Does a negative screening colonoscopy ever need to be repeated?

Automated curation of large-scale cancer histopathology image datasets using deep learning

BACKGROUND

Artificial intelligence (AI) has numerous applications in pathology, supporting diagnosis and prognostication in cancer. However, most AI models are trained on highly selected data, typically one tissue slide per patient. In reality, especially for large surgical resection specimens, dozens of slides can be available for each patient. Manually sorting and labelling whole-slide images (WSIs) is a very time-consuming process, hindering the direct application of AI on the collected tissue samples from large cohorts. In this study we addressed this issue by developing a deep-learning (DL)-based method for automatic curation of large pathology datasets with several slides per patient.

METHODS

We collected multiple large multicentric datasets of colorectal cancer histopathological slides from the United Kingdom (FOXTROT, N = 21,384 slides; CR07, N = 7985 slides) and Germany (DACHS, N = 3606 slides). These datasets contained multiple types of tissue slides, including bowel resection specimens, endoscopic biopsies, lymph node resections, immunohistochemistry-stained slides, and tissue microarrays. We developed, trained, and tested a deep convolutional neural network model to predict the type of slide from the slide overview (thumbnail) image. The primary statistical endpoint was the macro-averaged area under the receiver operating curve (AUROCs) for detection of the type of slide.

RESULTS

In the primary dataset (FOXTROT), with an AUROC of 0.995 [95% confidence interval [CI]: 0.994-0.996] the algorithm achieved a high classification performance and was able to accurately predict the type of slide from the thumbnail image alone. In the two external test cohorts (CR07, DACHS) AUROCs of 0.982 [95% CI: 0.979-0.985] and 0.875 [95% CI: 0.864-0.887] were observed, which indicates the generalizability of the trained model on unseen datasets. With a confidence threshold of 0.95, the model reached an accuracy of 94.6% (7331 classified cases) in CR07 and 85.1% (2752 classified cases) for the DACHS cohort.

CONCLUSION

Our findings show that using the low-resolution thumbnail image is sufficient to accurately classify the type of slide in digital pathology. This can support researchers to make the vast resource of existing pathology archives accessible to modern AI models with only minimal manual annotations.

Deep learning for dual detection of microsatellite instability and POLE mutations in colorectal cancer histopathology

In the spectrum of colorectal tumors, microsatellite-stable (MSS) tumors with DNA polymerase ε (POLE) mutations exhibit a hypermutated profile, holding the potential to respond to immunotherapy similarly to their microsatellite-instable (MSI) counterparts. Yet, due to their rarity and the associated testing costs, systematic screening for these mutations is not commonly pursued. Notably, the histopathological phenotype resulting from POLE mutations is theorized to resemble that of MSI. This resemblance not only could facilitate their detection by a transformer-based Deep Learning (DL) system trained on MSI pathology slides, but also indicates the possibility for MSS patients with POLE mutations to access enhanced treatment options, which might otherwise be overlooked. To harness this potential, we trained a Deep Learning classifier on a large dataset with the ground truth for microsatellite status and subsequently validated its capabilities for MSI and POLE detection across three external cohorts. Our model accurately identified MSI status in both the internal and external resection cohorts using pathology images alone. Notably, with a classification threshold of 0.5, over 75% of POLE driver mutant patients in the external resection cohorts were flagged as "positive" by a DL system trained on MSI status. In a clinical setting, deploying this DL model as a preliminary screening tool could facilitate the efficient identification of clinically relevant MSI and POLE mutations in colorectal tumors, in one go.

Encrypted federated learning for secure decentralized collaboration in cancer image analysis

Artificial intelligence (AI) has a multitude of applications in cancer research and oncology. However, the training of AI systems is impeded by the limited availability of large datasets due to data protection requirements and other regulatory obstacles. Federated and swarm learning represent possible solutions to this problem by collaboratively training AI models while avoiding data transfer. However, in these decentralized methods, weight updates are still transferred to the aggregation server for merging the models. This leaves the possibility for a breach of data privacy, for example by model inversion or membership inference attacks by untrusted servers. Somewhat-homomorphically-encrypted federated learning (SHEFL) is a solution to this problem because only encrypted weights are transferred, and model updates are performed in the encrypted space. Here, we demonstrate the first successful implementation of SHEFL in a range of clinically relevant tasks in cancer image analysis on multicentric datasets in radiology and histopathology. We show that SHEFL enables the training of AI models which outperform locally trained models and perform on par with models which are centrally trained. In the future, SHEFL can enable multiple institutions to co-train AI models without forsaking data governance and without ever transmitting any decryptable data to untrusted servers.

