A combination of clinical risk stratification and fecal immunochemical test results to prioritize colonoscopy screening in asymptomatic participants

Developing a Nomogram for Predicting Colorectal Cancer and Its Precancerous Lesions Based on Data from Three Non-Invasive Screening Tools, APCS, FIT, and sDNA

Purpose

This study aimed to develop and validate a nomogram for predicting positive colonoscopy results using the data from non-invasive screening strategies.

Methods

The volunteers participated in primary colorectal cancer (CRC) screenings using Asia-Pacific colorectal screening (APCS) scoring, faecal immunochemical testing (FIT) and stool deoxyribonucleic acid (sDNA) testing and underwent a colonoscopy. The positive colonoscopy results included CRC, advanced adenoma (AA), high-grade intraepithelial neoplasia (HGIN), and low-grade intraepithelial neoplasia (LGIN). The enrolled participants were randomly selected for training and validation sets in a 7:3 ratio. A model for predicting positive colonoscopy results was virtualized by the nomogram using logistic regression analysis.

Results

Among the 179 enrolled participants, 125 were assigned to training set, while 54 were assigned to validation set. After multivariable logistic regression was done, APCS score, FIT result, and sDNA result were all identified as the predictors for positive colonoscopy results. A model that incorporated the above independent predictors was developed and presented as a nomogram. The C-index of the nomogram in the validation set was 0.768 (95% CI, 0.644-0.891). The calibration curve demonstrated a good agreement between prediction and observation. The decision curve analysis (DCA) curve showed that the model achieved a net benefit across all threshold probabilities. The AUC of the prediction model for predicting positive colonoscopy results was much higher than that of the FIT + sDNA test scheme.

Conclusion

The nomogram for predicting positive colonoscopy results was successfully developed based on 3 non-invasive screening tools (APCS scoring, FIT and sDNA test).

Performance of the Asia-Pacific Colorectal Screening score in stratifying the risk of advanced colorectal neoplasia: A meta-analysis and systematic review

BACKGROUND AND AIM

This study systematically reviewed and meta-analyzed the performance of the Asia-Pacific Colorectal Screening (APCS) score and its incorporation with the fecal immunochemical test (FIT) in stratifying the risk of advanced colorectal neoplasia (ACN).

METHODS

We systematically searched for relevant articles in 12 electronic databases and registers on October 20, 2021, and updated the search to September 1, 2023. Random-effect models were used to obtain the pooled performance statistics of the APCS score for ACN risk.

RESULTS

From the 101 records screened, 13 eligible studies in the Asia-Pacific region involving 69 762 subjects who had undergone colonoscopy were enrolled. The pooled prevalences of ACN in the average-risk (AR) tier (APCS 0-1), moderate-risk (MR) tier (APCS 2-3), and high-risk (HR) tier (APCS ≥ 4) groups were 0.9%, 3.1%, and 8.1%, respectively. Compared with the combined AR-MR group, the HR group was significantly associated with a higher ACN risk (pooled diagnostic odds ratio: 2.84, 95% confidence interval [CI]: 2.35-3.45, P < 0.001). The APCS score showed a sensitivity of 0.42 (95% CI: 0.40-0.44) and a specificity of 0.86 (95% CI: 0.85-0.86) for predicting the ACN risk, with a weighted area under the curve of 0.642 (95% CI: 0.610-0.657). The combination of the APCS score and FIT substantially improved ACN risk identification, demonstrating pooled diagnostic odds ratios of 4.02 (95% CI: 2.50-6.49) in the AR-MR groups and 5.44 (95% CI: 1.89-15.63) in the MR-HR groups.

CONCLUSIONS

The APCS score could effectively stratify the ACN risk in the Asia-Pacific population. Incorporating FIT further improves its performance in identifying high-risk subjects who should be prioritized for colonoscopy screenings.

Colorectal Cancer: Epidemiology, Risk Factors, and Prevention

Colorectal cancer (CRC) is the third most common cancer and the second most common cause of cancer mortality worldwide. There are disparities in the epidemiology of CRC across different populations, most probably due to differences in exposure to lifestyle and environmental factors related to CRC. Prevention is the most effective method for controlling CRC. Primary prevention includes determining and avoiding modifiable risk factors (e.g., alcohol consumption, smoking, and dietary factors) as well as increasing protective factors (e.g., physical activity, aspirin). Further studies, especially randomized, controlled trials, are needed to clarify the association between CRC incidence and exposure to different risk factors or protective factors. Detection and removal of precancerous colorectal lesions is also an effective strategy for controlling CRC. Multiple factors, both at the individual and community levels (e.g., patient preferences, availability of screening modalities, costs, benefits, and adverse events), should be taken into account in designing and implementing CRC screening programs. Health policymakers should consider the best decision in identifying the starting age and selection of the most effective screening strategies for the target population. This review aims to present updated evidence on the epidemiology, risk factors, and prevention of CRC.

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.

Colorectal Cancer Risk Assessment and Precision Approaches to Screening: Brave New World or Worlds Apart?

Current colorectal cancer (CRC) screening recommendations take a "one-size-fits-all" approach using age as the major criterion to initiate screening. Precision screening that incorporates factors beyond age to risk stratify individuals could improve on current approaches and optimally use available resources with benefits for patients, providers, and health care systems. Prediction models could identify high-risk groups who would benefit from more intensive screening, while low-risk groups could be recommended less intensive screening incorporating noninvasive screening modalities. In addition to age, prediction models incorporate well-established risk factors such as genetics (eg, family CRC history, germline, and polygenic risk scores), lifestyle (eg, smoking, alcohol, diet, and physical inactivity), sex, and race and ethnicity among others. Although several risk prediction models have been validated, few have been systematically studied for risk-adapted population CRC screening. In order to envisage clinical implementation of precision screening in the future, it will be critical to develop reliable and accurate prediction models that apply to all individuals in a population; prospectively study risk-adapted CRC screening on the population level; garner acceptance from patients and providers; and assess feasibility, resources, cost, and cost-effectiveness of these new paradigms. This review evaluates the current state of risk prediction modeling and provides a roadmap for future implementation of precision CRC screening.

Third Asia-Pacific consensus recommendations on colorectal cancer screening and postpolypectomy surveillance

The Asia-Pacific region has the largest number of cases of colorectal cancer (CRC) and one of the highest levels of mortality due to this condition in the world. Since the publishing of two consensus recommendations in 2008 and 2015, significant advancements have been made in our knowledge of epidemiology, pathology and the natural history of the adenoma-carcinoma progression. Based on the most updated epidemiological and clinical studies in this region, considering literature from international studies, and adopting the modified Delphi process, the Asia-Pacific Working Group on Colorectal Cancer Screening has updated and revised their recommendations on (1) screening methods and preferred strategies; (2) age for starting and terminating screening for CRC; (3) screening for individuals with a family history of CRC or advanced adenoma; (4) surveillance for those with adenomas; (5) screening and surveillance for sessile serrated lesions and (6) quality assurance of screening programmes. Thirteen countries/regions in the Asia-Pacific region were represented in this exercise. International advisors from North America and Europe were invited to participate.

