Postcolonoscopy Colorectal Cancer in Fecal Immunochemical Test-Positive Individuals: Prevalence, Predictors, and Root Cause Analysis in a Nationwide Cohort.

INTRODUCTION

Postcolonoscopy colorectal cancer (PCCRC) represents an important real-world colonoscopy quality indicator. Using a national database, we evaluated predictors of PCCRC in fecal immunochemical test (FIT)-positive individuals, determined the PCCRC 3-year (PCCRC-3y) rate, and performed a root cause analysis (RCA).

METHODS

This retrospective cohort study evaluated FIT-positive patients who underwent colonoscopy from January 2015 to July 2022. Data were collected from the Veterans Affairs national database. PCCRC was defined as CRC detected ≥6 months after colonoscopy. CRC was identified using Systematized Nomenclature of Medicine codes and the Veterans Affairs Cancer Registry. The World Endoscopy Organization methodology was used to perform the RCA and calculate the PCCRC-3y rate.

RESULTS

We identified 132 PCCRCs among 52,167 FIT-positive individuals. The PCCRC-3y rate was 6.4% (95% confidence interval [CI] 5.0%-7.7%). PCCRC locations were proximal colon (43.2%), distal colon (34.8%), and rectum (22%). Root causes were likely new CRC (17.4%), missed lesions with adequate (31.2%) or inadequate (9.8%) examination, incomplete polyp resection (22%), and detected but unresected lesions (19.7%). 16.7% of patients with PCCRC had poor bowel preparation on index colonoscopy. The cecal intubation rate was 88.6%, and rectal retroflexion rate was 84.5%. In 14.4% of cases, recommended surveillance intervals did not adhere to established guidelines. Independent predictors of PCCRC were ages 70-79 years (hazard ratio [HR] 7.86; 95% CI 1.08-57.39), age ≥80 years (HR 10.18; 95% CI 1.06-97.98), tubulovillous adenoma (HR 3.98; 95% CI 2.52-6.29), and adenoma with high-grade dysplasia (HR 10.15; 95% CI 5.91-17.42).

DISCUSSION: Among FIT-positive individuals, the PCCRC-3y rate was 6.4%, with missed lesions and incomplete resection as key contributors. These findings provide useful information on quality metrics in FIT-based CRC-screening programs.