Interval post-colonoscopy colorectal cancer following a negative colonoscopy in a fecal immunochemical test-based screening program

BACKGROUND

 In the Dutch colorectal (CRC) screening program, fecal immunochemical test (FIT)-positive individuals are referred for colonoscopy. If no relevant findings are detected at colonoscopy, individuals are reinvited for FIT screening after 10 years. We aimed to assess CRC risk after a negative colonoscopy in FIT-positive individuals.

METHODS

 In this cross-sectional cohort study, data were extracted from the Dutch national screening information system. Participants with a positive FIT followed by a negative colonoscopy between 2014 and 2018 were included. A negative colonoscopy was defined as a colonoscopy during which no more than one nonvillous, nonproximal adenoma < 10 mm or serrated polyp < 10 mm was found. The main outcome was interval post-colonoscopy CRC (iPCCRC) risk. iPCCRC risk was reviewed against the risk of interval CRC after a negative FIT (FIT IC) with a 2-year screening interval.

RESULTS

 35 052 FIT-positive participants had a negative colonoscopy and 24 iPCCRCs were diagnosed, resulting in an iPCCRC risk of 6.85 (95 %CI 4.60-10.19) per 10 000 individuals after a median follow-up of 1.4 years. After 2.5 years of follow-up, age-adjusted iPCCRC risk was approximately equal to FIT IC risk at 2 years.

CONCLUSION

 Risk of iPCCRC within a FIT-based CRC screening program was low during the first years after colonos-copy but, after 2.5 years, was the same as the risk in FIT-negative individuals at 2 years, when they are reinvited for screening. Colonoscopy quality may therefore require further improvement and FIT screening interval may need to be reduced after negative colonoscopy.

Methods and biomarkers for early detection, prediction, and diagnosis of colorectal cancer

Colorectal cancer (CRC) is one of the most common digestive diseases worldwide. It has steadily ascended to the top three cancers in terms of incidence and mortality. The primary cause is the inability to diagnose it at an early stage. Therefore, early detection and diagnosis are essential for colorectal cancer prevention. Although there are now various methods for CRC early detection, in addition to recent developments in surgical and multimodal therapy, the poor prognosis and late detection of CRC still remain significant. Thus, it is important to investigate novel technologies and biomarkers to improve the sensitization and specification of CRC diagnosis. Here, we present some common methods and biomarkers for early detection and diagnosis of CRC, we hope this review will encourage the adoption of screening programs and the clinical use of these potential molecules as biomarkers for CRC early detection and prognosis.

Generalizable biomarker prediction from cancer pathology slides with self-supervised deep learning: A retrospective multi-centric study

Deep learning (DL) can predict microsatellite instability (MSI) from routine histopathology slides of colorectal cancer (CRC). However, it is unclear whether DL can also predict other biomarkers with high performance and whether DL predictions generalize to external patient populations. Here, we acquire CRC tissue samples from two large multi-centric studies. We systematically compare six different state-of-the-art DL architectures to predict biomarkers from pathology slides, including MSI and mutations in BRAF, KRAS, NRAS, and PIK3CA. Using a large external validation cohort to provide a realistic evaluation setting, we show that models using self-supervised, attention-based multiple-instance learning consistently outperform previous approaches while offering explainable visualizations of the indicative regions and morphologies. While the prediction of MSI and BRAF mutations reaches a clinical-grade performance, mutation prediction of PIK3CA, KRAS, and NRAS was clinically insufficient.

Impact of Expanding Screening Colonoscopy Interval on Providers Choice of Prescribing Colonoscopy for Colorectal Cancer Screening

GOALS

We investigated if increasing the colonoscopy screening interval from 10 to 15 years would increase provider preferences for colonoscopy as a screening test. We further examined whether having colonoscopy performed at a 15-year interval by an endoscopist with a high adenoma detection rate would influence preferences.

BACKGROUND

Colonoscopy is recommended every 10 years in average risk individuals without polyps for colorectal cancer (CRC) screening. The use of a 15-year interval offers substantial protection, increases cost-effectiveness, and might make colonoscopy more attractive to patients and health care providers who order CRC screening tests.

STUDY

An anonymous online survey of health care providers across a health care system that serves a single US state and encompasses both academic and community physicians was conducted. Physicians and nurse practitioners in family medicine, obstetrics-gynecology, and internal medicine were included. Providers were asked to indicate their preference for CRC screening tests as a proportion of tests they prescribe among 5 common screening tools. Responses were compared for current colonoscopy screening intervals and if the screening intervals are increased to 15 years.

RESULTS

One hundred and twelve (34%) responded of 326 providers. Colonoscopy was the most frequently ordered test for CRC screening. Increasing screening interval from 10 to 15 years increased the choice of colonoscopy from 75.2% to 78.6% ( P =0.003).