Combined performance of fecal immunochemical tests and a genetic risk score for advanced neoplasia detection

Fecal immunochemical tests (FITs) are increasingly used as noninvasive screening tests in colorectal cancer (CRC) screening programs. Polygenic risk scores (PRS) are increasingly propagated for risk stratification in CRC screening. We aimed to assess the potential of combining FIT results and PRS to enhance diagnostic accuracy of detecting advanced neoplasia (AN) compared to using FIT results alone. Of 10,362 participants of screening colonoscopy in Southern Germany who conducted either one of two quantitative FITs, genotyping was done in all participants with advanced neoplasia (CRC or advanced adenoma) and a random subset of controls. Among 5,306 individuals, a PRS was calculated based on the number of risk alleles in 140 single nucleotide polymorphisms. Partial areas under the receiver operating characteristics (ROC) curves (pAUCs) were computed for FIT and PRS alone and combined, focusing on a specificity range of 100%-80%. Both FITs showed similar performance characteristics with pAUCs (95%CIs) of 0.661 (0.625-0.698) (Ridascreen Hemoglobin) and 0.682 (0.661-0.701) (FOB Gold) for AN detection. PRS alone reached a pAUC (95%CI) of 0.524 (0.499-0.550) and 0.530 (0.516-0.545), respectively, and its addition to FIT did not improve pAUCs (0.659 (0.622-0.697) and 0.667 (0.650-0.687), respectively). This finding was confirmed by investigating sensitivities at fixed specificities at 85%, 90% and 95%. Partial AUCs also did not improve when adding the weighted PRS to FIT instead of the unweighted PRS. In summary, the combination with PRS did not improve diagnostic accuracy of FIT-based screening in a large asymptomatic CRC screening population from South-Western Germany.

Guaiac-based faecal occult blood tests versus faecal immunochemical tests for colorectal cancer screening in average-risk individuals

BACKGROUND

Worldwide, many countries have adopted colorectal cancer (CRC) screening programmes, often based on faecal occult blood tests (FOBTs). CRC screening aims to detect advanced neoplasia (AN), which is defined as CRC or advanced adenomas. FOBTs fall into two categories based on detection technique and the detected blood component: qualitative guaiac-based FOBTs (gFOBTs) and faecal immunochemical tests (FITs), which can be qualitative and quantitative. Screening with gFOBTs reduces CRC-related mortality.

OBJECTIVES

To compare the diagnostic test accuracy of gFOBT and FIT screening for detecting advanced colorectal neoplasia in average-risk individuals.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, BIOSIS Citation Index, Science Citation Index Expanded, and Google Scholar. We searched the reference lists and PubMed-related articles of included studies to identify additional studies.

SELECTION CRITERIA

We included prospective and retrospective studies that provided the number of true positives, false positives, false negatives, and true negatives for gFOBTs, FITs, or both, with colonoscopy as reference standard. We excluded case-control studies. We included studies in which all participants underwent both index test and reference standard ("reference standard: all"), and studies in which only participants with a positive index test underwent the reference standard while participants with a negative test were followed for at least one year for development of interval carcinomas ("reference standard: positive"). The target population consisted of asymptomatic, average-risk individuals undergoing CRC screening. The target conditions were CRC and advanced neoplasia (advanced adenomas and CRC combined).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected studies for inclusion. In case of disagreement, a third review author made the final decision. We used the Rutter and Gatsonis hierarchical summary receiver operating characteristic model to explore differences between tests and identify potential sources of heterogeneity, and the bivariate hierarchical model to estimate sensitivity and specificity at common thresholds: 10 µg haemoglobin (Hb)/g faeces and 20 µg Hb/g faeces. We performed indirect comparisons of the accuracy of the two tests and direct comparisons when both index tests were evaluated in the same population.

MAIN RESULTS

We ran the initial search on 25 June 2019, which yielded 63 studies for inclusion. We ran a top-up search on 14 September 2021, which yielded one potentially eligible study, currently awaiting classification. We included a total of 33 "reference standard: all" published articles involving 104,640 participants. Six studies evaluated only gFOBTs, 23 studies evaluated only FITs, and four studies included both gFOBTs and FITs. The cut-off for positivity of FITs varied between 2.4 μg and 50 µg Hb/g faeces. For each Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 domain, we assessed risk of bias as high in less than 20% of studies. The summary curve showed that FITs had a higher discriminative ability than gFOBTs for AN (P < 0.001) and CRC (P = 0.004). For the detection of AN, the summary sensitivity of gFOBTs was 15% (95% confidence interval (CI) 12% to 20%), which was significantly lower than FITs at both 10 μg and 20 μg Hb/g cut-offs with summary sensitivities of 33% (95% CI 27% to 40%; P < 0.001) and 26% (95% CI 21% to 31%, P = 0.002), respectively. Results were simulated in a hypothetical cohort of 10,000 screening participants with 1% CRC prevalence and 10% AN prevalence. Out of 1000 participants with AN, gFOBTs missed 850, while FITs missed 670 (10 μg Hb/g cut-off) and 740 (20 μg Hb/g cut-off). No significant differences in summary specificity for AN detection were found between gFOBTs (94%; 95% CI 92% to 96%), and FITs at 10 μg Hb/g cut-off (93%; 95% CI 90% to 95%) and at 20 μg Hb/g cut-off (97%; 95% CI 95% to 98%). So, among 9000 participants without AN, 540 were offered (unnecessary) colonoscopy with gFOBTs compared to 630 (10 μg Hb/g) and 270 (20 μg Hb/g) with FITs. Similarly, for the detection of CRC, the summary sensitivity of gFOBTs, 39% (95% CI 25% to 55%), was significantly lower than FITs at 10 μg and 20 μg Hb/g cut-offs: 76% (95% CI 57% to 88%: P = 0.001) and 65% (95% CI 46% to 80%; P = 0.035), respectively. So, out of 100 participants with CRC, gFOBTs missed 61, and FITs missed 24 (10 μg Hb/g) and 35 (20 μg Hb/g). No significant differences in summary specificity for CRC were found between gFOBTs (94%; 95% CI 91% to 96%), and FITs at the 10 μg Hb/g cut-off (94%; 95% CI 87% to 97%) and 20 μg Hb/g cut-off (96%; 95% CI 91% to 98%). So, out of 9900 participants without CRC, 594 were offered (unnecessary) colonoscopy with gFOBTs versus 594 (10 μg Hb/g) and 396 (20 μg Hb/g) with FITs. In five studies that compared FITs and gFOBTs in the same population, FITs showed a higher discriminative ability for AN than gFOBTs (P = 0.003). We included a total of 30 "reference standard: positive" studies involving 3,664,934 participants. Of these, eight were gFOBT-only studies, 18 were FIT-only studies, and four studies combined both gFOBTs and FITs. The cut-off for positivity of FITs varied between 5 µg to 250 µg Hb/g faeces. For each QUADAS-2 domain, we assessed risk of bias as high in less than 20% of studies. The summary curve showed that FITs had a higher discriminative ability for detecting CRC than gFOBTs (P < 0.001). The summary sensitivity for CRC of gFOBTs, 59% (95% CI 55% to 64%), was significantly lower than FITs at the 10 μg Hb/g cut-off, 89% (95% CI 80% to 95%; P < 0.001) and the 20 μg Hb/g cut-off, 89% (95% CI 85% to 92%; P < 0.001). So, in the hypothetical cohort with 100 participants with CRC, gFOBTs missed 41, while FITs missed 11 (10 μg Hb/g) and 11 (20 μg Hb/g). The summary specificity of gFOBTs was 98% (95% CI 98% to 99%), which was higher than FITs at both 10 μg and 20 μg Hb/g cut-offs: 94% (95% CI 92% to 95%; P < 0.001) and 95% (95% CI 94% to 96%; P < 0.001), respectively. So, out of 9900 participants without CRC, 198 were offered (unnecessary) colonoscopy with gFOBTs compared to 594 (10 μg Hb/g) and 495 (20 μg Hb/g) with FITs. At a specificity of 90% and 95%, FITs had a higher sensitivity than gFOBTs.

AUTHORS' CONCLUSIONS

FITs are superior to gFOBTs in detecting AN and CRC in average-risk individuals. Specificity of both tests was similar in "reference standard: all" studies, whereas specificity was significantly higher for gFOBTs than FITs in "reference standard: positive" studies. However, at pre-specified specificities, the sensitivity of FITs was significantly higher than gFOBTs.

A scoping review of risk-stratified bowel screening: current evidence, future directions

PURPOSE

In this scoping review, we examined the international literature on risk-stratified bowel screening to develop recommendations for future research, practice and policy.

