Guaiac faecal occult blood test performance at initial and repeat screens in the English Bowel Cancer Screening Programme

Impact of changes to the interscreening interval and faecal immunochemical test threshold in the national bowel cancer screening programme in England: results from the FIT pilot study

INTRODUCTION

The NHS Bowel Cancer Screening Programme (BCSP) faces endoscopy capacity challenges from the COVID-19 pandemic and plans to lower the screening starting age. This may necessitate modifying the interscreening interval or threshold.

METHODS

We analysed data from the English Faecal Immunochemical Testing (FIT) pilot, comprising 27,238 individuals aged 59-75, screened for colorectal cancer (CRC) using FIT. We estimated screening sensitivity to CRC, adenomas, advanced adenomas (AA) and mean sojourn time of each pathology by faecal haemoglobin (f-Hb) thresholds, then predicted the detection of these abnormalities by interscreening interval and f-Hb threshold.

RESULTS

Current 2-yearly screening with a f-Hb threshold of 120 μg/g was estimated to generate 16,092 colonoscopies, prevent 186 CRCs, detect 1142 CRCs, 7086 adenomas and 4259 AAs per 100,000 screened over 15 years. A higher threshold at 180 μg/g would reduce required colonoscopies to 11,500, prevent 131 CRCs, detect 1077 CRCs, 4961 adenomas and 3184 AAs. A longer interscreening interval of 3 years would reduce required colonoscopies to 10,283, prevent 126 and detect 909 CRCs, 4796 adenomas and 2986 AAs.

CONCLUSION

Increasing the f-Hb threshold was estimated to be more efficient than increasing the interscreening interval regarding overall colonoscopies per screen-benefited cancer. Increasing the interval was more efficient regarding colonoscopies per cancer prevented.

Cost-effectiveness analysis of a community-based colorectal cancer screening program in Shanghai, China

Background

Since 2011, through the Community-Based Colorectal Cancer Screening Program in Shanghai, China (SHcsp), residents aged >50 years were offered initial colorectal cancer screening using the fecal immunochemical test (FIT) and risk assessment questionnaire (RAQ) for free. Colonoscopy was then recommended for positive results.

Objective

To evaluate the cost-effectiveness of the Community-Based Colorectal Cancer Screening Program in Shanghai, China from the payer perspective.

Methods

This analysis estimated the long-term cost and effectiveness of the 2014-2016 SHcsp based on real-world follow-up data from the SHcsp database, Shanghai Cancer Registry System, vital statistics from Shanghai Municipal Center for Disease Control and Prevention and inpatient CRC expense data from hospitals. A decision-tree model and Markov model were constructed to simulate the 25-year health outcomes. The screening branch was the cohort with a definite diagnosis of adenoma, advanced adenoma, and CRC. The other branch was residents who were neither screened nor treated until CRC symptoms appeared. A payer prospective was adopted to measure direct costs and effectiveness by life years (LYs) and quality-adjusted life years (QALYs) gained, and were discounted by 3%. Stimulation robustness was tested by one-way sensitivity analysis.

Results

Of 1,097,656 residents, 13,250 were diagnosed with adenoma, advanced adenoma, or CRC. Assuming those had not been found through screening, SHcsp resulted in 1,570.1 LYs and 13,984.3 QALYs gained at an extra cost of USD9.96 million. The incremental cost-effectiveness ratio (ICER) was USD6,342.02 per LY and USD712.08 per QALY obtained, far below the threshold of USD59,598 of three-time GDP per capita in Shanghai.

Conclusion

The SHcsp was cost-effective than no screening strategy. The results were generalisable to the Chinese population for mass CRC screening.

Optimizing the Design of a Repeated Fecal Immunochemical Test Bowel Cancer Screening Programme With a Limited Endoscopy Capacity From a Health Economic Perspective

OBJECTIVES

In 2016, it was announced that the fecal immunochemical test (FIT) would replace the guaiac fecal occult blood test in the UK Bowel Cancer Screening Programme. England has limited endoscopy capacity. This study informed decision making by determining the most cost-effective FIT screening strategy (age range, frequency, and FIT threshold) under a constrained endoscopy capacity.

