Who needs colonoscopy to identify colorectal cancer? Bowel symptoms do not add substantially to age and other medical history

Machine Learning for Predicting Colorectal Cancer and Advanced Colorectal Polyps: A Systematic Review and Meta-Analysis

INTRODUCTION

Machine learning (ML) has become increasingly pivotal in health care, particularly in colorectal cancer (CRC) detection and diagnosis with the use of predictive models and artificial intelligence-assisted colonoscopies. This study evaluates the efficacy of ML models in predicting the risk for CRC and advanced colorectal polyps (ACP) before colonoscopy.

METHODS

A systematic literature review was conducted following PRISMA guidelines, focusing on studies using ML for CRC and ACP prediction. Data extraction regarding study type, ML methodology, quality of data, and bias assessment was in line with the CHARMS checklist. Meta-analysis was also performed to assess the performance of models for the prediction of CRC, adenoma, or both.

RESULTS

This systematic review included 14 studies with 3618 median patients (333 to 263,879). Our study demonstrated considerable heterogeneity in methodologies and outcomes, with area under the receiver operating characteristic (AUROC) ranging from 0.6 to 1. The derivation+validation cohorts showed a pooled sensitivity of 0.832 (95% CI: 0.755-0.889) and specificity of 0.802 (95% CI: 0.722-0.863), with an overall AUROC of 0.883.

CONCLUSION

The review underscores the significant role of ML in CRC and ACP diagnosis and its routine use could efficiently direct high-risk patients to timely colonoscopies and spare the low-risk ones from unnecessary procedures. Despite the promise shown, the variability in methodologies and outcomes highlights the need for standardized approaches and further investigation in this field.

Trends in colorectal cancer screening compliance and incidence among 60- to 74-year-olds in China

BACKGROUND

Compliance with colonoscopy among elderly individuals participating in colorectal cancer (CRC) screening programs is unsatisfactory, despite a high detection rate of bowel-related diseases. In this study, our aim was to analyze the impact of risk factors on the trends of compliance and detection rates in colonoscopy among high-risk individuals aged 60-74.

METHODS

A retrospective study was conducted on the high-risk individuals aged 60-74 participating in the 2021 CRC screening program in Tianjin, China. Logistic regression analyses, including both univariate and multivariate analyses, were performed to explore the impact of different risk factors on colonoscopy compliance among the high-risk individuals. Besides, the study investigated the influence of various risk factors on the detection rates of bowel-related diseases among the high-risk individuals who underwent colonoscopy.

RESULTS

A total of 24,064 high-risk individuals were included, and 5478 individuals received a free colonoscopy, with an overall compliance of 22.76%. Among them, the adenoma detection rate was 55.46%. Males and individuals with a positive FIT had high compliance and detection rates for CRC, advanced adenomas (AA), advanced colorectal neoplasia (ACN), and colorectal neoplasm (CN). Individuals aged 70-74 were associated with low compliance but high CRC, ACN, and CN detection rates. Individuals who reported a history of chronic constipation, bloody mucous, and CRC in first-degree relative showed high compliance but no significantwere associated with the detection rates of CRC, AA, and CN.

CONCLUSION

This study reported several risk factors associated with the screening behaviors for CRC. Patterns and trends in CRC, AA, ACN, and CN compliance and detection rates correlate with risk factors.

The performance of FIT-based and other risk prediction models for colorectal neoplasia in symptomatic patients: a systematic review

Background

Colorectal cancer (CRC) incidence and mortality are increasing internationally. Endoscopy services are under significant pressure with many overwhelmed. Faecal immunochemical testing (FIT) has been advocated to identify a high-risk population of symptomatic patients requiring definitive investigation by colonoscopy. Combining FIT with other factors in a risk prediction model could further improve performance in identifying those requiring investigation most urgently. We systematically reviewed performance of models predicting risk of CRC and/or advanced colorectal polyps (ACP) in symptomatic patients, with a particular focus on those models including FIT.

Methods

The review protocol was published on PROSPERO (CRD42022314710). Searches were conducted from database inception to April 2023 in MEDLINE, EMBASE, Cochrane libraries, SCOPUS and CINAHL. Risk of bias of each study was assessed using The Prediction study Risk Of Bias Assessment Tool. A narrative synthesis based on the guidelines for Synthesis Without Meta-Analysis was performed due to study heterogeneity.

Findings

We included 62 studies; 23 included FIT (n = 22) or guaiac Faecal Occult Blood Testing (n = 1) combined with one or more other variables. Twenty-one studies were conducted solely in primary care. Generally, prediction models including FIT consistently had good discriminatory ability for CRC/ACP (i.e. AUC >0.8) and performed better than models without FIT although some models without FIT also performed well. However, many studies did not present calibration and internal and external validation were limited. Two studies were rated as low risk of bias; neither model included FIT.