CONCLUSIONS

Expanding colonoscopy screening interval to 15 years could produce an increase in physicians and nurse practitioners choice of using colonoscopy for CRC screening, but the clinical impact appears minor. Additional surveys of patients and providers are needed.

Swarm learning for decentralized artificial intelligence in cancer histopathology

Artificial intelligence (AI) can predict the presence of molecular alterations directly from routine histopathology slides. However, training robust AI systems requires large datasets for which data collection faces practical, ethical and legal obstacles. These obstacles could be overcome with swarm learning (SL), in which partners jointly train AI models while avoiding data transfer and monopolistic data governance. Here, we demonstrate the successful use of SL in large, multicentric datasets of gigapixel histopathology images from over 5,000 patients. We show that AI models trained using SL can predict BRAF mutational status and microsatellite instability directly from hematoxylin and eosin (H&E)-stained pathology slides of colorectal cancer. We trained AI models on three patient cohorts from Northern Ireland, Germany and the United States, and validated the prediction performance in two independent datasets from the United Kingdom. Our data show that SL-trained AI models outperform most locally trained models, and perform on par with models that are trained on the merged datasets. In addition, we show that SL-based AI models are data efficient. In the future, SL can be used to train distributed AI models for any histopathology image analysis task, eliminating the need for data transfer.

A decentralized, privacy-preserving machine learning framework used to train a clinically relevant AI system identifies actionable molecular alterations in patients with colorectal cancer by use of routine histopathology slides collected in real-world settings.

Weakly supervised end-to-end artificial intelligence in gastrointestinal endoscopy

Artificial intelligence (AI) is widely used to analyze gastrointestinal (GI) endoscopy image data. AI has led to several clinically approved algorithms for polyp detection, but application of AI beyond this specific task is limited by the high cost of manual annotations. Here, we show that a weakly supervised AI can be trained on data from a clinical routine database to learn visual patterns of GI diseases without any manual labeling or annotation. We trained a deep neural network on a dataset of N = 29,506 gastroscopy and N = 18,942 colonoscopy examinations from a large endoscopy unit serving patients in Germany, the Netherlands and Belgium, using only routine diagnosis data for the 42 most common diseases. Despite a high data heterogeneity, the AI system reached a high performance for diagnosis of multiple diseases, including inflammatory, degenerative, infectious and neoplastic diseases. Specifically, a cross-validated area under the receiver operating curve (AUROC) of above 0.70 was reached for 13 diseases, and an AUROC of above 0.80 was reached for two diseases in the primary data set. In an external validation set including six disease categories, the AI system was able to significantly predict the presence of diverticulosis, candidiasis, colon and rectal cancer with AUROCs above 0.76. Reverse engineering the predictions demonstrated that plausible patterns were learned on the level of images and within images and potential confounders were identified. In summary, our study demonstrates the potential of weakly supervised AI to generate high-performing classifiers and identify clinically relevant visual patterns based on non-annotated routine image data in GI endoscopy and potentially other clinical imaging modalities.

Yield of a second right colon examination during colonoscopy after a first examination using a mucosal exposure device

BACKGROUND AND AIMS

Double right colon examination during colonoscopy has been advocated to reduce the risk of interval cancer in the right colon. Whether 2 examinations are necessary when the first examination is performed with a mucosal exposure device is uncertain. We documented the rates of missed adenomas, sessile serrated lesions, and hyperplastic polyps after an initial right colon examination by a high-level detector using a mucosal exposure device.

METHODS

At a single tertiary hospital outpatient practice, we prospectively collected data on the yield of a second examination of the right colon after an initial examination by a single high-detecting colonoscopist using a mucosal exposure device.

RESULTS

During the study period, 1331 eligible consecutive patients underwent colonoscopy. Right colon adenoma, sessile serrated lesion, and hyperplastic polyp miss rates were 15.8%, 14.1%, and 16.7%, respectively. Four percent of patients had adenomas detected in the right colon only with a second examination.

CONCLUSIONS

A second examination of the right colon is warranted, even when using a distal mucosal exposure device to perform colonoscopy.

Hazard function analysis for development of second primary colorectal cancer after surgery for primary colorectal cancer

BACKGROUND AND AIM

Although history of colorectal cancer (CRC) is a known risk factor for developing second CRC, the optimal surveillance protocol has not been established. Using hazard function analysis to evaluate changes in the hazard rate for the development of second primary CRCs or high-grade adenomas (HGAs), we aimed to clarify when and on whom to focus in order to effectively identify second primary colorectal neoplasms after initial surgery for CRC.

METHODS

We retrospectively enrolled 1823 consecutive patients with stage 0-III CRCs who underwent radical surgery between 2004 and 2015, and subsequent colonoscopic surveillance after surgery. The time-course changes in the risk rates for developing metachronous CRC and HGA after surgery were assessed.