METHODS

An economic model with a colorectal cancer natural history component was used to model 60 221 screening strategies with first screening at age 50 to 60 years, screening interval of 1 to 6 years, 3+ screening episodes, and FIT integer threshold of 20 to 180 μg hemoglobin/g feces. Screening strategies requiring the same endoscopy capacity were compared to determine the characteristics of the most cost-effective strategies.

RESULTS

With 50 000 annual screening referral colonoscopies, the 20 most cost-effective strategies had a starting age of 50 to 53 years, 2-yearly screening, 7 or 8 rounds of screening, and FIT threshold of 127 to 166. Compared with a 2-yearly screening interval, screening less frequently (3-, 4-, 5-, or 6-yearly) with a more sensitive FIT was less cost-effective.

CONCLUSIONS

The UK Bowel Cancer Screening Programme should use a 2-yearly FIT screening interval. When endoscopy capacity increases, the screening starting age should be reduced first followed by reducing the FIT threshold. These findings are relevant for other colorectal cancer screening programs with constrained endoscopy capacity.

Health economic studies of colorectal cancer and the contribution of administrative data: A systematic review

INTRODUCTION

Several forces are contributing to an increase in the number of people living with and surviving colorectal cancer (CRC). However, due to the lack of available data, little is known about the implications of these forces. In recent years, the use of administrative records to inform research has been increasing. The aim of this paper is to investigate the potential contribution that administrative data could have on the health economic research of CRC.

METHODS

To achieve this aim, we conducted a systematic review of the health economic CRC literature published in the United Kingdom and Europe within the last decade (2009-2019).

RESULTS

Thirty-seven relevant studies were identified and divided into economic evaluations, cost of illness studies and cost consequence analyses.

CONCLUSIONS

The use of administrative data, including cancer registry, screening and hospital records, within the health economic research of CRC is commonplace. However, we found that this data often come from regional databases, which reduces the generalisability of results. Further, administrative data appear less able to contribute towards understanding the wider and indirect costs associated with the disease. We explore several ways in which various sources of administrative data could enhance future research in this area.

Morbidity and mortality after major large bowel resection of non-malignant polyp among participants in a population-based screening program

Background and aims

Colonoscopy following positive fecal occult blood screening may detect non-malignant polyps deemed to require major large bowel resection. We aimed to estimate the major inpatient morbidity and mortality associated with major resection of non-malignant polyps detected at colonoscopy following positive guaiac fecal occult blood screening in Ontario's population-based colorectal screening program.

Methods

We identified those without a diagnosis of colorectal cancer in the Ontario Cancer Registry ≤24 months following the date of colonoscopy prompted by positive fecal occult blood screening between 2008 and 2017, who underwent a major large bowel resection ≤24 months after the colonoscopy, with a diagnosis code for non-malignant polyp, in the absence of a code for any other large bowel diagnosis. We extracted records of major inpatient complications and readmissions ≤30 days following resection. We computed mortality within 90 days following resection.

Results

For those undergoing colonoscopy ≤6 months following positive guaiac fecal occult blood screening, 420/127,872 (0.03%) underwent major large bowel resection for a non-malignant polyp. In 50/420 (11.9%), the resection included one or more rectosigmoid or rectal polyps, with or without a colonic polyp. There were one or more major inpatient complications or readmissions within 30 days in 117/420 (27.9%). Death occurred within 90 days in 6/420 (1.4%).

Conclusions

Serious inpatient complications and readmissions following major large bowel resection for non-malignant colorectal polyps are common, but mortality ≤90 days following resection is low. These outcomes should be considered as unintended adverse consequences of population-based colorectal screening programs.

Urinary volatile organic compounds and faecal microbiome profiles in colorectal cancer

AIM

Volatile organic compounds (VOCs) are potential biomarkers for diagnosing colorectal cancer (CRC). We characterized urinary VOCs from CRC patients, their spouses/cohabitors (spouses) and first-degree relatives (relatives) to determine any differences. Correlation with stool-derived microbiomes was also undertaken.