Interpretation

Risk prediction models, including and not including FIT, show promise for identifying those most at risk of colorectal neoplasia. Substantial limitations in evidence remain, including heterogeneity, high risk of bias, and lack of external validation. Further evaluation in studies adhering to gold standard methodology, in appropriate populations, is required before widespread adoption in clinical practice.

Funding

National Institute for Health and Care Research (NIHR) [Health Technology Assessment Programme (HTA) Programme (Project number 133852).

Development and Validation of Risk Prediction Models for Colorectal Cancer in Patients with Symptoms

We aimed to develop and validate prediction models incorporating demographics, clinical features, and a weighted genetic risk score (wGRS) for individual prediction of colorectal cancer (CRC) risk in patients with gastroenterological symptoms. Prediction models were developed with internal validation [CRC Cases: n = 1686/Controls: n = 963]. Candidate predictors included age, sex, BMI, wGRS, family history, and symptoms (changes in bowel habits, rectal bleeding, weight loss, anaemia, abdominal pain). The baseline model included all the non-genetic predictors. Models A (baseline model + wGRS) and B (baseline model) were developed based on LASSO regression to select predictors. Models C (baseline model + wGRS) and D (baseline model) were built using all variables. Models' calibration and discrimination were evaluated through the Hosmer-Lemeshow test (calibration curves were plotted) and C-statistics (corrected based on 1000 bootstrapping). The models' prediction performance was: model A (corrected C-statistic = 0.765); model B (corrected C-statistic = 0.753); model C (corrected C-statistic = 0.764); and model D (corrected C-statistic = 0.752). Models A and C, that integrated wGRS with demographic and clinical predictors, had a statistically significant improved prediction performance. Our findings suggest that future application of genetic predictors holds significant promise, which could enhance CRC risk prediction. Therefore, further investigation through model external validation and clinical impact is merited.

A risk-stratified approach to colorectal cancer prevention and diagnosis

Population screening and endoscopic surveillance are used widely to prevent the development of and death from colorectal cancer (CRC). However, CRC remains a major cause of cancer mortality and the increasing burden of endoscopic investigations threatens to overwhelm some health services. This Perspective describes the rationale for and approach to improved risk stratification and decision-making for CRC prevention and diagnosis. Limitations of current approaches will be discussed using the UK as an example of the challenges faced by a particular health-care system, followed by discussion of novel risk biomarker utilization. We explore how risk stratification will be advantageous to current health-care providers and users, enabling more efficient use of limited colonoscopy resources. We discuss risk stratification in the setting of population screening as well as the surveillance of high-risk groups and investigation of symptomatic patients. We also address challenges in the development and validation of risk stratification tools and identify key research priorities.

Cancer diagnostic tools to aid decision-making in primary care: mixed-methods systematic reviews and cost-effectiveness analysis

BACKGROUND

Tools based on diagnostic prediction models are available to help general practitioners diagnose cancer. It is unclear whether or not tools expedite diagnosis or affect patient quality of life and/or survival.

OBJECTIVES

The objectives were to evaluate the evidence on the validation, clinical effectiveness, cost-effectiveness, and availability and use of cancer diagnostic tools in primary care.

METHODS

Two systematic reviews were conducted to examine the clinical effectiveness (review 1) and the development, validation and accuracy (review 2) of diagnostic prediction models for aiding general practitioners in cancer diagnosis. Bibliographic searches were conducted on MEDLINE, MEDLINE In-Process, EMBASE, Cochrane Library and Web of Science) in May 2017, with updated searches conducted in November 2018. A decision-analytic model explored the tools' clinical effectiveness and cost-effectiveness in colorectal cancer. The model compared patient outcomes and costs between strategies that included the use of the tools and those that did not, using the NHS perspective. We surveyed 4600 general practitioners in randomly selected UK practices to determine the proportions of general practices and general practitioners with access to, and using, cancer decision support tools. Association between access to these tools and practice-level cancer diagnostic indicators was explored.

RESULTS

Systematic review 1 - five studies, of different design and quality, reporting on three diagnostic tools, were included. We found no evidence that using the tools was associated with better outcomes. Systematic review 2 - 43 studies were included, reporting on prediction models, in various stages of development, for 14 cancer sites (including multiple cancers). Most studies relate to QCancer® (ClinRisk Ltd, Leeds, UK) and risk assessment tools.