METHODS

Six electronic databases were searched from inception to 18 October 2021: Medline, Embase, PsycINFO, CINAHL, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials. Forward and backwards citation searches were also undertaken. All relevant literature were included.

RESULTS

After de-deduplication, 3,629 records remained. 3,416 were excluded at the title/abstract screening stage. A further 111 were excluded at full-text screening stage. In total, 102 unique studies were included. Results showed that risk-stratified bowel screening programmes can potentially improve diagnostic performance, but there is a lack of information on longer-term outcomes. Risk models do appear to show promise in refining existing risk stratification guidelines but most were not externally validated and less than half achieved good discriminatory power. Risk assessment tools in primary care have the potential for high levels of acceptability and uptake, and therefore, could form an important component of future risk-stratified bowel screening programmes, but sometimes the screening recommendations were not adhered to by the patient or healthcare provider. The review identified important knowledge gaps, most notably in the area of organisation of screening services due to few pilots, and what risk stratification might mean for inequalities.

CONCLUSION

We recommend that future research focuses on what organisational challenges risk-stratified bowel screening may face and a consideration of inequalities in any changes to organised bowel screening programmes.

Comparative yield and efficiency of strategies based on risk assessment and fecal immunochemical test in colorectal cancer screening: A cross-sectional population-based analysis

Objective

Integration of risk stratification into fecal immunochemical test (FIT) might aid in the suboptimal detection of advanced neoplasms by FIT in colorectal cancer (CRC) screening. A comparative study was conducted to evaluate the participation and diagnostic yield of the parallel combination of questionnaire-based risk assessment (QRA) and FIT, FIT-only and QRA-only strategies in a CRC screening program in China.

Methods

The study included 29,626 individuals aged 40−74 years and invited to participate in a CRC screening program in China. Participants were first invited to undertake QRA and one-time FIT (OC-sensor). Participants with positive QRA or FIT were deemed to be high-risk individuals who were recommended for subsequent colonoscopy. Participation, detection rate, and resource demand for colonoscopy were calculated and compared.

Results

Of the 29,626 invitees, 20,203 completed the parallel combination, 8,592 completed the QRA-only, and 11 completed the FIT-only strategy. For the parallel combination, FIT-only, and QRA-only strategies, the overall positivity rates were 10.2% (2,928/28,806), 5.4% (1,096/20,214), and 6.8% (1,944/28,795), respectively; the yield of advanced neoplasm per 10,000 invitees were 46.9 [95% confidence interval (95% CI): 39.8−55.4], 36.8 (95% CI: 30.5−44.4), and 12.2 (95% CI: 8.8−16.8), respectively; the positive predictive values for detecting advanced neoplasms among participants who completed colonoscopy were 4.7% (95% CI: 4.0%−5.6%), 9.9% (95% CI: 8.3%−11.9%), and 1.9% (95% CI: 1.3%−2.6%), respectively; the number of colonoscopies required to detect one advanced neoplasm was 11.4 (95% CI: 9.8−13.4), 5.7 (95% CI: 4.8−6.7), and 28.4 (95% CI: 20.7−39.2), respectively.

Conclusions

The parallel combination of QRA and FIT did not show superior efficacy for detecting advanced neoplasm compared with FIT alone in this CRC screening program.

Optimizing Positivity Thresholds for a Risk-Adapted Screening Strategy in Colorectal Cancer Screening

INTRODUCTION

Risk-adapted screening combining the Asia-Pacific Colorectal Screening score, fecal immunochemical test (FIT), and colonoscopy improved the yield of colorectal cancer screening than FIT. However, the optimal positivity thresholds of risk scoring and FIT of such a strategy warrant further investigation.

METHODS

We included 3,407 participants aged 50-74 years undergoing colonoscopy from a colorectal cancer screening trial. For the risk-adapted screening strategy, subjects were referred for subsequent colonoscopy or FIT according to their risk scores. Diagnostic performance was evaluated for FIT and the risk-adapted screening method with various positivity thresholds. Furthermore, a modeled screening cohort was established to compare the yield and cost using colonoscopy, FIT, and the risk-adapted screening method in a single round of screening.

RESULTS

Risk-adapted screening method had higher sensitivity for advanced neoplasm (AN) (27.6%-76.3% vs 13.8%-17.3%) but lower specificity (46.6%-90.8% vs 97.4%-98.8%) than FIT did. In a modeled screening cohort, FIT-based screening would be slightly affected because the threshold varied with a reduction of 76.0%-80.9% in AN detection and 82.0%-84.4% in cost when compared with colonoscopy. By contrast, adjusting the threshold of Asia-Pacific Colorectal Screening score from 3 to 5 points for risk-adapted screening varied from an increase of 12.6%-14.1% to a decrease of 55.6%-60.1% in AN detection, with the reduction of cost from 4.2%-5.3% rising to 66.4%-68.5%.

DISCUSSION

With an appropriate positivity threshold tailored to clinical practice, the risk-adapted screening could save colonoscopy resources and cost compared with the colonoscopy-only and FIT-only strategies.

Comparison of multiple statistical models for the development of clinical prediction scores to detect advanced colorectal neoplasms in asymptomatic Thai patients

A good clinical prediction score can help in the risk stratification of patients with colorectal cancer (CRC) undergoing colonoscopy screening. The aim of our study was to compare model performance of binary logistic regression (BLR), polytomous logistic regression (PLR), and classification and regression tree (CART) between the clinical prediction scores of advanced colorectal neoplasia (ACN) in asymptomatic Thai patients.We conducted a cross-sectional study of 1311 asymptomatic Thai patients to develop a clinical prediction model. The possible predictive variables included sex, age, body mass index, family history of CRC in first-degree relatives, smoking, diabetes mellitus, and the fecal immunochemical test in the univariate analysis. Variables with a P value of .1 were included in the multivariable analysis, using the BLR, CART, and PLR models. Model performance, including the area under the receiver operator characteristic curve (AUROC), was compared between the model types.ACN was diagnosed in 53 patients (4.04%). The AUROCs were not significantly different between the BLR and CART models for ACN prediction with an AUROC of 0.774 (95% confidence interval [95% CI]: 0.706-0.842) and 0.765 (95% CI: 0.698-0.832), respectively (P = .712). A significant difference was observed between the PLR and CART models in predicting average to moderate ACN risk with an AUROC of 0.767 (95% CI: 0.695-0.839 vs AUROC 0.675 [95% CI: 0.599-0.751], respectively; P = .009).The BLR and CART models yielded similar accuracies for the prediction of ACN in Thai patients. The PLR model provided higher accuracy for ACN prediction than the CART model.

Assessing Individual Risk for High-Risk Early Colorectal Neoplasm for Pre-Selection of Screening in Shanghai, China: A Population-Based Nested Case-Control Study

Objective

To identify people with high-risk early colorectal neoplasm is highly desirable for pre-selection in colorectal cancer (CRC) screening in low-resource countries. We aim to build and validate a risk-based model so as to improve compliance and increase the benefits of screening.

Patients and Methods

Using data from the Shanghai CRC screening cohort, we conducted a population-based nested case–control study to build a risk-based model. Cases of early colorectal neoplasm were extracted as colorectal adenomas and stage 0-I CRC. Each case was matched with five individuals without neoplasm (controls) by the screening site and year of enrollment. Cases and controls were then randomly divided into two groups, with two thirds for building the risk prediction model and the other one third for model validation. Known risk factors were included for risk prediction models using logistic regressions. The area under the receiver operating characteristic curve (AUC) and Hosmer–Lemeshow chi-square statistics were used to evaluate model discrimination and calibration. The predicted individual risk probability was calculated under the risk regression equation.

Results

The model incorporating age, sex, family history and lifestyle factors including body mass index (BMI), smoking status, alcohol, regular moderate-to-intensity physical activity showed good calibration and discrimination. When the risk cutoff threshold was defined as 17%, the sensitivity and specificity of the model were 63.99% and 53.82%, respectively. The validation data analysis also showed well discrimination.

