Abstract
Background Post-colonoscopy colorectal cancers (PCCRCs) decrease the effect of colorectal cancer
(CRC) screening programs. To enable PCCRC incidence reduction in the long-term, we
classified PCCRCs diagnosed after colonoscopies performed in a fecal immunochemical
test (FIT)-based screening program.
Methods PCCRCs diagnosed after colonoscopies performed between 2014–2016 for a positive FIT
in the Dutch CRC screening program were included. PCCRCs were categorized according
to the World Endoscopy Organization consensus statement into (a) interval PCCRC (diagnosed
before the recommended surveillance); (b) non-interval type A (diagnosed at the recommended
surveillance interval); (c) non-interval type B (diagnosed after the recommended surveillance
interval); or (d) non-interval type C (diagnosed after the intended recommended surveillance
interval, with surveillance not implemented owing to co-morbidity). The most probable
etiology was determined by root-cause analysis. Tumor stage distributions were compared
between categories.
Results 116362 colonoscopies were performed after a positive FIT with 9978 screen-detected
CRCs. During follow-up, 432 PCCRCs were diagnosed. The 3-year PCCRC rate was 2.7%.
PCCRCs were categorized as interval (53.5%), non-interval type A (14.6%), non-interval
type B (30.6%), and non-interval type C (1.4%). The most common etiology for interval
PCCRCs was possible missed lesion with adequate examination (73.6%); they were more
often diagnosed at an advanced stage (stage III/IV; 53.2%) compared with non-interval
type A (15.9%; P<0.001) and non-interval type B (40.9%; P=0.03) PCCRCs.
Conclusions The 3-year PCCRC rate was low in this FIT-based CRC screening program. Approximately
half of PCCRCs were interval PCCRCs. These were mostly caused by missed lesions and
were diagnosed at a more advanced stage. This emphasizes the importance of high quality
colonoscopy with optimal polyp detection.