DECISION MODEL

In the absence of studies reporting their clinical outcomes, QCancer and risk assessment tools were evaluated against faecal immunochemical testing. A linked data approach was used, which translates diagnostic accuracy into time to diagnosis and treatment, and stage at diagnosis. Given the current lack of evidence, the model showed that the cost-effectiveness of diagnostic tools in colorectal cancer relies on demonstrating patient survival benefits. Sensitivity of faecal immunochemical testing and specificity of QCancer and risk assessment tools in a low-risk population were the key uncertain parameters.

SURVEY

Practitioner- and practice-level response rates were 10.3% (476/4600) and 23.3% (227/975), respectively. Cancer decision support tools were available in 83 out of 227 practices (36.6%, 95% confidence interval 30.3% to 43.1%), and were likely to be used in 38 out of 227 practices (16.7%, 95% confidence interval 12.1% to 22.2%). The mean 2-week-wait referral rate did not differ between practices that do and practices that do not have access to QCancer or risk assessment tools (mean difference of 1.8 referrals per 100,000 referrals, 95% confidence interval -6.7 to 10.3 referrals per 100,000 referrals).

LIMITATIONS

There is little good-quality evidence on the clinical effectiveness and cost-effectiveness of diagnostic tools. Many diagnostic prediction models are limited by a lack of external validation. There are limited data on current UK practice and clinical outcomes of diagnostic strategies, and there is no evidence on the quality-of-life outcomes of diagnostic results. The survey was limited by low response rates.

CONCLUSION

The evidence base on the tools is limited. Research on how general practitioners interact with the tools may help to identify barriers to implementation and uptake, and the potential for clinical effectiveness.

FUTURE WORK

Continued model validation is recommended, especially for risk assessment tools. Assessment of the tools' impact on time to diagnosis and treatment, stage at diagnosis, and health outcomes is also recommended, as is further work to understand how tools are used in general practitioner consultations.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017068373 and CRD42017068375.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology programme and will be published in full in Health Technology Assessment; Vol. 24, No. 66. See the NIHR Journals Library website for further project information.

The yield and patient factors associated with CT colonography C-RADS results in a non-screening patient population

OBJECTIVES

To determine the proportion of diagnostic computed tomography colonography (CTC) Reporting and Data System (C-RADS) categories in a non-screening population, and which patient factors are associated with a positive CTC (C2-4), a non-diagnostic CTC (C0), and potentially relevant extracolonic findings (ECF, E3-4).

METHODS

Diagnostic CTCs performed at a single academic center from 2017 to 2018 were retrospectively reviewed. For each examination, the indications, age, sex, admission status, and C-RADS categories were recorded. Multivariate logistic regression was performed of patient demographic factors and clinical indications, with adjusted odds ratios (OR) and 95% confidence intervals.

RESULTS

1373 CTCs were included. The mean age was 66.4 ± 13 years (range 24-97). There were 782 women and 75 inpatients. The number of CTCs reported as C0-C4 were 194/1373 (14.1%), 970/1373 (70.6%), 77/1373 (5.6%), 86/1373 (6.3%), and 46/1373 (3.4%), respectively, and 134/1373 (9.8%), 960/1373 (69.9%), 173/1373 (12.6%), and 106/1373 (7.7%) CTCs were reported as E1-4, respectively. Factors that demonstrated the strongest associations were as follows: with C2-4, age groups 50-79 (OR 2.8, 95% confidence interval 1.4-6.1), 80-89 (6.2, 2.9-14.5) and ≥ 90 (7.6, 2.0-29.1), and inpatients (3.4, 1.8-6.4); with C0, age groups 50-79 (5.9, 2.2-24.4), 80-89 (9.8, 3.4-41.8), and ≥ 90 (22.5, 5.8-113.0), incomplete colonoscopy (3.2, 2.0-5.1) and melena or gastrointestinal bleeding (4.1, 1.8-9.4); and with E3-4, age groups 50-79 (1.6, 1.0-2.9), 80-89 (2.0, 1.1-3.9), and ≥ 90 (3.2, 1.2-8.8), and inpatients (2.3, 1.3-3.9).

CONCLUSION

Older age is increasingly associated with a positive test, a non-diagnostic test and potentially relevant ECF. Inpatients are also associated with positive tests and E3-4 findings. Symptoms are not strongly associated with a positive CTC.

Evaluating a risk assessment tool to improve triaging of patients to colonoscopies

BACKGROUND

Colonoscopy is the gold standard in the diagnosis of significant bowel disease (SBD), including colorectal cancer, high-risk adenoma and inflammatory bowel disease. As the demand for colonoscopy services is placing significant pressure on hospital resources, new solutions are needed to manage patients more efficiently and effectively.