Conclusion

A risk prediction model combining personal and lifestyle factors was developed and validated for high-risk early colorectal neoplasm among the Chinese population. This risk-based model could improve the pre-selection for screening and contribute a lot to efficient population-based screening in low-resource countries.

Current Status of Colorectal Cancer and Its Public Health Burden in Thailand

Colorectal cancer (CRC) accounts for approximately 10.3% of new cancer cases in Thailand and is currently the 3rd most prevalent cancer found among the Thai population. Starting in 2017, the Thai government announced the national CRC screening program as a response to this important issue. Among the 70 million people currently residing in Thailand, 14 million require screening, while there are approximately a total of 1,000 endoscopists available to perform colonoscopy. Due to the limited resources and shortage of endoscopists in Thailand, applying a population-based one-step colonoscopy program as a primary screening method is not feasible. To reduce colonoscopy workload, with the help of others, including village health volunteers, institution-based health personnel, reimbursement coders, pathologists, and patients due for CRC screening, a two-step approach of one-time fecal immunochemical test (FIT), which prioritizes and filters out subjects for colonoscopy, is chosen. Moreover, additional adjustments to the optimal FIT cutoff value and the modified Asia-Pacific Colorectal Screening risk score, including body weight, were proposed to stratify the priority of colonoscopy schedule. This article aims to give an overview of the past and current policy developmental strategies and the current status of the Thailand CRC screening program.

PPV and Detection Rate of mt-sDNA Testing, FIT, and CT Colonography for Advanced Neoplasia: A Hierarchic Bayesian Meta-Analysis of the Noninvasive Colorectal Screening Tests

BACKGROUND. Noninvasive tests for colorectal cancer (CRC) screening and prevention limit the need for invasive colonoscopy to follow up positive test results. However, the relative performance characteristics of available noninvasive tests have not yet been adequately compared. OBJECTIVE. We performed a systematic review and meta-analysis to compare the diagnostic performance of the available noninvasive CRC screening tests, including multitarget stool DNA (mt-sDNA) testing, fecal immunochemical testing (FIT), and CT colonography (CTC), with an emphasis on comparison of PPV and detection rate (DR) for advanced neoplasia (AN; encompassing cases of advanced adenomas and CRC). EVIDENCE ACQUISITION. After systematic searches of MEDLINE and Google Scholar databases, 10 mt-sDNA, 27 CTC, and 88 FIT published screening studies involving 25,132, 33,493, and 2,355,958 asymptomatic adults, respectively, were included. Meta-analysis with hierarchic Bayesian modeling was conducted in accordance with Cochrane Collaboration and PRISMA guidelines to determine test positivity rates (TPRs) leading to optical colonoscopy, as well as PPVs and DRs for both AN and CRC. Different positivity thresholds were considered for FIT and CTC. EVIDENCE SYNTHESIS. Point estimates (with 95% credible intervals) from pooled Bayesian meta-analysis combining all thresholds for FIT and stratifying CTC results by a polyp size threshold of 6 mm or larger (CTC6) and 10 mm or larger (CTC10) were calculated. TPR was 13.5% (10.9-16.6%) for mt-sDNA testing, 6.4% (5.8-7.2%) for FIT, 13.4% (11.4-15.6%) for CTC6, and 6.6% (5.2-7.7%) for CTC10. AN PPV was 26.9% (95% credible interval, 21.8-33.2%) for mt-sDNA testing, 31.8% (29.3-34.5%) for FIT, 34.4% (27.2-41.0%) for CTC6, and 61.0% (54.0-70.0%) for CTC10. CRC PPV was 2.4% (1.5-3.9%) for mt-sDNA testing, 4.9% (4.3-5.3%) for FIT, 3.5% (2.5-4.8%) for CTC6, and 6.0% (4.3-8.0%) for CTC10. The DR for AN was 3.4% (95% credible interval, 2.5-4.8%) for mt-SDNA, 2.0% (1.8-2.3%) for FIT, 4.8% (4.0-6.5%) for CTC6, and 4.0% (3.0-4.6%) for CTC10. When FIT is restricted to a lower threshold (< 10 μg Hb/g feces), its performance profile is similar to that of mt-sDNA testing, although available data are limited. AN PPV odds ratios (relative to CTC10 as the reference) were 0.24 (95% credible interval, 0.17-0.33) for mt-sDNA testing, 0.30 (0.24-0.45) for FIT, and 0.33 (0.25-0.47) for CTC6. CONCLUSION. Among noninvasive CRC screening tests, CTC with a polyp size threshold of 10 mm or larger most effectively targets AN, preserving detection while also decreasing unnecessary colonoscopies compared with mt-sDNA testing and FIT. CLINICAL IMPACT. CTC performed with a polyp size threshold for colonoscopy referral set at 10 mm or larger represents the most effective and efficient noninvasive screening test for CRC prevention and detection.

Risk Stratification Score Improves Sensitivity for Advanced Colorectal Neoplasia in Colorectal Cancer Screening: The Oshima Study Workgroup

INTRODUCTION

Noninvasive colorectal cancer (CRC) screening methods with higher sensitivity for advanced colorectal neoplasia (ACN) than the fecal immunochemical test (FIT) alone are warranted. This study aimed to elucidate the diagnostic performance of a risk stratification score calculated using baseline individual characteristics and its combination with FIT for detecting ACN.

METHODS

This cross-sectional analysis of data from a prospective cohort in Izu Oshima, Japan, included asymptomatic individuals age 40-79 years who underwent both 2-day quantitative FIT and screening colonoscopy. The 8-point risk score, calculated based on age, sex, CRC family history, body mass index, and smoking history, was assessed. Colonoscopy results were used as reference.

RESULTS

Overall, 1,191 individuals were included, and 112 had ACN. The sensitivity and specificity of the 1-/2-day FIT (cutoff: 50-200 ng Hb/mL) for ACN were 17.9%-33.9% (4.9%-22.0% for right-sided ACN) and 91.8%-97.6%, respectively. The risk score's c-statistic for ACN was 0.66, and combining the score (cutoff: 5 points) with 1-/2-day FIT (cutoff: 50-200 ng Hb/mL) yielded a sensitivity and specificity for ACN of 46.4%-56.3% (43.9%-48.8% for right-sided ACN) and 76.6%-80.8%, respectively. The specificity of the risk score and FIT combination for all adenomatous lesions was 82.4%-86.4%.

DISCUSSION

The 8-point risk score remarkably increased the sensitivity for ACN, particularly for right-sided ACN. Although the specificity decreased, it was still maintained at a relatively high level. The risk score and FIT combination has the potential to become a viable noninvasive CRC screening option.

Gut microbiota dysbiosis signature is associated with the colorectal carcinogenesis sequence and improves the diagnosis of colorectal lesions

BACKGROUND AND AIM

The gut microbiota is associated with colorectal lesions in cases of precancer and colorectal cancer (CRC). However, there are apparent differences in studies on the gut microbiota in the pathogenic sequence from precancer to cancer. Here, we characterize the gut microbiota signatures of colorectal precancer and cancer and test their utility in detecting colorectal lesions in two independent Chinese cohorts.

METHODS

Stool samples collected from patients with precancer and CRC were subjected to 16S ribosomal RNA gene sequencing and metagenomic shotgun sequencing analyses, which revealed the microbial signatures of the two disease stages.

RESULTS

In comparison with healthy controls, lower microbial richness and diversity were observed in precancer and intensive interbacterial associations were found in CRC. We identified 41 bacteria that showed gradual increases while 12 bacteria showed gradual decreases at the genus level gradually during the development of CRC. Novel CRC-associated pathogenetic species were identified. Species units that contributed to altered microbial functions were identified in CRC patients and healthy controls. The microbial panel showed a comparable ability to fecal immunochemical test (FIT) in detecting CRC. However, the combination of microbes and FIT significantly improved the detection ability and sensitivity of colon lesions based on 18 genera. Microbial network analysis revealed a significant positive correlation among beneficial microbes and a negative correlation in detrimental phenotypes.

