Clinical and endoscopist factors associated with post-colonoscopy colorectal cancer in a population-based sample

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.

Type 2 diabetes mellitus and post-colonoscopy colorectal cancer: clinical and molecular characteristics and survival

PURPOSE

Studies suggest that patients with type two diabetes mellitus (T2D) may be at increased risk of post-colonoscopy colorectal cancer (PCCRC). We investigated clinical and molecular characteristics and survival of T2D patients with PCCRC to elucidate how T2D-related PCCRC may arise.

METHODS

We identified T2D patients with colorectal cancer (CRC) from 1995 to 2015 and computed prevalence ratios (PRs) comparing clinical and molecular characteristics of CRC in T2D patients with PCCRC vs. in T2D patients with colonoscopy-detected CRC (dCRC). We also followed T2D patients from the diagnosis of PCCRC/dCRC until death, emigration, or study end and compared mortality using Cox-proportional hazards regression models adjusted for sex, age, year of CRC diagnosis, and CRC stage.

RESULTS

Compared with dCRC, PCCRC was associated with a higher prevalence of proximal CRCs (54% vs. 40%; PR: 1.43, 95% confidence interval [CI] 1.27-1.62) in T2D patients. We found no difference between PCCRC vs. dCRC for CRC stage, histology, and mismatch repair status. The proportion of CRCs that could be categorized as PCCRC decreased over time. Within one year after CRC, 63% of PCCRC vs. 78% of dCRC patients were alive (hazard ratio [HR] 1.85 [95% CI 1.47-2.31]). Within five years after CRC, 44% of PCCRC vs. 54% of dCRC patients were still alive (HR 1.44 [95% CI 1.11-1.87]).

CONCLUSION

The increased prevalence of proximally located PCCRCs and the poorer survival may suggest overlooked colorectal lesions as a predominant explanation for T2D-related PCCRC, although altered tumor progression cannot be ruled out.

Incidence, characteristics, and predictive factors of post-colonoscopy colorectal cancer

BACKGROUND

Post-colonoscopy colorectal cancer (PCCRC) is colorectal cancer (CRC) diagnosed after a colonoscopy in which no cancer is found.

OBJECTIVE

As PCCRC has become an important quality indicator, we determined its rates, characteristics, and index colonoscopy-related predictive factors.

METHODS

We carried out a multicenter, observational, retrospective study between 2015 and 2018. Rates were calculated for PCCRC developing up to 10 years after colonoscopy. PCCRC was categorized according to the most plausible explanation using World Endoscopy Organization methodology. Our PCCRC population was compared to a control cohort without CRC matched 1:4 by sex, age, index colonoscopy date, indication, endoscopist, and hospital.

RESULTS

One hundred seven PCCRC and 2508 detected CRC were diagnosed among 101,524 colonoscopy (0.1%), leading to rates of 0.4%, 2.2%, 3.1%, and 4.1% at 1, 3, 5, and 10 years, respectively. PCCRC was in right (42.4%), left (41.4%), and transverse (16.4%) colon with 31.5% at stage I, 24.7% stage II, 32.6% stage III, and 11.2% stage IV. Twenty point three percent were classified as incomplete resection, 5.4% as unresected lesions, 48.6% as missed lesions with adequate colonoscopy, and 25.7% as missed lesions with inadequate colonoscopy. The median time from colonoscopy to PCCRC was 42 months. Previous inadequate preparation (OR 3.05, 95%CI 1.73-5.36) and piecemeal polypectomy (OR 19.89, 95%CI 8.67-45.61) were independently associated with PCCRC.

CONCLUSIONS

In our population, 4.1% of CRC cases were PCCRC. Most of these lesions were in right colon and attributable to lesions not visualized despite adequate bowel cleansing. Previous inadequate cleansing and piecemeal polypectomy were associated with PCCRC.

Clinical and Genomic Characterization of Interval Colorectal Cancer in 3 Prospective Cohorts

BACKGROUND & AIMS

Interval colorectal cancers (CRCs), cancers diagnosed after a screening/surveillance examination in which no cancer is detected, and before the date of next recommended examination, reflect an unprecedented challenge in CRC detection and prevention. To better understand this poorly characterized CRC variant, we examined the clinical and mutational characteristics of interval CRCs in comparison with screen detected CRCs.

METHODS

We included 1175 CRCs documented in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial and 3661 CRCs in the Nurses' Health Study (NHS) and Health Professionals Follow-up Study (HPFS). Multivariable Cox models were performed to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of death risk. Whole exome sequencing was conducted in 147 PLCO cases and 796 NHS/HPFS cases.