RESULTS

A peak was observed at 1.22 years after surgery in the hazard function curve for secondary colorectal neoplasms, which decreased until 4 years, then plateaued. Older patients were at higher risk than younger patients, both showing a peak at 1 year. Another peak at 6 to 8 years was observed in younger patients. Male patients showed a higher risk than female patients, and patients with synchronous lesions showed a markedly higher hazard rate than those without, with two distinct peaks around 1 and 9 years after surgery.

CONCLUSIONS

Intensive colonoscopic surveillance is recommended after surgery for CRC during the first 2 to 3 years, and if the patient is under 60 years old and has concomitant CRC or HGA, surveillance is also recommended at 6 to 8 years after surgery.

Risk of post colonoscopy colorectal cancer following screening colonoscopy with low-risk or no adenomas: A population-based study

AIM

In the Danish faecal occult blood test based bowel cancer screening programme, the first round was rolled out over 4 years. After roll-out, the planned faecal test recall procedure for individuals with either no or low risk adenomas at colonoscopy is 8 and 2 years, respectively. Here, we aimed to investigate the post colonoscopy colorectal cancer incidence in these two groups.

METHODS

All Danish screening individuals from 2014 to 2015 with a positive faecal test and either no or low risk adenomas at colonoscopy were included and followed for 3 years post screening for the event of colorectal cancer through national registries.

RESULTS

Out of 533,023 submitted faecal tests and 36,673 positive tests, 17,627 had no or low risk adenomas. We identified 60 (0.34%) individuals diagnosed with colorectal cancer within 3 years, 18 (0.29%) in the low risk adenoma group, and 42 (0.37%) in the no adenomas group (p = 0.44). Advancing age (HR = 1.079, p < 0.001) and higher faecal test value (HR = 1.001, p = 0.002) increased hazard of colorectal cancer occurrence, whereas male sex (HR = 1.3, p = 0.308) and having low risk adenomas (HR = 0.729, p = 0.264) did not.

CONCLUSION

We found no difference in post colonoscopy colorectal cancer occurrence between individuals with either no or low risk adenomas. Instead, advancing age and increased faecal test value was associated with a higher risk of post colonoscopy colorectal cancer.

Evaluation of global and intragenic hypomethylation in colorectal adenomas improves patient stratification and colorectal cancer risk prediction

Background

Aberrant DNA hypomethylation of the long interspersed nuclear elements (LINE-1 or L1) has been recognized as an early event of colorectal transformation. Simultaneous genetic and epigenetic analysis of colorectal adenomas may be an effective and rapid strategy to identify key biological features leading to accelerated colorectal tumorigenesis. In particular, global and/or intragenic LINE-1 hypomethylation of adenomas may represent a helpful tool for improving colorectal cancer (CRC) risk stratification of patients after surgical removal of polyps. To verify this hypothesis, we analyzed a cohort of 102 adenomas derived from 40 high-risk patients (who developed CRC in a post-polypectomy of at least one year) and 43 low-risk patients (who did not develop CRC in a post-polypectomy of at least 5 years) for their main pathological features, the presence of hotspot variants in driver oncogenes (KRAS, NRAS, BRAF and PIK3CA), global (LINE-1) and intragenic (L1-MET) methylation status.

Results

In addition to a significantly higher adenoma size and an older patients’ age, adenomas from high-risk patients were more hypomethylated than those from low-risk patients for both global and intragenic LINE-1 assays. DNA hypomethylation, measured by pyrosequencing, was independent from other parameters, including the presence of oncogenic hotspot variants detected by mass spectrometry. Combining LINE-1 and L1-MET analyses and profiling the samples according to the presence of at least one hypomethylated assay improved the discrimination between high and low risk lesions (p = 0.005). Remarkably, adenomas with at least one hypomethylated assay identified the patients with a significantly (p < 0.001) higher risk of developing CRC. Multivariable analysis and logistic regression evaluated by the ROC curves proved that methylation status was an independent variable improving cancer risk prediction (p = 0.02).

Conclusions

LINE-1 and L1-MET hypomethylation in colorectal adenomas are associated with a higher risk of developing CRC. DNA global and intragenic hypomethylation are independent markers that could be used in combination to successfully improve the stratification of patients who enter a colonoscopy surveillance program.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01135-0.