AIM

We investigated the impact of using a risk assessment tool (RAT) to improve selection of patients for colonoscopy procedures to detect SBD.

METHODS

A hybrid simulation model was constructed to replicate the current patient triage bookings and waiting times in a large metropolitan hospital. The model used data on 327 patients who were retrospectively assessed for risk of SBD. Risk assessment incorporated blood and faecal immunochemical test results, gender and age in addition to patient symptoms. The model was calibrated over 12 months to current outcomes and was compared with the RAT and a third scenario where low-risk patients did not proceed to a colonoscopy. One-way sensitivity analyses were undertaken.

RESULTS

Using the RAT was expected to shorten waiting times by 153 days for moderately-urgent patients and 138 days for non-urgent patients. If low-risk patients did not proceed to colonoscopy, waiting times were expected to reduce for patients with SBD by 17 days producing cost-savings of AU$373 824 through avoided colonoscopies.

CONCLUSIONS

A hybrid model that combines patient-level characteristics with hospital-level resource constraints can demonstrate improved efficiency in a hospital clinic. Further research on risk assessment is required to improve quality patient care and reduce low-value service delivery.

Development and evaluation of a risk assessment tool to improve clinical triage accuracy for colonoscopic investigations

Background

Gastroenterology Departments at hospitals within Australia receive thousands of General Practitioner (GP)-referral letters for gastrointestinal investigations every month. Many of these requests are for colonoscopy. This study aims to evaluate the performance of the current symptoms-based triage system compared to a novel risk score using objective markers.

Methods

Patients with lower abdominal symptoms referred by their GPs and triaged by a Gastroenterology consultant to a colonoscopy consent clinic were recruited into the study. A risk assessment tool (RAT) was developed using objective data (clinical, demographic, pathology (stool test, FIT), standard blood tests and colonoscopy outcome). Colonoscopy and histology results were scored and then stratified as either significant bowel disease (SBD) or non-significant bowel disease (non-SBD).

Results

Of the 467 patients in our study, 45.1% were male, the mean age was 54.3 ± 13.8 years and mean BMI was 27.8 ± 6.2. Overall, 26% had SBD compared to 74% with non-SBD (42% of the cohort had a normal colonoscopy). Increasing severity of referral symptoms was related to a higher triage category, (rectal bleeding, P = 2.86*10^-9; diarrhoea, P = 0.026; abdominal pain, P = 5.67*10^-4). However, there was no significant difference in the prevalence of rectal bleeding (P = 0.991) or diarrhoea (P = 0.843) for SBD. Abdominal pain significantly reduced the risk of SBD (P = 0.0344, OR = 0.52, CI = 0.27-0.95). Conversely, the RAT had a very high specificity of 98% with PPV and NPV of SBD prediction, 74% and 77%, respectively. The RAT provided an odds ratio (OR) of 9.0, 95%CI 4.29-18.75, p = 2.32*10^-11), higher than the FIT test (OR = 5.3, 95%CI 2.44-11.69, p = 4.88*10^-6), blood score (OR = 2.8, 95%CI 1.72- 4.38, p = 1.47*10^-5) or age (OR = 2.5, 95%CI 1.61-4.00, 5.12*10^-5) independently. Notably, the ORs of these individual objective measures were higher than the current practice of symptoms-based triaging (OR = 1.4, 95%CI 0.88-2.11, p = 0.153).

Conclusions

It is critical that individuals with high risk of having SBD are triaged to the appropriate category with the shortest wait time. Here we provide evidence that a combination of blood markers, demographic markers and the FIT test have a higher diagnostic accuracy for SBD than FIT alone.

Published diagnostic models safely excluded colorectal cancer in an independent primary care validation study

OBJECTIVE

To validate published diagnostic models for their ability to safely reduce unnecessary endoscopy referrals in primary care patients suspected of significant colorectal disease.

STUDY DESIGN AND SETTING

Following a systematic literature search, we independently validated the identified diagnostic models in a cross-sectional study of 810 Dutch primary care patients with persistent lower abdominal complaints referred for endoscopy. We estimated diagnostic accuracy measures for colorectal cancer (N = 37) and significant colorectal disease (N = 141; including colorectal cancer, inflammatory bowel disease, diverticulitis, or >1-cm adenomas).