RESULTS

A total of 619 deaths (312 CRC-specific) and 2404 deaths (1904 CRC-specific) were confirmed during follow-up of PLCO and NHS/HPFS, respectively. Compared with screen detected CRCs, interval CRCs had a multivariate-adjusted HR (95% CI) of 1.47 (1.21-1.78) for CRC-specific mortality and 1.27 (1.09-1.47) for overall mortality (meta-analysis combining all 3 cohorts). However, we did not observe significant differences in mutational features between interval and screen detected CRCs (false discovery rate adjusted P > .05).

CONCLUSION

Interval CRCs had a significantly increased risk of death compared with screen detected CRCs that were not explained by established clinical prognostic factors, including stage at diagnosis. The survival disadvantage of interval CRCs did not appear to be explained by differences in the genomic landscape of tumors characterized by whole exome sequencing.

Characteristics and Survival of Patients With Inflammatory Bowel Disease and Postcolonoscopy Colorectal Cancers

BACKGROUND & AIMS

Postcolonoscopy colorectal cancers (PCCRCs) account for up to 50% of colorectal cancers (CRCs) in patients with inflammatory bowel disease (IBD). We investigated characteristics of IBD patients with PCCRC and their survival.

METHODS

We identified IBD patients (ulcerative colitis [UC] and Crohn's disease) diagnosed with CRC from 1995 to 2015. We defined PCCRC as diagnosed between 6 and 36 months, and detected CRC (dCRC) as diagnosed within 6 months after colonoscopy. We computed prevalence ratios comparing PCCRC vs dCRC and followed up patients from the diagnosis of PCCRC/dCRC until death, emigration, or study end. Mortality was compared using Cox proportional hazards regression models adjusted for sex, age, year of CRC diagnosis, and stage. The main analyses focused on patients with UC.

RESULTS

Among 23,738 UC patients undergoing colonoscopy, we identified 352 patients with CRC, of whom 103 (29%) had PCCRC. Compared with dCRC, PCCRC was associated with a higher prevalence of metastatic cancer (33% vs 20%; prevalence ratio, 1.64; 95% CI, 1.13-2.38), cancers showing mismatch repair deficiency (79% vs 56%; prevalence ratio, 1.40; 95% CI, 1.13-1.72), and proximally located cancers (54% vs 40%; prevalence ratio, 1.34; 95% CI, 1.06-1.69). The 1- and 5-year adjusted hazard ratios of death for PCCRC vs dCRC among UC patients were 1.29 (95% CI, 0.77-2.18) and 1.24 (95% CI, 0.86-1.79), respectively.

CONCLUSIONS

The characteristics of UC-related PCCRC suggest tumor biology as an important factor in the progression to cancer. However, the prognosis of PCCRC appears similar to that of dCRC.

Systematic review with meta-analysis: the prevalence of post-colonoscopy colorectal cancers using the World Endoscopy Organization nomenclature

INTRODUCTION

Post-colonoscopy colorectal cancers (PCCRCs) have been proposed as a performance metric for colonoscopy quality assurance programs. Previously, there was no standardised terminology or reporting methods. In 2018, the World Endoscopy Organization (WEO) advised standardised definitions and prevalence calculation methodology.

AIMS

To assess PCCRC burden using WEO standardised methods, to explore causes of heterogeneity, and to review changes in prevalence over time METHODS: We updated a prior systematic review by searching Ovid MEDLINE and EMBASE databases from 1 January 2013 to 31 January 2021 to identify population-based studies (or multicentre studies representative of the local population) reporting PCCRC prevalence (PROSPERO [CRD42020183796]). Two authors independently determined study eligibility, assessed quality, and extracted data. We estimated the PCCRC 3-year prevalence using WEO-recommended methodologies and investigated between-study sources of heterogeneity. We examined changes in prevalence over time.

RESULTS

Fifteen studies reporting on 25 872 PCCRC cases met eligibility criteria. Pooled PCCRC 3 year prevalence was 8.2% (95% CI = 6.9%-9.4%, I²  = 98.2%) across four European studies using WEO precise methodology. Proximal PCCRC prevalence was greater than distal (9.7% [95% CI = 7.0%-12.4%] vs 5.4% [95% CI = 2.9%-7.8%], I²  = 99.2%). Seven studies reporting PCCRC rates over time showed no consistent trend: four showed a decrease, one an increase and two were unchanged. Between-study heterogeneity was high.

CONCLUSIONS

Pooled 3-year PCCRC prevalence was 8.2% (95% CI = 6.9%-9.4%). Despite WEO standardised methodology to define and calculate PCCRC rates, there was significant heterogeneity among studies. Comparing rates between populations remains challenging and additional studies are needed to better understand the global PCCRC burden to inform quality assurance programs.

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.