CONCLUSIONS

Microbial dysbiosis was revealed in colorectal lesions. The combination of microbial markers and FIT improved the CRC detection ability, which might assist in the early diagnosis of CRC.

Colorectal screening using the immunochemical faecal occult blood test kit among the Malaysian cohort participants

BACKGROUND

There has been a rapid increase in colorectal cancer (CRC) cases in Asian countries, including Malaysia. CRC is usually diagnosed at a late stage, and early detection of CRC is vital in improving survival. This study was conducted to determine the uptake rate of the immunochemical faecal occult blood test (iFOBT), the response rate to colonoscopy, and the CRC detection rate. We also wanted to identify the association between colorectal neoplasia and the Asia Pacific Colorectal Cancer Screening (APCS) scoring system.

METHODS

We recruited 2264 individuals from The Malaysian Cohort participants aged 35-65 years who consented to colorectal screening using the iFOBT kit from July 2017 until January 2019.

RESULTS

The response rate and positive iFOBT test rate of this study were 79.6% and 13.1% respectively. Among those with positive results, 125 individuals (52.7%) underwent colonoscopy; CRC was detected in six of them while 45 others (36.0%) had polyps. The overall CRC detection rate was 0.3% while the colorectal neoplasia detection rate (both colorectal cancer and colorectal polyps) was 2.3%. The APCS scoring indicated a significant association with colorectal neoplasia risk, with increasing trend by severity from moderate to high risk (3.46-11.14) compared to low risk. Most of the participants who were positive for iFOBT were those at high risk.

CONCLUSIONS

The awareness of CRC risk and iFOBT screening are important strategies for early detection of CRC. We showed a CRC detection rate of 0.3 % among those who volunteered to have the iFOBT screening.

Head-to-Head Comparison of the Performance of 17 Risk Models for Predicting Presence of Advanced Neoplasms in Colorectal Cancer Screening

OBJECTIVES

Many risk scores have been proposed to predict presence of advanced colorectal neoplasms, but a comprehensive comparison conducted in the same population is sparse. The aim of this study was to evaluate and directly compare the diagnostic performance of published risk prediction models for advanced colorectal neoplasms.

METHODS

Data were drawn from 2 cohorts of subjects undergoing screening colonoscopy in Germany, i.e., KolosSal (n = 16,195) and BliTz (n = 7,444). Absolute risks and relative risks were generated for the presence of at least 1 advanced neoplasm, taking the lowest risk group as the reference group. Performance of risk models was assessed by the area under the receiver operating characteristic curve (AUC) and compared by the net reclassification improvement.

RESULTS

The 2 cohorts included 1,917 (11.8%) and 848 (11.4%) participants with advanced neoplasm, respectively. Absolute risks were mostly between 5% and 10% among participants in the lowest risk group and between 15% and 20% among participants in the highest risk group, and relative risks mostly ranged from 2.0 to 4.0 across the risk models in both cohorts. The AUCs ranged from 0.58 to 0.65 in KolosSal and from 0.57 to 0.61 in BliTz for all risk scores. Compared to models with lower AUC, classification was significantly improved in most models with higher AUC.

DISCUSSION

Risk models for advanced colorectal neoplasms generally yielded modest discriminatory power, despite some variation in performance between models. Future studies should evaluate the performance of these risk models in racially diverse populations and investigate possible extensions, such as combination with polygenic risk scores.

Towards risk-stratified colorectal cancer screening. Adding risk factors to the fecal immunochemical test: Evidence, evolution and expectations

With increasing incidence and mortality, colorectal cancer (CRC) is a growing health problem worldwide. An effective way to address CRC is by screening for fecal (occult) blood by the fecal immunochemical test (FIT). However, there is room for improvement since precursor lesions and CRC bleed intermittent and can therefore be missed by the FIT (false negatives) or, the detected blood did not result from precursor lesions or CRC (false positives). This review provides the latest evidence on risk prediction models using FIT combined with additional risk factors before colonoscopy, which risk factors to include and if these models will better discriminate between normal findings and CRC compared to the FIT-only. Many prediction models are known for CRC, but compared to the FIT, these are less effective in detecting CRC. The literature search resulted in 645 titles where 11 papers matched the inclusion criteria and were analyzed. Comparing the FIT-only with the risk prediction models for detecting CRC resulted in a significantly increased discrimination for the models. In addition, 2 different risk-stratification categories before colonoscopy were distinguished, namely the 1-model approach which combined risk factors with FIT results in a prediction model while the 2 step approach used risk factors apart from the FIT. Finally, combining FIT with CRC risk factors by means of a model before colonoscopy seems effective regarding discriminative power, however, more research is needed for validation combined with transparent and standardized reporting to improve quality assessment, for which suggestions are reported in this study.

Performance Characteristics of Fecal Immunochemical Tests for Colorectal Cancer and Advanced Adenomatous Polyps: A Systematic Review and Meta-analysis

BACKGROUND

Studies report inconsistent performance of fecal immunochemical tests (FITs) for colorectal cancer (CRC) and advanced adenomas.

PURPOSE

To summarize performance characteristics of FITs for CRC and advanced adenomas in average-risk persons undergoing screening colonoscopy (reference standard) and to identify factors affecting these characteristics.

DATA SOURCES

Ovid MEDLINE, PubMed, Embase, and the Cochrane Library from inception through October 2018; reference lists of studies and reviews.

STUDY SELECTION

Two reviewers independently screened records to identify published English-language prospective or retrospective observational studies that evaluated FIT sensitivity and specificity for colonoscopic findings in asymptomatic, average-risk adults.

DATA EXTRACTION

Two authors independently extracted data and evaluated study quality.

DATA SYNTHESIS

Thirty-one studies (120 255 participants; 18 FITs) were included; all were judged to have low to moderate risk of bias. Performance characteristics depended on the threshold for a positive result. A threshold of 10 µg/g resulted in sensitivity of 0.91 (95% CI, 0.84 to 0.95) and a negative likelihood ratio of 0.10 (CI, 0.06 to 0.19) for CRC, whereas a threshold of greater than 20 µg/g resulted in specificity of 0.95 (CI, 0.94 to 0.96) and a positive likelihood ratio of 15.49 (CI, 9.82 to 22.39). For advanced adenomas, sensitivity was 0.40 (CI, 0.33 to 0.47) and the negative likelihood ratio was 0.67 (CI, 0.57 to 0.78) at 10 µg/g, and specificity was 0.95 (CI, 0.94 to 0.96) and the positive likelihood ratio was 5.86 (CI, 3.77 to 8.97) at greater than 20 µg/g. Studies had low to high heterogeneity, depending on the threshold. Although several FITs had adequate performance, sensitivity and specificity for CRC for 1 qualitative FIT were 0.90 and 0.91, respectively, at its single threshold of 10 µg/g; positive and negative likelihood ratios were 10.13 and 0.11, respectively. Comparison of 3 FITs at 3 thresholds was inconclusive: CIs overlapped, and the comparisons were across rather than within studies.

LIMITATIONS

Only English-language studies were included. Incomplete reporting limited quality assessment of some evidence. Performance characteristics are for 1-time rather than serial testing.

CONCLUSION

Single-application FITs have moderate to high sensitivity and specificity for CRC, depending on the positivity threshold. Sensitivity of 1-time testing for advanced adenomas is low, regardless of the threshold.

PRIMARY FUNDING SOURCE

Department of Medicine, Indiana University School of Medicine.