RESULTS

We evaluated 18 models-12 specific for colorectal cancer-, of which most were able to safely rule out colorectal cancer: the best model (National Institute for Health and Care Excellence-1) prevented 59% of referrals (95% confidence interval [CI]: 56-63%), with 96% sensitivity (95% CI: 83-100%), 100% negative predictive value (NPV; 95% CI: 99-100%), and an area under the receiver operating characteristics curve (AUC) of 0.86 (95% CI: 0.80-0.92). The models performed less for significant colorectal disease: the best model (Brazer) prevented 23% of referrals (95% CI: 20-26%), with 95% sensitivity (95% CI: 90-98%), 96% NPV (95% CI: 92-98%), and an AUC of 0.73 (95% CI: 0.69-0.78).

CONCLUSION

Most models safely excluded colorectal cancer in many primary care patients with lower gastrointestinal complaints referred for endoscopy. Models performed less well for significant colorectal disease.

Risk prediction models for colorectal cancer in people with symptoms: a systematic review

Background

Colorectal cancer (CRC) is the fourth leading cause of cancer-related death in Europe and the United States. Detecting the disease at an early stage improves outcomes. Risk prediction models which combine multiple risk factors and symptoms have the potential to improve timely diagnosis. The aim of this review is to systematically identify and compare the performance of models that predict the risk of primary CRC among symptomatic individuals.

Methods

We searched Medline and EMBASE to identify primary research studies reporting, validating or assessing the impact of models. For inclusion, models needed to assess a combination of risk factors that included symptoms, present data on model performance, and be applicable to the general population. Screening of studies for inclusion and data extraction were completed independently by at least two researchers.

Results

Twelve thousand eight hundred eight papers were identified from the literature search and three through citation searching. 18 papers describing 15 risk models were included. Nine were developed in primary care populations and six in secondary care. Four had good discrimination (AUROC > 0.8) in external validation studies, and sensitivity and specificity ranged from 0.25 and 0.99 to 0.99 and 0.46 depending on the cut-off chosen.

Conclusions

Models with good discrimination have been developed in both primary and secondary care populations. Most contain variables that are easily obtainable in a single consultation, but further research is needed to assess clinical utility before they are incorporated into practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0475-7) contains supplementary material, which is available to authorized users.

Validation of the Asia Pacific Colorectal Screening (APCS) score in a Western population: An alternative screening tool

BACKGROUND AND AIM

Colorectal cancer (CRC) screening is based on colonoscopy or fecal occult blood tests, but is imperfect and costly. The Asia Pacific Colorectal Screening Score (APCS) is derived from age, sex, family history of CRC, and smoking history and has been validated in Asian populations. Validation in a Western population is, however, yet to be tested.

METHODS

In a teaching hospital, patients underwent colonoscopy for standard indications and screening over 18 months. Data was collected on age, sex, family history of CRC, smoking, weight, ethnicity, and symptoms. Evaluation of the APCS to predict colonoscopy findings (polyps, adenoma, high risk adenoma, and CRC) was performed.

RESULTS

A total of 645 patients were prospectively recruited (46.7% male, median age 57 years); 17.8% were average risk (AR), 50.9% were moderate risk (MR), and 31.3% high risk (HR) on APCS. High risk adenomas (AA) were seen in 14.9% of the HR, 5.2% MR, and 0.9% LR patients, P < 0.0001. Comparing HR and MR to AR patients demonstrated significantly elevated relative risk (RR) for AA: 17.1 (95% confidence interval [CI] 2.4-123; P = 0.0001), and adenoma 6.0 (0.80-44.3; P = 0.044). Comparing HR to MR groups for AA, the RR was 2.87 (1.62-5.06; P = 0.0001). Symptoms did not predict findings (odds ratio [OR]: 1.06 [0.75-1.48]; P = 0.75). Body mass index (BMI) <20 kg/m(2) was protective against colonic polyps (OR: 0.28, 95%CI: 0.11-0.74; P = 0.010), adenoma (0.08, 0.01-0.62; P = 0.015), and AA (perfect prediction, OR 2.35 × 10(-8)).

CONCLUSIONS

APCS predicts colonic findings in a Western population, to a greater extent than in Asians, independent to symptoms. Low body weight carries a strong protective effect against colonic neoplasia.

Can the colour of per-rectal bleeding estimate the risk of lower gastrointestinal bleeding caused by malignant lesion?

PURPOSE

To estimate the risk of lower gastrointestinal bleeding (LGIB) caused by malignant lesion in patients presenting with per-rectal bleeding (PRB), by using visual aid as an objective measurement of PRB colour.

METHODS

This was a prospective observational study on patients presented with PRB to Family Medicine Specialty Clinic, who undergo flexible sigmoidoscopy (FS) or colonoscopy (CLN) from December 2012 to September 2013. Patients aged 40 years old or above, haemodynamically stable, with normal haemoglobin level were included. Patients with a history of previous colonic surgery, refused to have FS or CLN, with ophthalmologic diseases such as colour blindness were excluded. Parameters including subjective description of PRB colour, number of chosen red colour by patients, source and distance of bleeding from anal verge were recorded for analysis. Receiver operating characteristic (ROC) curve was used to identify the optimal cutoff level of colour for diagnosing colonic lesion. Diagnostic accuracy was assessed by area under the ROC curve (AUC). Accountability of this model was assessed by logistic regression.