Genotype-Based Gene Expression in Colon Tissue-Prediction Accuracy and Relationship with the Prognosis of Colorectal Cancer Patients

Colorectal cancer (CRC) survival has environmental and inherited components. The expression of specific genes can be inferred based on individual genotypes—so called expression quantitative trait loci. In this study, we used the PrediXcan method to predict gene expression in normal colon tissue using individual genotype data from 91 CRC patients and examined the correlation ρ between predicted and measured gene expression levels. Out of 5434 predicted genes, 58% showed a negative ρ value and only 16% presented a ρ higher than 0.10. We subsequently investigated the association between genotype-based gene expression in colon tissue for genes with ρ > 0.10 and survival of 4436 CRC patients. We identified an inverse association between the predicted expression of ARID3B and CRC-specific survival for patients with a body mass index greater than or equal to 30 kg/m² (HR (hazard ratio) = 0.66 for an expression higher vs. lower than the median, p = 0.005). This association was validated using genotype and clinical data from the UK Biobank (HR = 0.74, p = 0.04). In addition to the identification of ARID3B expression in normal colon tissue as a candidate prognostic biomarker for obese CRC patients, our study illustrates the challenges of genotype-based prediction of gene expression, and the advantage of reassessing the prediction accuracy in a subset of the study population using measured gene expression data.

Clinical-Grade Detection of Microsatellite Instability in Colorectal Tumors by Deep Learning

BACKGROUND & AIMS

Microsatellite instability (MSI) and mismatch-repair deficiency (dMMR) in colorectal tumors are used to select treatment for patients. Deep learning can detect MSI and dMMR in tumor samples on routine histology slides faster and less expensively than molecular assays. However, clinical application of this technology requires high performance and multisite validation, which have not yet been performed.

METHODS

We collected H&E-stained slides and findings from molecular analyses for MSI and dMMR from 8836 colorectal tumors (of all stages) included in the MSIDETECT consortium study, from Germany, the Netherlands, the United Kingdom, and the United States. Specimens with dMMR were identified by immunohistochemistry analyses of tissue microarrays for loss of MLH1, MSH2, MSH6, and/or PMS2. Specimens with MSI were identified by genetic analyses. We trained a deep-learning detector to identify samples with MSI from these slides; performance was assessed by cross-validation (N = 6406 specimens) and validated in an external cohort (n = 771 specimens). Prespecified endpoints were area under the receiver operating characteristic (AUROC) curve and area under the precision-recall curve (AUPRC).

RESULTS

The deep-learning detector identified specimens with dMMR or MSI with a mean AUROC curve of 0.92 (lower bound, 0.91; upper bound, 0.93) and an AUPRC of 0.63 (range, 0.59-0.65), or 67% specificity and 95% sensitivity, in the cross-validation development cohort. In the validation cohort, the classifier identified samples with dMMR with an AUROC of 0.95 (range, 0.92-0.96) without image preprocessing and an AUROC of 0.96 (range, 0.93-0.98) after color normalization.

CONCLUSIONS

We developed a deep-learning system that detects colorectal cancer specimens with dMMR or MSI using H&E-stained slides; it detected tissues with dMMR with an AUROC of 0.96 in a large, international validation cohort. This system might be used for high-throughput, low-cost evaluation of colorectal tissue specimens.

Polymorphisms in the Angiogenesis-Related Genes EFNB2, MMP2 and JAG1 Are Associated with Survival of Colorectal Cancer Patients

An individual’s inherited genetic variation may contribute to the ‘angiogenic switch’, which is essential for blood supply and tumor growth of microscopic and macroscopic tumors. Polymorphisms in angiogenesis-related genes potentially predispose to colorectal cancer (CRC) or affect the survival of CRC patients. We investigated the association of 392 single nucleotide polymorphisms (SNPs) in 33 angiogenesis-related genes with CRC risk and survival of CRC patients in 1754 CRC cases and 1781 healthy controls within DACHS (Darmkrebs: Chancen der Verhütung durch Screening), a German population-based case-control study. Odds ratios and 95% confidence intervals (CI) were estimated from unconditional logistic regression to test for genetic associations with CRC risk. The Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% CIs for survival. Multiple testing was adjusted for by a false discovery rate. No variant was associated with CRC risk. Variants in EFNB2, MMP2 and JAG1 were significantly associated with overall survival. The association of the EFNB2 tagging SNP rs9520090 (p < 0.0001) was confirmed in two validation datasets (p-values: 0.01 and 0.05). The associations of the tagging SNPs rs6040062 in JAG1 (p-value 0.0003) and rs2241145 in MMP2 (p-value 0.0005) showed the same direction of association with overall survival in the first and second validation sets, respectively, although they did not reach significance (p-values: 0.09 and 0.25, respectively). EFNB2, MMP2 and JAG1 are known for their functional role in angiogenesis and the present study points to novel evidence for the impact of angiogenesis-related genetic variants on the CRC outcome.