METHODS

Urine from 56 CRC patients, 45 spouses and 37 relatives was assayed using liquid chromatography, field asymmetric ion mobility spectrometry (FAIMS), mass spectrometer technology. Analysis was performed using five-fold cross-validation and a random forest classifier. Faecal microbiome 16S rRNA was sequenced using Illumina MiSeq protocols and analysed using UPARSE and QIIME pipelines. VOC and microbiome profiles were also compared before and after cancer treatment.

RESULTS

Urinary VOC profiles of CRC patients were indistinguishable from either spouses or relatives. When spouses and relatives were grouped together to form a larger non-cancer control group (n = 82), their VOC profiles became distinguishable from those of CRC patients (n = 56) with 69% sensitivity and specificity, area under the curve 0.72 (P < 0.001). Microbiome analysis identified > 1300 operational taxonomic units across all groups. The analysis of similarity R value was 0.067 (P < 0.001), with significantly different bacterial abundances in 82 operational taxonomic units (6.2%) by Kruskal-Wallis testing. CRC patients' VOC or stool microbiome profiles were unchanged after treatment.

CONCLUSION

Although CRC patients' urinary VOC profiles cannot be differentiated from those of spouses or relatives they can be differentiated from a larger non-cancer control group. Comparison of the groups' microbiomes confirmed differences in bacterial species abundance. The current FAIMS-based assay can detect a unique, but modest, signal in CRC patients' urinary VOCs, which remains unaltered after treatment.

External Validation of a Colorectal Cancer Model Against Screening Trial Long-Term Follow-Up Data

BACKGROUND

The University of Sheffield School of Health and Related Research (ScHARR) Bowel Cancer Screening Model has been used previously to make decisions about colorectal cancer screening strategies in England.

OBJECTIVES

The objective of this study was to perform an external validation of the ScHARR model against long-term follow-up data about colorectal cancer (CRC) incidence and mortality reductions due to screening, from the Nottingham trial of guaiac faecal occult blood testing for CRC, and the UK Flexible Sigmoidoscopy Screening Trial.

METHODS

The ScHARR model was adapted prior to validation to reflect the setting of each trial in terms of population characteristics, details of screening and surveillance programs, uptake of screening, and further investigations and study follow-up. The impact of using current versus historical CRC incidence and mortality data in the validation was also examined by carrying out a series of analyses in which historical data from different years was included in the model.

RESULTS

The ScHARR model was able to predict CRC incidence and mortality rate/hazard ratios from both trials to well within the 95% confidence intervals in the observed data. While it was less accurate in predicting absolute incidence and mortality rates, modeling historical incidence and mortality data enabled these predictions to be improved considerably.

CONCLUSION

The ScHARR model is able to replicate the long-term relative benefit from screening observed in 2 large-scale UK-based screening trials and can therefore be considered to be an appropriate tool to facilitate decision making around the English bowel cancer screening program.

Switching from guaiac to immunochemical faecal occult blood test increases participation and diagnostic yield of colorectal cancer screening

BACKGROUND

Compared with the guaiac-faecal occult blood test (gFOBT), faecal immunological tests (FIT) are considered to be more effective for colorectal cancer (CRC) screening. However, only scarce research has examined the outcomes of switching to FIT within a mature gFOBT-based CRC screening programme.

METHODS

We reported a 15-year experience of biennial FOBT screening in a well-defined population of approximately one million inhabitants, including six gFOBT-based screening rounds and one round with FIT at the 30 μg Hb/g cut-off. The main outcome measures were screening participation, FOBT positivity and advanced neoplasia detection in each round.

RESULTS

In this study, 647 676 screenings were performed in 228 716 different individuals, leading to 17 819 positives and 16 580 follow-up colonoscopies. Compared with the last gFOBT round, switching to FIT led to an increased participation of nearly 20% points, and a fivefold increased detection of CRC and advanced adenoma among invitees (3-fold among attendees). The numbers needed to screen and scope to detect one advanced neoplasia declined from 221 to 66 and from 4.7 to 2.6, respectively.

