POST-COLONOSCOPY COLORECTAL CANCERS - SHOULD WE BE ASPIRING TO BETTER TARGETS?

Aims The British Society of Gastroenterology (BSG) have developed quality assurance measures for the delivery of colonoscopy within the UK. One of these includes aspiring to a target of < 5% post-colonoscopy colorectal cancers (PCCRC) at 3 years. We aimed to describe risk factors for missed colorectal cancers.

Methods Retrospective study across two sites at a tertiary London-based hospital Trust. Endoscopy software was used to identify all new colorectal cancers diagnosed during colonoscopy (May 2017 to September 2018). PCCRC rate was defined as the proportion of PCCRC diagnoses amongst all CRC cases within a 3 year period.

Results 282 cases of colorectal cancer diagnosed during colonoscopy. There were a total of 8 cases of PCCRC within 3 years giving our Trust a PCCRC rate of 2.8%. Mean age of patients with a PCCRC diagnosis was 75.8 (64 - 88). Mean interval from initial to diagnostic colonoscopy in PCCRC cases was 2.08 years (0.92 - 3). 7 of the 8 cases (87.5%) were colonoscopies performed by surgeons or external agency endoscopists. 4 of the 8 cases (50%) had less than good bowel preparation. Retroflexion in the rectum was not performed in 6 of the 8 cases (75%). When PCCRC diagnoses were extended to within 5 years the rate was 4.3%.

Conclusions Our Trust is within the quality standards set by the relevant governing bodies. Root cause analyses identified caecal, sigmoid and anastomotic lesions as high risk sites for missed cancers as well as omission of retroflexion in the rectum. Accepting less than good bowel preparation is also a factor in half of PCCRC cases. In view of the advances made in the quality of colonoscopy training and enhanced endoscopic technology, we suggest raising the bar with regards to acceptable PCCRC by either lowering the target or increasing the time frame to 5 years.