Overweight as an Additional Risk Factor for Colorectal Neoplasia in Lean Population

Background:

Overweight in Thailand is not as common as in Western countries. We sought to evaluate overweight as the additional risk factor that can increase the prediction of colorectal neoplasia (CRN) detection in Thais apart from the Asia-Pacific Colorectal Screening (APCS) score.

Methods:

We prospectively enrolled asymptomatic 338 subjects who underwent screening colonoscopy between November 2016 and September 2017. All risk factors according to APCS, BMI and the presence of metabolic syndrome were collected. Overweight was defined as BMI ≥23 kg/m². By APCS score, subjects were categorized into 1) high-risk and 2) average-risk. Using the combination of APCS score and overweight, subjects were stratified into 4 groups; high-risk with overweight (G1), average-risk with overweight (G2), high-risk with normal weight (G3) average-risk and with normal weight (G4). Logistic regression analysis was used to estimate the risk of detecting CRN.

Results:

The prevalence of CRN in the high-risk subjects was higher than that of in the average-risk subjects (49%vs.32%; OR, 2.00; 95%CI, 1.17-3.41). After adjustment for APCS risk factors and metabolic syndrome, overweight significantly increased the risk of detecting CRN (OR, 2.52; 95%CI, 1.57-4.05). Among the 4 groups, the detection rates of CRN were significantly different (G1=64%, G2=40%, G3=32% and G4=21%, p<0.01). The relative risk of detecting CRN increased when G1 (OR 6.49; 95%CI, 2.87-14.67), and G2 (2.42; 1.39-4.21) were compared with G4.

Conclusions:

In addition to the APCS score, overweight is an independent risk factor for detecting CRN. In Thai population, combining overweight and APCS score may be useful to improve the prediction for CRN.

Strategies for prevention of gastrointestinal cancers in developing countries: a systematic review

Background

Gastrointestinal cancers account for one third of total cancer incidence and mortality in developing countries. To date, there is no systematic synthesis of evidence regarding strategies to prevent gastrointestinal cancers in developing countries. We aimed to provide a systematic overview of studies evaluating strategies for prevention or early detection of the three most common gastrointestinal cancers (gastric, liver and colorectal cancer) in developing countries.

Methods

We searched MEDLINE, Web of Science and WHO Global Index Medicus databases for relevant articles published until October 2016 using combinations of the search terms “gastrointestinal”, “digestive system”, “gastric”, “liver”, “colorectal”, “cancer”, “prevention”, “early detection” and “developing country” (including names).

Results

Overall, 73 articles met the inclusion criteria, providing information on short– and long–term outcomes (up to 30 years) from various intervention studies (∼45% randomized). Trials on hepatitis B vaccination consistently showed vaccine efficacy over time and indicated long–term preventive effects on liver cancer incidence that start to become measurable at the population level. Studies on anti–H. pylori treatment suggested a reduction in gastric cancer incidence reaching statistical significance after long–term follow–up, while evidence regarding a preventive effect in persons with precancerous lesions is still inconclusive. The studies regarding colorectal cancer focused on early detection, ∼90% of which were restricted to intermediate endpoints.

Conclusion

In conclusion, there were a number of studies on gastric and liver cancer prevention in developing countries showing promising results after long–term follow–up. Important next steps include pooled meta–analyses as far as possible given the heterogeneity between studies as well as implementation research.

A combination of clinical risk stratification and fecal immunochemical test is useful for identifying persons with high priority of early colonoscopy

BACKGROUND

We aimed to develop a combination screening strategy for advanced colorectal neoplasia based on the Asia-Pacific Colorectal Screening score and fecal immunochemical test results.

METHODS

We reviewed the records of participants who had undergone a colonoscopy and fecal immunochemical test as part of a comprehensive health screening program. The prevalence of advanced colorectal neoplasia in participants 40-49 years old was analyzed according to Asia-Pacific Colorectal Screening scores and fecal immunochemical test results.

RESULTS

We analyzed the data of 9205 participants 40-49 years old and 3215 participants ≥50 years old. The prevalence of advanced colorectal neoplasia in participants 40-49 years old was 1.0%, 2.1%, 7.1%, and 13.4% in the "fecal immunochemical test (-) & Asia-Pacific Colorectal Screening<2," "fecal immunochemical test (-) & Asia-Pacific Colorectal Screening≥2," "fecal immunochemical test (+) & Asia-Pacific Colorectal Screening<2," and "fecal immunochemical test (+) & Asia-Pacific Colorectal Screening≥2" subgroups, respectively. The prevalence of advanced colorectal neoplasia in "fecal immunochemical test (+) & Asia-Pacific Colorectal Screening≥2" subgroup was higher than in participants ≥50 years old with Asia-Pacific Colorectal Screening≥4 (13.4% vs. 5.8%, P<0.001).

CONCLUSIONS

Fecal immunochemical test-positive individuals 40-49 years old with an Asia-Pacific Colorectal Screening≥2 have a higher risk of advanced colorectal neoplasia than individuals ≥50 years old with an Asia-Pacific Colorectal Screening≥4.

Risk-adjusted colorectal cancer screening using the FIT and routine screening data: development of a risk prediction model

Background:

The faecal immunochemical test (FIT) is replacing the guaiac faecal occult blood test in colorectal cancer screening. Increased uptake and FIT positivity will challenge colonoscopy services. We developed a risk prediction model combining routine screening data with FIT concentration to improve the accuracy of screening referrals.

Methods:

Multivariate analysis used complete cases of those with a positive FIT (⩾20 μg g⁻¹) and diagnostic outcome (n=1810; 549 cancers and advanced adenomas). Logistic regression was used to develop a risk prediction model using the FIT result and screening data: age, sex and previous screening history. The model was developed further using a feedforward neural network. Model performance was assessed by discrimination and calibration, and test accuracy was investigated using clinical sensitivity, specificity and receiver operating characteristic curves.

Results:

Discrimination improved from 0.628 with just FIT to 0.659 with the risk-adjusted model (P=0.01). Calibration using the Hosmer–Lemeshow test was 0.90 for the risk-adjusted model. The sensitivity improved from 30.78% to 33.15% at similar specificity (FIT threshold of 160 μg g⁻¹). The neural network further improved model performance and test accuracy.

Conclusions:

Combining routinely available risk predictors with the FIT improves the clinical sensitivity of the FIT with an increase in the diagnostic yield of high-risk adenomas.

Impact of Fecal Hb Levels on Advanced Neoplasia Detection and the Diagnostic Miss Rate For Colorectal Cancer Screening in High-Risk vs. Average-Risk Subjects: a Multi-Center Study

Objectives:

The Asia-Pacific Colorectal Screening (APCS) scoring system was developed to identify high-risk subjects for advanced neoplasia. However, the appropriate fecal immunochemical test (FIT) cutoff for high-risk population may be different from that of average-risk population. We aimed to evaluate the FIT performance at different cutoffs in high-risk subjects undergoing colorectal cancer (CRC) screening.

Methods:

We prospectively enrolled asymptomatic subjects aged 50–75 years. Using the APCS score, subjects were stratified into either the average-risk or high-risk groups. All subjects were tested with one-time quantitative FIT and underwent colonoscopy. We compared the FIT performance for advanced neoplasia between two groups using different cutoffs (5 (FIT5), 10 (FIT10), 20 (FIT20), 30 (FIT30), and 40 (FIT40) μg Hb/g feces).

Results:

Overall, 1,713 subjects were recruited, and 1,222 (71.3%) and 491 (28.7%) were classified as average-risk and high-risk, respectively. Advanced neoplasia was detected in 90 (7.4%) of the average-risk subjects and 65 (13.2%) of the high-risk subjects. In the high-risk group, by decreasing the cutoff from FIT40 to FIT5, the sensitivity increased by 33.8 percentage points with decreased specificity by 11 percentage points. In the average-risk group, the sensitivity increased by 20 percentage points with decreased specificity by 9.6 percentage points. At the lowest cutoff (FIT5), the number of needed colonoscopies to find one advanced neoplasia was 2.8 and 6.1 for the high-risk and average-risk groups, respectively.

