 1.
|Future risk is reduced if a 50% adenoma detection rate leads to greater protection from colorectal cancer|
|American Journal of Gastroenterology|
Group 2 included 50% adenoma detection rate with 30% future colorectal cancer risk reduction.
Group 3 included 50% adenoma detection rates with 50% future colorectal cancer risk reduction.
After colonoscopy, the team noted that patients could have high-risk or low-risk adenomas, or no adenomas.
When the adenoma detection risk increases from 20% to 50% but no additional colorectal cancer cases are prevented, future colorectal cancer risk for each group is still reduced, because lower-risk patients migrate into apparently higher-risk groups (the Will Rogers phenomenon).
The research team found that future risk is further reduced if a 50% adenoma detection rate leads to greater protection from colorectal cancer.
However, despite the reductions in group-specific and overall future colorectal cancer risk, 34,635 additional surveillance colonoscopies are performed before the cohort is 60 years old when the adenoma detection rate is 50% compared with 20%.
Dr Austin's team concludes, "If current surveillance practices continue along with high adenoma detection rates, screening colonoscopy may not remain cost-effective."