Long-Term Colorectal Cancer Incidence and Mortality After a Single Negative Screening Colonoscopy

BACKGROUND

Current guidelines recommend a 10-year interval between screening colonoscopies, but evidence is limited.

OBJECTIVE

To assess the long-term risk for colorectal cancer (CRC) and death from CRC after a high- and low-quality single negative screening colonoscopy.

DESIGN

Observational study.

SETTING

Polish Colonoscopy Screening Program.

PARTICIPANTS

Average-risk individuals aged 50 to 66 years who had a single negative colonoscopy (no neoplastic findings).

MEASUREMENTS

Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) of CRC after high- and low-quality single negative screening colonoscopy. High-quality colonoscopy included a complete examination, with adequate bowel preparation, performed by endoscopists with an adenoma detection rate of 20% or greater.

RESULTS

Among 165 887 individuals followed for up to 17.4 years, CRC incidence (0.28 [95% CI, 0.25 to 0.30]) and mortality (0.19 [CI, 0.16 to 0.21]) were 72% and 81% lower, respectively, than in the general population. High-quality examination resulted in 2-fold lower CRC incidence (SIR, 0.16 [CI, 0.13 to 0.20]) and mortality (SMR, 0.10 [CI, 0.06 to 0.14]) than low-quality examination (SIR, 0.32 [CI, 0.29 to 0.35]; SMR, 0.22 [CI, 0.18 to 0.25]). In multivariable analysis, the hazard ratios for CRC incidence after high-quality versus low-quality colonoscopy were 0.55 (CI, 0.35 to 0.86) for 0 to 5 years, 0.54 (CI, 0.38 to 0.77) for 5.1 to 10 years, and 0.46 (CI, 0.25 to 0.86) for 10 to 17.4 years. Only after high-quality colonoscopy did the SIR and SMR for 10.1 to 17.4 years of follow-up not differ compared with earlier observation periods.

LIMITATION

The general population was used as the comparison group.

CONCLUSION

A single negative screening colonoscopy was associated with reduced CRC incidence and mortality for up to 17.4 years. Only high-quality colonoscopy yielded profound and stable reductions in CRC incidence and mortality throughout the entire follow-up.

PRIMARY FUNDING SOURCE

Polish Ministry of Health.

A survey on colonoscopy shows poor understanding of its protective value and widespread misconceptions across Europe

Background

Colonoscopy is a valuable screening tool for colorectal cancer. However, patients experience anxiety when faced with attending a first colonoscopy, and negative attitudes may contribute to non-attendance. Few studies in Europe have explored these attitudes, despite increasing colorectal cancer incidence.

Study aim

We conducted an online survey of the public in five European Union countries (France, Germany, Italy, Spain, and the UK), with the aim of understanding public knowledge of, perceptions of, and attitudes towards, colonoscopy and bowel preparation, amongst colonoscopy-naïve respondents. Attitudes towards colonoscopy were also gathered from colonoscopy-experienced patients.

Methods

Survey answers were gathered from 2,500 colonoscopy-naïve respondents and 500 colonoscopy-experienced patients, divided equally between countries.

Results

Across Europe, 72% of colonoscopy-naïve respondents showed receptiveness to colonoscopy if advised by their doctor to receive one, but only 45% understood its use to prevent colorectal cancer. Forty-three percent of colonoscopy-experienced respondents would still be embarrassed about having another colonoscopy, although 59% said that the experience had been better than expected. Colonoscopy-experienced respondents had greater aversion to bowel preparation than colonoscopy-naïve respondents (47% vs 26%), and 67% of colonoscopy-naïve respondents thought that only 1 litre of bowel preparation or less is required. Italians and the Spanish wanted more information than on average in Europe, while Germans had more realistic expectations of bowel preparation.

Discussion

There are perceptual gaps amongst the public around the purpose of colonoscopies, the subjective experience of the colonoscopy procedure, and the quantity of bowel preparation needed. These concerns could be mitigated by better education and using lower-volume bowel preparation techniques.

Conclusion

Europeans would have a colonoscopy, but its preventive medical purpose is poorly understood and there are misconceptions around the process. Further education about the procedure, its benefits and bowel preparation is vital to improve understanding and compliance.

Microsimulation Modeling in Oncology

PURPOSE

Microsimulation is a modeling technique that uses a sample size of individual units (microunits), each with a unique set of attributes, and allows for the simulation of downstream events on the basis of predefined states and transition probabilities between those states over time. In this article, we describe the history of the role of microsimulation in medicine and its potential applications in oncology as useful tools for population risk stratification and treatment strategy design for precision medicine.

METHODS

We conducted a comprehensive and methodical search of the literature using electronic databases-Medline, Embase, and Cochrane-for works published between 1985 and 2016. A medical subject heading search strategy was constructed for Medline searches by using a combination of relevant search terms, such as "microsimulation model medicine," "multistate modeling cancer," and "oncology."