CONCLUSIONS

The present population-based study demonstrated a dramatical increase in the diagnostic yield of advanced neoplasia by switching to FIT within a mature gFOBT-based CRC screening programme.

Association of ten gastrointestinal and other medical conditions with positivity to faecal occult blood testing in routine screening: a large prospective study of women in England

BACKGROUND

In 2006, the Bowel Cancer Screening Programme (BCSP) in England began offering biennial faecal occult blood testing (FOBt) at ages 60-69 years. Although FOBt is aimed at detecting colorectal neoplasms, other conditions can affect the result. In a large UK prospective study, we examined associations, both before and after screening, between FOBt positivity and 10 conditions that are often associated with gastrointestinal bleeding.

METHODS

By electronically linking BCSP and Million Women Study records, we identified 604 495 women without previous colorectal cancer who participated in their first routine FOBt screening between 2006 and 2012. Regression models, using linked national hospital admission records, yielded adjusted relative risks (RRs) in FOBt-positive versus FOBt-negative women for colorectal cancer, adenoma, diverticular disease, inflammatory bowel disease, haemorrhoids, upper gastrointestinal cancer, oesophagitis, peptic ulcer, anaemia and other haematological disorders.

RESULTS

RRs in FOBt-positive versus FOBt-negative women were 201.3 (95% CI 173.8-233.2) for colorectal cancer and 197.9 (95% CI 180.6-216.8) for adenoma within 12 months after screening and 3.49 (95% CI 2.31-5.26) and 4.88 (95% CI 3.80-6.26), respectively, 12-24 months after screening; P < 0.001 for all RRs. In the 12 months after screening, the RR for inflammatory bowel disease was 26.3 (95% CI 19.9-34.7), and ranged between 2 and 5 for the upper gastrointestinal or haematological disorders. The RRs of being diagnosed with any of the eight conditions other than colorectal neoplasms before screening, and in the 12-24 months after screening, were 1.81 (95% CI 1.81-2.01) and 1.92 (95% CI 1.66-2.13), respectively.

CONCLUSIONS

Whereas FOBt positivity is associated with a substantially increased risk of colorectal neoplasms after screening, eight other gastrointestinal and haematological conditions are also associated with FOBt positivity, both before and after screening.

Critical Analysis of Markov Models Used for the Economic Evaluation of Colorectal Cancer Screening: A Systematic Review

BACKGROUND

The economic evaluation of colorectal cancer screening is challenging because of the need to model the underlying unobservable natural history of the disease.

OBJECTIVES

To describe the available Markov models and to critically analyze their main structural assumptions.

METHODS

A systematic search was performed in eight relevant databases (MEDLINE, Embase, Econlit, National Health Service Economic Evaluation Database, Health Economic Evaluations Database, Health Technology Assessment database, Cost-Effective Analysis Registry, and European Network of Health Economics Evaluation Databases), identifying 34 models that met the inclusion criteria. A comparative analysis of model structure and parameterization was conducted using two checklists and guidelines for cost-effectiveness screening models.

RESULTS

Two modeling techniques were identified. One strategy used a Markov model to reproduce the natural history of the disease and an overlaying model that reproduced the screening process, whereas the other used a single model to represent a screening program. Most of the studies included only adenoma-carcinoma sequences, a few included de novo cancer, and none included the serrated pathway. Parameterization of adenoma dwell time, sojourn time, and surveillance differed between studies, and there was a lack of validation and statistical calibration against local epidemiological data. Most of the studies analyzed failed to perform an adequate literature review and synthesis of diagnostic accuracy properties of the screening tests modeled.

CONCLUSIONS

Several strategies to model colorectal cancer screening have been developed, but many challenges remain to adequately represent the natural history of the disease and the screening process. Structural uncertainty analysis could be a useful strategy for understanding the impact of the assumptions of different models on cost-effectiveness results.