Conclusions:

Using an appropriate FIT cutoff for CRC screening in high-risk subjects could improve CRC screening performance and reduce the unnecessary colonoscopies. To maintain high sensitivity and specificity for advanced neoplasia, the optimal cutoff FIT in the high-risk subjects should be lower than that in the average-risk subjects.

Identifying the optimal strategy for screening of advanced colorectal neoplasia

BACKGROUND AND AIM

To guide selection of optimal screening strategies for advanced colorectal neoplasia (ACRN), we evaluated the screening performances of sigmoidoscopy, fecal immunochemical test (FIT), and the Asia-Pacific Colorectal Screening (APCS) system, as well as combinations of these techniques.

METHODS

We reviewed the records of participants who had undergone a colonoscopy and FIT as part of a comprehensive health-screening program. Results of sigmoidoscopy were estimated from lesions under colonoscopic examination. The screening strategies were classified as sigmoidoscopy-based, FIT-based, and APCS-based. The sensitivity and reduction of number needed to colonoscope (NNScope) of each screening strategy were assessed.

RESULTS

Of 23 023 participants, 398 (1.7%) had ACRN. To predict the presence of ACRN, sigmoidoscopy was the most effective method (odds ratio [OR]: 22.96, 95% confidence interval [CI]: 18.26-29.07), followed by FIT (OR: 7.18, 95% CI: 5.28-9.68) and APCS (high risk [≥4] OR: 2.59, 95% CI: 1.87-3.58; moderate risk [2-3] OR: 1.66, 95% CI: 1.28-2.17). Regarding sigmoidoscopy-based strategies, "sigmoidoscopy positive alone" and "sigmoidoscopy positive or APCS ≥4" were optimal strategies (reduction of NNScope: 79-86%; sensitivity: 73-78%). In the case of FIT-based strategies, "FIT positive or APCS ≥4" was the optimal strategy (reduction of NNScope: 72%; sensitivity: 37%). With regard to the APCS system only, "APCS ≥2" and "APCS ≥4" were recommended as sensitivity-preferred and reduction in NNScope-preferred strategies, respectively.

CONCLUSIONS

The performance in ACRN prediction differs among screening methods (sigmoidoscopy, FIT, and APCS). Among the various single or combined screening strategies, several specific strategies can be chosen depending on medical resources, financial budgets, and screenee preference.

A New Scoring System to Predict the Risk for High-risk Adenoma and Comparison of Existing Risk Calculators

BACKGROUND

Colorectal cancer (CRC) screening guidelines likely over-generalizes CRC risk, 35% of Americans are not up to date with screening, and there is growing incidence of CRC in younger patients.

GOALS

We developed a practical prediction model for high-risk colon adenomas in an average-risk population, including an expanded definition of high-risk polyps (≥3 nonadvanced adenomas), exposing higher than average-risk patients. We also compared results with previously created calculators.

STUDY

Patients aged 40 to 59 years, undergoing first-time average-risk screening or diagnostic colonoscopies were evaluated. Risk calculators for advanced adenomas and high-risk adenomas were created based on age, body mass index, sex, race, and smoking history. Previously established calculators with similar risk factors were selected for comparison of concordance statistic (c-statistic) and external validation.

RESULTS

A total of 5063 patients were included. Advanced adenomas, and high-risk adenomas were seen in 5.7% and 7.4% of the patient population, respectively. The c-statistic for our calculator was 0.639 for the prediction of advanced adenomas, and 0.650 for high-risk adenomas. When applied to our population, all previous models had lower c-statistic results although one performed similarly.

CONCLUSIONS

Our model compares favorably to previously established prediction models. Age and body mass index were used as continuous variables, likely improving the c-statistic. It also reports absolute predictive probabilities of advanced and high-risk polyps, allowing for more individualized risk assessment of CRC.

The Optimal Cut-Off Level of The Fecal Immunochemical Test For Colorectal Cancer Screening in a Country with Limited Colonoscopy Resources: A Multi-Center Study from Thailand

Background:

Selecting the cut-off point for the fecal immunochemical test (FIT) for colorectal cancer (CRC) screening programs is of prime importance. The balance between the test performance for detecting advanced neoplasia and the available colonoscopy resources should be considered. We aimed to identify the optimal cut-off of FIT for advanced neoplasia in order to minimize colonoscopy burden.

Methods:

We conducted a multi-center study in 6 hospitals from diverse regions of Thailand. Asymptomatic participants, aged 50-75 years, were tested with one-time quantitative FIT (OC-SENSOR, Eiken Chemical Co.,Ltd., Tokyo, Japan) and all participants underwent colonoscopy. We assessed test performance in detecting advanced neoplasia (advanced adenoma and CRC) and measured the burden of colonoscopy with different cut-offs [25 (FIT25), 50 (FIT50), 100 (FIT100), 150 (FIT150), and 200 (FIT200)ng/ml].

Results:

Among 1,479 participants, advanced neoplasia and CRC were found in 137 (9.3%) and 14 (0.9%), respectively. From FIT25 to FIT200, the positivity rate decreased from 18% to 4.9%. For advanced neoplasia, an increased cut-off decreased sensitivity from 42.3% to 16.8% but increased specificity from 84.2% to 96.3%. The increased cut-off increased the positive predictive value (PPV) from 21.5% to 31.5%. However, all cut-off points provided a high negative predictive value (NPV) (>90%). For CRC, the miss rate for FIT25 to FIT 150 was the same (n=3, 21%), whereas that with FIT200 increased to 35% (n=5).

Conclusions:

In a country with limited-colonoscopy resources, using FIT150 may be preferred because it offers both high PPV and NPV for advanced neoplasia detection. It could also decrease colonoscopy workload, while maintaining a CRC miss rate similar to those with lower cut-offs.

High prevalence of advanced colorectal neoplasia in the Thai population: a prospective screening colonoscopy of 1,404 cases

Background

Increasing morbidity and mortality from colorectal cancer is evident in recent years in the developing Asian nations. Particularly in Thailand and most neighbouring low-income countries, screening colonoscopy is not yet recommended nor implemented at the national policy level.

Methods

Screening colonoscopy was offered to 1,500 healthy volunteers aged 50–65 years old who were registered into the program between July 2009 and June 2010. Biopsy and surgery was performed depending on the identified lesions. Fecal immunochemical tests (FIT) were additionally performed for comparison with colonoscopy.

Results

There were 1,404 participants who underwent colonoscopy. The mean age of the cohort was 56.9 ± 4.2 years and 69.4 % were females. About 30 % (411 cases) of all colonoscopies had abnormal colonoscopic findings, and of these, 256 cases had adenomatous polyps. High risk adenomas (villous or tubulovillous or high grade dysplasia or size > 1 cm or > 3 adenomatous polyps) were found in 98 cases (7 %), low risk adenoma in 158 cases (11.3 %), and hyperplastic polyps in 119 cases (8.5 %). Eighteen cases (1.3 %) had colorectal cancer and 90 % of them (16 cases) were non-metastatic including five stage 0 cases, seven stage I cases, and four stage IIA cases. Only two cases had metastasis: one to regional lymph nodes (stage IIIB) and another to other organs (stage IVA). The most common cancer site was the distal intestine including rectum (7 cases, 38.9 %) and sigmoid colon (7 cases, 38.9 %). Ten colorectal cancer cases had positive FIT whereas 8 colorectal cancer cases were FIT-negative. The sensitivity and specificity of FIT was 55.6 % and 96.2 %, respectively, while the positive predictive value was 16.4 % and negative predictive value was 99.4 %. The overall survival of colorectal cancer cases at 5-year was 83.3 %.