RESULTS

Microsimulation modeling is particularly useful for the study of optimal intervention strategies when randomized control trials may not be feasible, ethical, or practical. Microsimulation models can retain memory of prior behaviors and states. As such, it allows an explicit representation and understanding of how various processes propagate over time and affect the final outcomes for an individual or in a population.

CONCLUSION

A well-calibrated microsimulation model can be used to predict the outcome of the event of interest for a new individual or subpopulations, assess the effectiveness and cost effectiveness of alternative interventions, and project the future disease burden of oncologic diseases. In the growing field of oncology research, a microsimulation model can serve as a valuable tool among the various facets of methodology available.

Colonoscopic withdrawal time and adenoma detection in the right colon

Shorter colonoscopic withdrawal time (CWT) has been associated with lower adenoma detection rate (ADR), which can increase the risk of interval colorectal cancer (ICC) that commonly arises in the right colon (RC). Therefore, a better ADR in the RC could decrease the incidence of ICC. We analyzed the relationship between CWT and ADR in the RC and entire colon.We retrospectively reviewed the patients who had undergone screening colonoscopy at Chungnam National University Hospital between March 2015 and February 2016. We enrolled 5370 patients in whom colonoscopies were performed by 7 gastroenterologists. We categorized patients into 4 groups in the RC and 6 groups in the entire colon by CWT. Multivariable analysis was used for detection of adenoma in the RC and entire colon.In the RC, the odds ratio (OR) of CWT longer than 3 minutes was 3.70, compared to CWT of <2 minutes [3.06-4.85, 95% confidence interval (CI), P < .001]. In the entire colon, the OR of CWT between 9 to 10 minutes and longer than 10 minutes was 3.34 [2.61-4.27, 95% CI, P < .001] and 3.49 [2.80-4.33, 95% CI, P < .001] compared to CWT of <6 minutes.Based on our result, we suggest that the optimum CWT in the RC should exceed 3 minutes, and considering the "ceiling effect," the optimum CWT in the entire colon should exceed 9 minutes.

Long-term risk of colorectal cancer after negative colonoscopy in a Danish gFOBT screening cohort

Faecal occult blood test (FOBT) screening for colorectal cancer (CRC) is implemented in several countries. Approximately half of all screen positive persons have negative colonoscopy, but consensus is lacking on how these persons should be followed up. Health authorities in Denmark and The Netherlands recommend suspending screening for 8-10 years, while patients in UK are invited to screening after 2 years. In this cohort-study, we followed 166,277 individuals invited to FOBT-screening in 2005-2006 and a reference group comprising the remaining 1,240,348 Danes of the same age. We linked Danish population and health service registers to obtain information about colonoscopy outcome and incident CRC. We estimated CRC risk by colonoscopy outcome (adenoma, other colorectal pathology or negative colonoscopy) for the reference group, the screening group, and subgroups. Persons with positive screening FOBT followed by negative colonoscopy had the same long-term CRC risk as persons with adenoma detected due to a positive screening FOBT (aHR 1.33, 95% CI: 0.65-2.71). We found no difference in the long-term CRC risk between persons with negative colonoscopy after a positive FOBT screening test and the unscreened reference population (aHR 1.05, 95% CI: 0.62-1.78). Since FOBT screen positive persons in our study remained at average risk of CRC despite of a negative index colonoscopy, we question the safety of suspending FOBT screening for this group. It needs to be monitored whether recent efforts to improve colonoscopy quality have been successful in ensuring low CRC risk after negative colonoscopy also in FOBT positive persons.

LINE-1 is preferentially hypomethylated within adenomatous polyps in the presence of synchronous colorectal cancer

Background

Conventional tubular adenomas are frequently detected in patients undergoing average risk screening colonoscopy and are over-represented in patients who will develop colorectal cancer (CRC). Whether features of adenomas could serve as predictors of synchronous CRC is not known. Here, we investigate whether global methylation markers, including LINE-1, differ within adenomas in patients with and without synchronous CRC.

Methods

Colorectal tubular/tubulovillous adenomatous polyps in the absence (P group, n = 45) and in the presence of synchronous CRC (PC group, n = 32) were identified. Global methylation and demethylation by ELISA for 5-methylcytosine (5-mC) and 5-hydroxymethyl cytosine (5-hmC), respectively, were assessed in polyps and adjacent normal non-neoplastic tissue. LINE-1 hypomethylation was assessed by pyrosequencing of bisulfite-converted DNA as well.