RESULTS

The dark PRB colour was associated with diagnosis of tumour (p < 0.001) and advanced neoplastic polyp (p < 0.001). The light PRB colour was associated with the diagnosis of piles (p < 0.001). The performance of our model to predict tumour or advanced neoplastic polyps by colour (AUC, 0.798) had a better discriminative power than that to predict colonic lesion alone (AUC, 0.610) by ROC curve analysis.

CONCLUSION

Objective measurement of PRB colour accurately estimated the risk of LGIB caused by malignant lesion in patients presenting with PRB.

Improving the utility of colonoscopy: Recent advances in practice

Colonoscopy is a frequently performed diagnostic and therapeutic test and the primary screening tool in several nationalized bowel cancer screening programs. There has been a considerable focus on maximizing the utility of colonoscopy. This has occurred in four key areas: Optimizing patient selection to reduce unnecessary or low yield colonoscopy has offered cost-benefit improvements in population screening. Improving quality assurance, through the development of widely accepted quality metrics for use in individual practice and the research setting, has offered measurable improvements in colonoscopic yield. Significant improvements have been demonstrated in colonoscopic technique, from the administration of preparation to the techniques employed during withdrawal of the colonoscope. Improved techniques to avoid post-procedural complications have also been developed-further maximizing the utility of colonoscopy. The aim of this review is to summarize the recent evidence-based advances in colonoscopic practice that contribute to the optimal practice of colonoscopy.

Colorectal cancer diagnosis: Pitfalls and opportunities

Colorectal cancer (CRC) is a major health problem in the Western world. The diagnostic process is a challenge in all health systems for many reasons: There are often no specific symptoms; lower abdominal symptoms are very common and mostly related to non-neoplastic diseases, not CRC; diagnosis of CRC is mainly based on colonoscopy, an invasive procedure; and the resource for diagnosis is usually scarce. Furthermore, the available predictive models for CRC are based on the evaluation of symptoms, and their diagnostic accuracy is limited. Moreover, diagnosis is a complex process involving a sequence of events related to the patient, the initial consulting physician and the health system. Understanding this process is the first step in identifying avoidable factors and reducing the effects of diagnostic delay on the prognosis of CRC. In this article, we describe the predictive value of symptoms for CRC detection. We summarize the available evidence concerning the diagnostic process, as well as the factors implicated in its delay and the methods proposed to reduce it. We describe the different prioritization criteria and predictive models for CRC detection, specifically addressing the two-week wait referral guideline from the National Institute of Clinical Excellence in terms of efficacy, efficiency and diagnostic accuracy. Finally, we collected information on the usefulness of biomarkers, specifically the faecal immunochemical test, as non-invasive diagnostic tests for CRC detection in symptomatic patients.

Findings of diagnostic colonoscopy in young adults versus findings of screening colonoscopy in patients aged 50 to 54 years: a comparative study stratified by symptom category

BACKGROUND

The threshold for diagnostic colonoscopy in symptomatic patients aged <50 years remains controversial. Previous studies on the prevalence of neoplasia or other serious pathology in young patients mostly have been uncontrolled, providing only limited data on the risk associated with specific symptoms.

OBJECTIVE

To compare colonoscopy findings in patients aged <50 years who have various symptoms (diagnostic cohort) against those of concurrent patients aged 50 to 54 years who are asymptomatic (screening cohort).

DESIGN

Retrospective controlled cohort study.

SETTING

Teaching hospital.

PATIENTS

Symptomatic patients aged between 18 and 49 years and asymptomatic patients aged between 50 and 54 years.

INTERVENTIONS

Colonoscopy.

MAIN OUTCOME MEASUREMENTS

Prevalence of advanced neoplasia.

RESULTS

During the study period, 1638 patients underwent colonoscopy in the screening cohort (mean [± standard deviation{SD}] age 51.7 ± 1.4 years) and 1266 underwent colonoscopy in the diagnostic cohort (40.4 ± 8.0 years). Despite the age difference, the prevalence of advanced neoplasia in patients with rectal bleeding was comparable with that in the screening controls: 28 of 472 (5.9%) versus 113 of 1638 patients (6.9%) (P = .459). Furthermore, 10 patients (2.1%) with rectal bleeding were newly diagnosed with inflammatory bowel disease. In contrast, other symptoms that commonly lead to colonoscopy, such as abdominal pain, changes in bowel habits, and weight loss, were associated with much lower risks for neoplasia. As a result, the overall prevalences of neoplasia and advanced neoplasia were significantly higher in the screening cohort than in the diagnostic cohort: 467 of 1638 patients (28.5%) versus 179 of 1266 patients (14.1%), and 113 patients (6.9%) versus 48 patients (3.8%), respectively (both P < .001).