The association between long-term conditions and uptake of population-based screening for colorectal cancer: results from two English cohort studies

Introduction

Uptake of screening for colorectal cancer (CRC) can reduce mortality, and population-based screening is offered in England. To date, there is little evidence on the association between having a long-term condition (LTC) and CRC screening uptake. The objective of this study was to examine the association between having an LTC and uptake of CRC screening in England with the guaiac fecal occult blood test, with a particular focus on common mental disorders.

Methods

The study was a preregistered secondary analysis of two cohorts: first, a linked data set between the regional Yorkshire Health Study (YHS) and the National Health Service National Bowel Cancer Screening Program (BCSP, years 2006–2014); second, the national English Longitudinal Study of Ageing (ELSA, years 2014–2015). Individuals eligible for BCSP screening who participated in either the YHS (7,142) or ELSA Wave 7 (4,099) were included. Study registration: ClinicalTrials.gov, number NCT02503969.

Results

In both the cohorts, diabetes was associated with lower uptake (YHS odds ratio [OR] for non-uptake 1.35, 95% CI 1.03–1.78; ELSA 1.33, 1.03–1.72) and osteoarthritis was associated with increased uptake (YHS 0.75, 0.57–0.99; ELSA 0.76, 0.62–0.93). After controlling for broader determinants of health, there was no evidence of significantly different uptake for individuals with common mental disorders.

Conclusion

Two large independent cohorts provided evidence that uptake of CRC screening is lower among individuals with diabetes and higher among individuals with osteoarthritis. Further work should compare barriers and facilitators to screening among individuals with either of these conditions. This study also demonstrates the benefits of data linkage for improving clinical decision-making.

The clinical effectiveness of different surveillance strategies to prevent colorectal cancer in people with intermediate-grade colorectal adenomas: a retrospective cohort analysis, and psychological and economic evaluations

BACKGROUND

The UK guideline recommends 3-yearly surveillance for patients with intermediate-risk (IR) adenomas. No study has examined whether or not this group has heterogeneity in surveillance needs.

OBJECTIVES

To examine the effect of surveillance on colorectal cancer (CRC) incidence; assess heterogeneity in risk; and identify the optimum frequency of surveillance, the psychological impact of surveillance, and the cost-effectiveness of alternative follow-up strategies.

DESIGN

Retrospective multicentre cohort study.

SETTING

Routine endoscopy and pathology data from 17 UK hospitals (n = 11,944), and a screening data set comprising three pooled cohorts (n = 2352), followed up using cancer registries.

SUBJECTS

Patients with IR adenoma(s) (three or four small adenomas or one or two large adenomas).

PRIMARY OUTCOMES

Advanced adenoma (AA) and CRC detected at follow-up visits, and CRC incidence after baseline and first follow-up.

METHODS

The effects of surveillance on long-term CRC incidence and of interval length on findings at follow-up were examined using proportional hazards and logistic regression, adjusting for patient, procedural and polyp characteristics. Lower-intermediate-risk (LIR) subgroups and higher-intermediate-risk (HIR) subgroups were defined, based on predictors of CRC risk. A model-based cost-utility analysis compared 13 surveillance strategies. Between-group analyses of variance were used to test for differences in bowel cancer worry between screening outcome groups (n = 35,700). A limitation of using routine hospital data is the potential for missed examinations and underestimation of the effect of interval and surveillance.

