Adenoma detection rate is inversely associated with post-colonoscopy colorectal cancer risk

1. In this prospective cohort study, the adenoma detection rate (ADR) was inversely associated with colorectal cancer (CRC) risk in fecal immunochemical testing (FIT)-based screening programs.

2. The most common location for post-colonoscopy colorectal cancer diagnosis was the proximal colon, followed by the distal colon and rectum.

Evidence Rating Level: 2 (Good)

Study Rundown: FIT is an essential preventive intervention for colorectal screening. Although, colonoscopy is more accurate than FIT testing in detected CRC. There also continues to be high variability in ADR between endoscopists. In the present study, a total of 113 endoscopists’ colonoscopy outcomes were examined, where the ADR ranged from 23.0% to 70.0%. Endoscopists were stratified based on ADR. The incidence of unadjusted CRC increased from the first to the fifth ADR group. The difference in incidence rates persisted across groups throughout follow-up. An inverse association between post-colonoscopy colorectal cancer (PCCRC) incidence risk was seen across ADR groups. The risk was two-fold higher for PCCRC in patients who received endoscopies from those in the lowest ADR group compared to the highest ADR group. A similar trend was seen for unadjusted incidence rates for PCCRC across advanced adenoma detection rates (AADR). Individuals who received colonoscopies from the lowest AADR group compared to the highest AADR had a 1.7 times higher risk for PCCRC. This study suggests that an increase in ADR would lead to a significant PCCRC incidence risk reduction in FIT-based screening programs. This study may be subject to a bias in which endoscopists with higher ADR recommend more frequent testing.

Click to read the study in AIM

Relevant Reading: Long-term colorectal cancer incidence and mortality after a single negative screening colonoscopy

In-Depth [prospective cohort study]: In this observational cohort study, the relationship between individual endoscopist ADR and AADR and subsequent risk for PCCRC was examined. A population-based CRC screening program in northeastern Italy was examined, where residents aged 50 to 69 years are invited every two years to do a single FIT. Persons with a positive FIT were then invited for colonoscopy. Those with advanced adenoma were sent to one or three-year surveillance colonoscopy, and those with nonadvanced adenoma or negative colonoscopy were sent to a new FIT round in the second or fifth year. A total of 49,626 colonoscopies and 113 endoscopists were included in the final analyses. The ADR ranged from 23.0% to 70.0% (median 48.0%), whereas the AADR ranged from 11.9% to 46.0% (median 27.4%). Further, 277 cases of PCCRC were diagnosed, 1.8% between 6 and 11 months after index colonoscopy, 24.2% between 12 and 35 months, 30.3% between 36 and 59 months, and 43.7% were 60 months or greater. The anatomical locations for PCCRC were the proximal colon (43.0%), distal colon (20.9%), and rectum (21.3%). The unadjusted CRC incidence rates across ADR groups (from first to fifth) were 13.13, 10.61, 7.60, 6.01, and 5.78 per 10,000 person-years follow-up. Colonoscopies completed by those in the first ADR group compared to the fifth ADR group had a two-fold higher risk for PCCRC (95% Confidence Interval, 1.63 to 3.38). The unadjusted incidence rates for PCCRC across AADR groups were 10.54, 9.95, 7.82, 7.45, and 6.34. Colonoscopies completed by those in the first AADR group compared to fifth AADR group had a 1.7-fold higher risk for PCCRC (95% CI, 1.21 to 2.58). In summary, the present study demonstrates that an increase in ADR may result in PCCRC incidence risk reduction in FIT-based screening programs.

Image: PD

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