LIMITATIONS

No data on duration of symptoms; discrepant sex ratios between cohorts.

CONCLUSION

The threshold for diagnostic colonoscopy in symptomatic young adults should be individualized for each symptom category. Rectal bleeding warrants colonoscopy to detect advanced neoplasia or inflammatory bowel disease in most young patients, especially those aged 40 to 49 years, whereas non-bleeding symptoms, including some traditionally regarded as "alarm" symptoms, were associated with a much lower risk for neoplasia compared with the risk in screening patients aged 50 to 54 years.

Rising incidence of early-onset colorectal cancer in Australia over two decades: report and review

The average age at diagnosis for colorectal cancer (CRC) in Australia is 69, and the age-specific incidence rises rapidly after age 50 years. The incidence has stabilized or is declining in older age groups in Australia during recent decades, possibly related to the increased uptake of screening and high-risk surveillance. In the same time frame, a rising incidence of CRC in younger adults has been well-documented in the United States. This rise in incidence in the young has not been reported from other countries that share long-term exposure to westernised urban lifestyles. Using data from the Australian Institute of Health and Welfare, we examined trends in national incidence rates for CRC under age 50 years and observed that rates in people under age 40 years have been rising for the last two decades. We further performed a review of the literature regarding CRC in young adults to outline the extent of current understanding, explore potential risk factors such as obesity, alcohol, and sedentary lifestyles, and to identify the questions remaining to be addressed. Although absolute numbers might not justify a population screening approach, the dispersal of young adults with CRC across the primary health-care system decreases probability of their recognition. Patient and physician awareness, aided by stool and emerging blood-screening tests and risk profiling tools, have the potential to aid in identification of those young adults who would most benefit from a colonoscopy through early detection of CRCs or by removal of advanced polyps.

Development of a risk score to stratify symptomatic adults referred for colonoscopy

BACKGROUND AND AIM

With an increasing burden on overstretched colonoscopy services, a simple risk score for significant pathology in symptomatic patients may aid in the prioritization of patients.

METHODS

A derivative study of a risk score model for colonic neoplasia (colorectal carcinoma [CRC] and advanced adenoma) and CRC alone was conducted in symptomatic adults referred for an index colonoscopy. The accuracy of the final model was assessed by the area under the curve (AUC) of the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit statistic.

RESULTS

A total of 1013 subjects (mean age 59.9 ± 13.7 years, 52.3% females) from a multi-ethnic Asian background (Chinese 56%, Malay 20.4%, Indian 21.5%) were recruited. Colonic neoplasia and CRC were identified in 175 (17.3%) and 114 (11.3%) cases, respectively. Risk scores were assigned to individual factors identified in a logistic regression model of both demographic (age, gender, ethnicity, education level, smoking history, Aspirin use) and clinical symptoms (change in bowel habit, bloody stool, weight loss, appetite loss, lethargy). The risk score for each patient was the sum of their individual risk factors. The AUC of the risk score for colonic neoplasia and CRC was 0.76 (Hosmer-Lemeshow goodness-of-fit statistic of P = 0.745) and 0.83 (Hosmer-Lemeshow goodness-of-fit statistic of P = 0.982), respectively.

CONCLUSION

A simple risk score for colonic neoplasia and CRC may be able to prioritize colonoscopy referrals in symptomatic subjects from a multi-ethnic background. A further study to validate this scoring system is required.

Patients who take their symptoms less seriously are more likely to have colorectal cancer

BACKGROUND

People vary in how they respond to symptoms. The purpose of this study was to assess whether serious disease is more likely to be present in patients who report that they take any symptoms less seriously than other people do, and to assess the reliability of a question which can be used to identify the extent to which patients take any symptom seriously. To do this we assessed whether the likelihood of detecting colorectal cancer is higher in patients who report that they take symptoms less seriously than other people do.

METHODS

Cross sectional study of 7736 patients who had colonoscopy to find colorectal cancer. Before colonoscopy, patients completed a questionnaire on bowel symptoms and were also asked: "Compared to other people of your age and sex, how seriously do you think you take any symptoms?" Likelihood of detecting colorectal cancer according to responses to this question was assessed by logistic regression models, unadjusted and adjusted for symptoms and other known predictors of colorectal cancer.Question reliability was assessed in a different sample using percentage agreement and the kappa statistic for the answers given by each patient on two occasions. Agreement between patient and doctor responses was also assessed (n = 108).

