Prevalence and characteristics of post-colonoscopy colorectal cancers in a New Zealand regional centre: a 10-year analysis

Protocol for a national, multicentre study of post-endoscopy colorectal and upper gastrointestinal cancers: The POET study

AIM

The primary aim of the study is to define the post-colonoscopy colorectal cancer (PCCRC) three-year rate and the post-endoscopy upper gastrointestinal cancer (PEUGIC) three-year rate across public hospitals in Aotearoa New Zealand.

METHOD

This retrospective cohort study will be conducted via the trainee-led STRATA Collaborative network. All public hospitals in Aotearoa New Zealand will be eligible to participate. Data will be collected on all adult patients who are diagnosed with colorectal adenocarcinoma within 6 to 48 months of a colonoscopy and all adult patients diagnosed with gastroesophageal cancer within 6 to 48 months of an upper gastrointestinal endoscopy. The study period will be from 2010 to 2022. The primary outcome is the PCCRC 3-year rate and the PEUGIC 3-year rate. Secondary aims are to define and characterize survival after PCCRC or PEUGIC, the cause of PCCRC as based on the World Endoscopy Organization System of Analysis definitions, trends over time, and centre level variation.

CONCLUSION

This protocol describes the methodology for a nationwide retrospective cohort study on PCCRC and PEUGIC in Aotearoa New Zealand. These data will lay the foundation for future studies and quality improvement initiatives.

Risk of a post-colonoscopy colorectal cancer in patients with diverticular disease: a population-based cohort study

BACKGROUND

Post-colonoscopy colorectal cancers (PCCRCs) may account for up to 30% of all colorectal cancers (CRCs) diagnosed in patients with diverticular disease; however, absolute and relative risks of PCCRC among these patients undergoing colonoscopy remain unknown.

METHODS

We performed a cohort study (1995-2015) including patients with and without diverticular disease who underwent colonoscopy. We calculated 7-36-month cumulative incidence proportions (CIPs) of PCCRC. We used Cox proportional hazards regression models to compute hazard ratios (HRs) of PCCRC, comparing patients with and without diverticular disease, as a measure of relative risk. We calculated 3-year PCCRC rates, as per World Endoscopy Organization recommendations, to estimate the proportion of CRC patients with and without diverticular disease who were considered to have PCCRC. We stratified all analyses by PCCRC location.

RESULTS

We observed 373 PCCRCs among 56 642 patients with diverticular disease and 1536 PCCRCs among 306 800 patients without diverticular disease. The PCCRC CIP after first-time colonoscopy was 0.45% (95%CI 0.40%-0.51%) for patients with and 0.36% (95%CI 0.34%-0.38%) for patients without diverticular disease. Comparing patients with and without diverticular disease undergoing first-time colonoscopy, the adjusted HR was 0.84 (95%CI 0.73-0.97) for PCCRC and 1.23 (95%CI 1.01-1.50) for proximal PCCRCs. The 3-year PCCRC rate was 19.0% (22.3% for proximal PCCRCs) for patients with and 6.5% for patients without diverticular disease.

CONCLUSIONS

Although the absolute risk was low, the relative risk of proximal PCCRCs may be elevated in patients with diverticular disease undergoing colonoscopy compared with patients without the disease.

Analysis of Post-Colonoscopy Colorectal Cancer and Its Subtypes in a Screening Programme

Using the algorithm of the World Endoscopy Organisation (WEO), we have studied retrospectively all colorectal cancers, both detected and non-detected by the Basque Country screening programme from 2009 to 2017. In the screening programme 61,335 colonoscopies were performed following a positive Faecal Immunochemical test (FIT) (≥20 µg Hb/g faeces) and the 128 cases of post-colonoscopy colorectal cancer (PCCRC) detected were analysed. Among them, 50 interval type PCCRCs were diagnosed (before the recommended surveillance), 0.8 cases per 1000 colonoscopies performed, and 78 non-interval type PCCRCs (in the surveillance carried out at the recommended time or delayed), 1.3 per 1000 colonoscopies. Among the non-interval type PCCRCs, 61 cases were detected in the surveillance carried out at the recommended time (type A) and 17 when the surveillance was delayed (type B), 1 case per 1000 colonoscopies performed and 0.28 cases per 1000 colonoscopies performed, respectively. Interval type PCCRC is less frequent than non-interval type PCCRC. In interval type PCCRCs, CRCs detected in advanced stages (stages III-IV) were significantly more frequent than those detected in early stages, compared to those of non-interval type PCCRCs (OR = 3.057; 95% CI, 1.410-6.625; p < 0.005). Non-interval type B PCCRCs are less frequent than non-interval type A PCCRCs, but the frequency of advanced stages is higher in interval type B PCCRCs.

A single-centre analysis of post-colonoscopy colorectal cancer

PATIENTS AND METHODS

A prospective registration of patients with colorectal cancer and a colonoscopy within the last 10 years. We tried to classify these post-colonoscopy colorectal cancers (PCCRCs) by most reasonable explanation and into subcategories suggested by the World Endoscopy Organization (WEO) and calculated the unadjusted PCCRC rate.

RESULTS

47 PCCRCs were identified. The average age at diagnosis of PCCRC was 73 years. PCCRCs were more located in the right colon with a higher percentage of MSI-positive and B-RAF mutated tumours. The average period between index colonoscopy and diagnosis of PCCRC was 4.2 years. Sixty-eight % of all PCCRCs could be explained by procedural factors. The mean PCCRC-3y of our department was 2.46%.

CONCLUSIONS

The data of our centre are in line with the data of the literature from which can be concluded that most postcolonoscopy colorectal cancers are preventable. The PCCRC-3y is an important quality measure for screening colonoscopy. Ideally all centres involved in the population screening should measure the PCCRC-3 y annually, with cooperation of the cancer registry and reimbursement data provided by the Intermutualistic Agency (IMA).