RESULTS

In the hospital data set, 168 CRCs occurred during 81,442 person-years (pys) of follow-up [206 per 100,000 pys, 95% confidence interval (CI) 177 to 240 pys]. One surveillance significantly lowered CRC incidence, both overall [hazard ratio (HR) 0.51, 95% CI 0.34 to 0.77] and in the HIR subgroup (n = 9265; HR 0.50, 95% CI 0.34 to 0.76). In the LIR subgroup (n = 2679) the benefit of surveillance was less clear (HR 0.62, 95% CI 0.16 to 2.43). Additional surveillance lowered CRC risk in the HIR subgroup by a further 15% (HR 0.36, 95% CI 0.20 to 0.62). The odds of detecting AA and CRC at first follow-up (FUV1) increased by 18% [odds ratio (OR) 1.18, 95% CI 1.12 to 1.24] and 32% (OR 1.32, 95% CI 1.20 to 1.46) per year increase in interval, respectively, and the odds of advanced neoplasia at second follow-up increased by 22% (OR 1.22, 95% CI 1.09 to 1.36), after adjustment. Detection rates of AA and CRC remained below 10% and 1%, respectively, with intervals to 3 years. In the screening data set, 32 CRCs occurred during 25,745 pys of follow-up (124 per 100,000 pys, 95% CI 88 to 176 pys). One follow-up conferred a significant 73% reduction in CRC incidence (HR 0.27, 95% CI 0.10 to 0.71). Owing to the small number of end points in this data set, no other outcome was significant. Although post-screening bowel cancer worry was higher in people who were offered surveillance, worry was due to polyp detection rather than surveillance. The economic evaluation, using data from the hospital data set, suggested that 3-yearly colonoscopic surveillance without an age cut-off would produce the greatest health gain.

CONCLUSIONS

A single surveillance benefited all IR patients by lowering their CRC risk. We identified a higher-risk subgroup that benefited from further surveillance, and a lower-risk subgroup that may require only one follow-up. A surveillance interval of 3 years seems suitable for most IR patients. These findings should be validated in other studies to confirm whether or not one surveillance visit provides adequate protection for the lower-risk subgroup of intermediate-risk patients.

STUDY REGISTRATION

Current Controlled Trials ISRCTN15213649.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Defining and measuring adherence to cancer screening

BACKGROUND

The importance of cancer screening is well-recognized, yet there is great variation in how adherence is defined and measured. This manuscript identifies measures of screening adherence and discusses how to estimate them.

DISCUSSION

We begin by describing why screening adherence is of interest: to anticipate long-term outcomes, to understand differences in outcomes across settings, and to identify areas for improvement. We outline questions of interest related to adherence, including questions about uptake, currency or being up-to-date, and longitudinal adherence, and then identify which measures are most appropriate for each question. Our discussion of how to select measures focuses on study inclusion criteria and outcome definitions. Finally, we describe how to estimate different measures using data from two common data sources: survey studies and surveillance studies. Estimation requires consideration of data sources, inclusion criteria, and outcome definitions. Censoring often will be present and must be accounted for.

CONCLUSION

We conclude that consistent definitions and estimation of adherence to cancer screening guidelines will facilitate comparison across studies, tests, and settings, and help to elucidate areas for future research and intervention.

Factors associated with completion of bowel cancer screening and the potential effects of simplifying the screening test algorithm

Background:

The primary colorectal cancer screening test in England is a guaiac faecal occult blood test (gFOBt). The NHS Bowel Cancer Screening Programme (BCSP) interprets tests on six samples on up to three test kits to determine a definitive positive or negative result. However, the test algorithm fails to achieve a definitive result for a significant number of participants because they do not comply with the programme requirements. This study identifies factors associated with failed compliance and modifications to the screening algorithm that will improve the clinical effectiveness of the screening programme.

Methods:

The BCSP Southern Hub data for screening episodes started in 2006–2012 were analysed for participants aged 60–69 years. The variables included age, sex, level of deprivation, gFOBt results and clinical outcome.

Results:

The data set included 1 409 335 screening episodes; 95.08% of participants had a definitively normal result on kit 1 (no positive spots). Among participants asked to complete a second or third gFOBt, 5.10% and 4.65%, respectively, failed to return a valid kit. Among participants referred for follow up, 13.80% did not comply. Older age was associated with compliance at repeat testing, but non-compliance at follow up. Increasing levels of deprivation were associated with non-compliance at repeat testing and follow up. Modelling a reduction in the threshold for immediate referral led to a small increase in completion of the screening pathway.

Conclusions:

Reducing the number of positive spots required on the first gFOBt kit for referral for follow-up and targeted measures to improve compliance with follow-up may improve completion of the screening pathway.