RESULTS

Patients who reported they took symptoms less seriously were 3.28 (95%CI: 2.02, 5.33) times more likely to have colorectal cancer than patients who took symptoms more seriously than others. The effect was smaller (1.85 (95%CI: 1.11, 3.09)), but remained statistically significant in models including symptoms and other predictors of colorectal cancer. The question was reliable: on repeat questioning, 70% of responses were in absolute agreement and 92% were within 1 category, kappa 57%. Patient-doctor agreement was 66%, within 1 category 92%, kappa 48%.

CONCLUSION

Patients who take their symptoms less seriously have a considerably higher likelihood of colorectal cancer than those who identify themselves as taking any symptoms more seriously than other people. The question is easy to ask and has good reliability. Doctors also reliably identify how patients assess themselves. Assessment of how seriously patients take any symptoms can contribute to the clinical assessment of a patient.

Cancer risks for relatives of patients with serrated polyposis

OBJECTIVES

Serrated polyposis (hyperplastic polyposis) is characterized by multiple polyps with serrated architecture in the colorectum. Although patients with serrated polyposis are known to be at increased risk of colorectal cancer (CRC) and possibly extracolonic cancers, cancer risk for their relatives has not been widely explored. The aim of this study was to estimate the risks of CRC and extracolonic cancers for relatives of patients with serrated polyposis.

METHODS

A cohort of the 1,639 first- and second-degree relatives of 100 index patients with serrated polyposis recruited regardless of a family history of polyps or cancer from genetic clinics in Australia, New Zealand, Canada, and the USA, were retrospectively analyzed to estimate the country-, age-, and sex-specific standardized incidence ratios (SIRs) for relatives compared with the general population.

RESULTS

A total of 102 CRCs were observed in first- and second-relatives (SIR 2.25, 95% confidence interval (CI) 1.75-2.93; P<0.001), with 54 in first-degree relatives (SIR 5.16, 95% CI 3.70-7.30; P<0.001) and 48 in second-degree relatives (SIR 1.38, 95% CI 1.01-1.91; P=0.04). Six pancreatic cancers were observed in first-degree relatives (SIR 3.64, 95% CI 1.70-9.21; P=0.003). There was no statistical evidence of increased risk for cancer of the stomach, brain, breast, or prostate.

CONCLUSIONS

Our finding that relatives of serrated polyposis patients are at significantly increased risk of colorectal and pancreatic cancer adds to the accumulating evidence that serrated polyposis has an inherited component.

The value of age and medical history for predicting colorectal cancer and adenomas in people referred for colonoscopy

BACKGROUND

Colonoscopy is an invasive and costly procedure with a risk of serious complications. It would therefore be useful to prioritise colonoscopies by identifying people at higher risk of either cancer or premalignant adenomas. The aim of this study is to assess a model that identifies people with colorectal cancer, advanced, large and small adenomas.

METHODS

Patients seen by gastroenterologists and colorectal surgeons between April 2004 and December 2006 completed a validated, structured self-administered questionnaire prior to colonoscopy. Information was collected on symptoms, demographics and medical history. Multinomial logistic regression was used to simultaneously assess factors associated with findings on colonoscopy of cancer, advanced adenomas and adenomas sized 6 -9 mm, and ≤ 5 mm. The area under the curve of ROC curve was used to assess the incremental gain of adding demographic variables, medical history and symptoms (in that order) to a base model that included only age.

RESULTS

Sociodemographic variables, medical history and symptoms (from 8,204 patients) jointly provide good discrimination between colorectal cancer and no abnormality (AUC 0.83), but discriminate less well between adenomas and no abnormality (AUC advanced adenoma 0.70; other adenomas 0.67). Age is the dominant risk factor for cancer and adenomas of all sizes. Having a colonoscopy within the last 10 years confers protection for cancers and advanced adenomas.

CONCLUSIONS

Our models provide guidance about which factors can assist in identifying people at higher risk of disease using easily elicited information. This would allow colonoscopy to be prioritised for those for whom it would be of most benefit.

The role of diagnostic testing in irritable bowel syndrome

This article discusses the diagnostic criteria and processes applicable to irritable bowel syndrome (IBS). The authors describe the various diagnostic criteria with a focus on the Rome criteria for IBS and the judicious application of historical information such as alarm features and the yield of various diagnostic modalities such as blood, stool, breath, and endoscopic tests.