Abstract
Background Colorectal cancer (CRC) diagnosed following a cancer-negative colonoscopy is termed
post-colonoscopy CRC (PCCRC). In addition to calculating PCCRC rates, the World Endoscopy
Organization (WEO) recommends review of individual PCCRC cases, including categorization
into interval/non-interval PCCRCs, and root cause analysis to determine the most plausible
explanation. We aimed to test the usability, reproducibility, and outcomes of the
WEO algorithms.
Methods All CRC cases diagnosed from January 2015 to December 2016 in a single organization
were cross referenced with local endoscopy and pathology databases to identify cases
of PCCRC. We assessed: 1) WEO most plausible explanation for PCCRC; and 2) WEO PCCRC
interval/non-interval subtype categorization. Interobserver agreement was measured
using Cohen’s kappa (κ). Cases with interobserver variation underwent panel discussion
to reach consensus.
Results Among 527 patients with CRC, 48 PCCRCs were identified. A consistent most plausible
explanation was found in 97 % of cases, showing almost perfect agreement (κ = 0.94).
Most PCCRCs (66 %) were attributed to “possible missed lesion, prior examination adequate.”
Interval/non-interval categorization was consistent in 77 %, showing substantial agreement
(κ = 0.67). Following panel discussion, consensus was reached in all cases. Overall,
15 % were categorized as interval and 85 % as non-interval PCCRCs (12 % type A, 31 %
type B, and 42 % type C).
Conclusions Review of PCCRC cases using WEO recommendations was performed accurately at a local
level using readily available clinical information. The high number of non-interval
type B PCCRCs suggests a significant proportion of PCCRCs could be avoided by better
adherence to recommended surveillance intervals.