Conclusion

High prevalence of colorectal cancer and high-risk adenoma was found in the Thai population aged 50–65 years old by screening colonoscopy. FIT was not sensitive enough to detect colorectal cancer in this asymptomatic cohort. Integration of screening colonoscopy into the national cancer screening program should be implemented to detect early cases of advanced colorectal neoplasia and improve survival of colorectal cancer patients in Thailand.

Faecal haemoglobin concentration is related to detection of advanced colorectal neoplasia in the next screening round

Objective

To examine associations between faecal haemoglobin concentrations below the cut-off used in colorectal cancer screening and outcomes in the next screening round.

Methods

In the Scottish Bowel Screening Programme, faecal haemoglobin concentrations and diagnostic outcomes were investigated for participants with a negative result (faecal haemoglobin concentrations < 80.0 µg Hb/g faeces), followed by a positive result within two years.

Results

Of 37,780 participants with negative results, at the next screening round, 556 (1.5%) screened positive and 30,293 (80.2%) negative. Initial median faecal haemoglobin concentrations (2.1 µg Hb/g faeces, IQR: 0.0–13.2) were higher in those with subsequent positive results than those with subsequent negative results (0.0 µg Hb/g faeces, IQR: 0.0–1.4; p < 0.0001). Using faecal haemoglobin concentrations 0.0–19.9 µg Hb/g faeces as reference, logistic regression analysis showed high adjusted odds ratios for advanced neoplasia (advanced neoplasia: colorectal cancer or higher risk adenoma) detection at the next round of 14.3 (95% CI: 8.9–23.1) in those with initial faecal haemoglobin concentrations 20.0–39.9 µg Hb/g faeces, and 38.0 (95% CI: 20.2–71.2) with 60.0–79.9 µg Hb/g faeces.

Conclusions

A higher proportion of participants with faecal haemoglobin concentrations of ≥ 20 µg Hb/g faeces had advanced neoplasia detected at the next round than participants with lower faecal haemoglobin concentrations. Although most relevant when using high faecal haemoglobin concentrations cut-offs, studies of faecal haemoglobin concentrations and outcomes over screening rounds may provide strategies to direct available colonoscopy towards those at highest risk.

Adding family history to faecal immunochemical testing increases the detection of advanced neoplasia in a colorectal cancer screening programme

BACKGROUND

Faecal immunochemical testing (FIT) for colorectal cancer (CRC) screening has suboptimal sensitivity for detecting advanced neoplasia. To increase its performance, FIT could be combined with other risk factors.

AIM

To evaluate the incremental yield of a screening programme using a positive FIT or a CRC family history, to offer a diagnostic colonoscopy.

METHODS

For this post hoc analysis, data were collected in the colonoscopy arm of a colonoscopy or colonography for screening study. In this study, 6600 randomly selected, asymptomatic men and women (50-75 years) were invited for screening colonoscopy. 1112 Participants completed a FIT and a questionnaire prior to colonoscopy. We compared the yield of FIT-only and FIT combined with CRC family history, defined as having one or more first-degree relatives with CRC.

RESULTS

At a 10 μg Hb/g faeces FIT-positivity threshold the combined strategy would increase the yield from 36 (3.2%; CI: 2.4-4.5%) to 53 (4.8%; CI: 3.7-6.2%) cases of advanced neoplasia, at the expense of 148 additional negative colonoscopies. Sensitivity in detecting advanced neoplasia would increase from 36% (CI: 26-46%) to 52% (CI: 42-63%), whereas specificity would decrease from 93% (CI: 92-95%) to 79% (CI: 76-81%). The strategy will be preferred if one accepts 8.8 false positives for every additional participant in whom advanced neoplasia can be detected.

CONCLUSIONS

Offering colonoscopy to those with a positive FIT or CRC family history increases the yield of a FIT-based screening programme. Depending on the number of negative colonoscopies one accepts, this combined approach can be considered for improving CRC screening.

FIT for the future: a case for risk-based colorectal cancer screening using the faecal immunochemical test

Worldwide, the guaiac faecal occult blood test (gFOBT) is being replaced with the more accurate faecal immunochemical test (FIT) for colorectal cancer (CRC) screening. From January 2016, the National Screening Committee in the UK has recommended a change from the gFOBT to the FIT following a successful Bowel Cancer Screening Programme pilot study with over 40 000 participants. Although the test has shown improved uptake and the ability to detect significantly more colorectal cancers and advanced adenomas, the higher uptake and test positivity will challenge the capacity of colonoscopy services. One of the main advantages of the FIT is that it provides a quantitative haemoglobin concentration which has been shown to relate to the risk of CRC. Risk scoring systems which combine the FIT concentration with risk factor assessment have been shown to improve the sensitivity of the test. This individualized approach to screening could enable those at greatest risk to be referred for colonoscopy, optimizing resource use and ultimately patient outcomes.

The Secondary Quality Indicator to Improve Prediction of Adenoma Miss Rate Apart from Adenoma Detection Rate

OBJECTIVES

Adenoma detection rate (ADR) cannot distinguish between endoscopists who detect one adenoma and those who detect ≥2 adenomas. Hypothetically, adenoma miss rate (AMR) may be significant for endoscopists with high ADRs who examine the rest of colon with less care after detecting first polyp. Our objective was to evaluate other quality indicators plus ADR vs. ADR alone in prediction of AMR.

METHODS

We conducted a cross-sectional study of asymptomatic participants aged 50-75 years who underwent back-to-back screening colonoscopies by four faculty endoscopists. Each round of colonoscopy was performed by two of the endoscopists in a randomized order. During each round of colonoscopy, all detected polyps were removed. The second endoscopist was blinded to the results of the first. The total number of adenomas per positive participant (APP), the total number of adenomas per colonoscopy (APC), the additional adenomas found after the first adenoma per colonoscopy (ADR-Plus), and ADR were calculated for prediction of AMR.

RESULTS

In all, 200 participants underwent back-to-back colonoscopies. There were no significant differences in ADRs of four endoscopists (44, 50, 54, and 46%). APPs were 1.91, 2.12, 2.19, and 2.43. APCs were 0.84, 1.06, 1.18, and 1.12. ADR-Plus were 0.40, 0.56, 0.64, and 0.66, respectively. AMRs differed significantly between the endoscopists (36, 27, 21, and 13%; P=0.01). There was no correlation between ADR and AMR (r=-0.25; P=0.75). Whereas APP exhibited a strong inverse correlation with AMRs (r=-0.99; P<0.01). APC and ADR-Plus appeared to be inversely correlated with AMR, however this was not statistically significant (r=-0.82; P=0.18 and r=-0.93; P=0.07, respectively).

CONCLUSIONS

Among high-ADR endoscopists, AMRs still varied. APP may be a promising secondary indicator for distinguishing between the one-and-done polyp endoscopist and the meticulous endoscopist. The evaluation of influence of new metrics on colorectal cancer (CRC) prevention requires a larger population-based study.

Colorectal cancer screening of the general population in East Asia

In recent years, the incidence of colorectal cancer (CRC) has been increasing, and CRC has been becoming the major cause of cancer deaths in Asian countries. Therefore, an organized screening program to reduce CRC incidence and mortality is currently implemented in each country. In the present review, we summarize the current status and future perspectives of CRC screening of the general population in East Asian and South-East Asian countries. The fecal occult blood test is widely used for CRC screening in these countries, and its effectiveness in reducing CRC incidence and mortality has been demonstrated; however, the low participation rate in CRC screening programs is a problem to be solved in every country. Improvement in the public awareness of CRC and promotion of CRC screening by physicians will help to raise the participation rate and reduce the number of deaths caused by CRC. Regarding screening colonoscopy, several studies have recently demonstrated its effectiveness in reducing CRC incidence and mortality. However, at present, CRC screening colonoscopy is not adopted as a primary population-based screening tool because of staffing constraints in relation to large population sizes, increased medical costs, and potential adverse events (e.g., perforation and drug-induced anaphylaxis). Further study is required to consider colonoscopy as CRC screening that is established in Western countries.