Results

Global methylation (5-mC) showed no differences in overall methylation status in the adenomatous polyps in the two groups (5-mC relative to control %, PC group 0.117; P group 0.161, p = 0.148). Global hydroxymethylation 5-hmC was also not significantly different in adenomatous polyps of the PC group than in those of the P group (0.0059 vs 0.0097, p = 0.681). Similarly, global 5-hmC was not different between normal tissues from patients without neoplasia in comparison to those from CRC patients (0.0461 ± 0.080 vs 0.039 ± 0.159, p = 0.215). In contrast, adenomatous polyps of the PC group had lower levels of LINE-1 methylation compared to the adenomas in the P group (53.07 ± 4.5 vs 59.95 ± 5.4, p < 0.001). LINE-1 methylation was also significantly lower in the normal tissue from cancer patients compared to that from patients without any neoplasia (58.07 ± 3.78 vs 71.50 ± 6.47, p < 0.001).

Conclusions

LINE-1 hypomethylation of precancerous adenomas correlates with the presence of synchronous CRC. Measurement of DNA hypomethylation levels of colorectal adenomas by LINE-1 could have future implications in approaches to defining CRC risk in screening programs.

Risk and Characteristics of Postcolonoscopy Interval Colorectal Cancer after a Positive Fecal Test: A Nationwide Population-Based Study in Korea

Purpose

Fecal tests remain a mainstay of population-based colorectal cancer (CRC) screening programs worldwide. However, data on interval CRC (iCRC) arising after follow-up colonoscopy of a positive fecal test are scarce. We conducted a nationwide population-based study to reveal the risk and characteristics of iCRC in this setting.

Materials and Methods

We searched the National Cancer Screening Program for CRC database in Korea (2005-2010). Incidence of iCRC within the program was estimated, then Cox proportional-hazards regression analysis was performed to determine the independent predictors of iCRC. The clinical characteristics of iCRC were compared with screen-detected CRC (sCRC).

Results

We identified 280 iCRC among 150,660 negative colonoscopies as a follow-up exam to a positive fecal immunochemical test (FIT), and 2,427 sCRC. The overall incidence of iCRC was 0.49/1,000 person-years (95% confidence interval [CI], 0.48 to 0.51). iCRC was more likely to occur in men (adjusted hazard ratio [aHR], 1.79; 95% CI, 1.39 to 2.30) and elderly patients (aHR, 1.77; 95% CI, 1.38 to 2.28 in 65-74 years; aHR, 3.13, 95% CI, 2.13 to 4.60 in ≥ 75 years). The National Quality Improvement Program for colonoscopy reduced a short-term risk of iCRC (aHR, 0.48; 95% CI, 0.27 to 0.87). Compared with sCRC, iCRC was more likely to occur in the proximal colon, be diagnosed at the localized stage, and have a lower CRC mortality (32.7 vs. 17.4%, 56.8 vs. 34.1%, and 12.5 vs. 17.7%, respectively; all p < 0.05).

Conclusion

In a population-based CRC screening program with FIT, the burden of iCRC after follow-up colonoscopy was substantial. Men and elderly patients possess a significantly higher risk of iCRC.

Screening for colorectal cancer

This review will comprise a general overview of colorectal cancer (CRC) screening. We will cover the impact of CRC, CRC risk factors, screening modalities, and guideline recommendations for screening in average-risk and high-risk individuals. Based on this data, we will summarize our approach to CRC screening.

Prediction of colorectal cancer diagnosis based on circulating plasma proteins

Non-invasive detection of colorectal cancer with blood-based markers is a critical clinical need. Here we describe a phased mass spectrometry-based approach for the discovery, screening, and validation of circulating protein biomarkers with diagnostic value. Initially, we profiled human primary tumor tissue epithelia and characterized about 300 secreted and cell surface candidate glycoproteins. These candidates were then screened in patient systemic circulation to identify detectable candidates in blood plasma. An 88-plex targeting method was established to systematically monitor these proteins in two large and independent cohorts of plasma samples, which generated quantitative clinical datasets at an unprecedented scale. The data were deployed to develop and evaluate a five-protein biomarker signature for colorectal cancer detection.

Evaluation of the diagnostic value of 64 simultaneously measured autoantibodies for early detection of gastric cancer

Autoantibodies against tumor-associated antigens (TAAs) have been suggested as biomarkers for early detection of gastric cancer. However, studies that systematically assess the diagnostic performance of a large number of autoantibodies are rare. Here, we used bead-based multiplex serology to simultaneously measure autoantibody responses against 64 candidate TAAs in serum samples from 329 gastric cancer patients, 321 healthy controls and 124 participants with other diseases of the upper digestive tract. At 98% specificity, sensitivities for the 64 tested autoantibodies ranged from 0–12% in the training set and a combination of autoantibodies against five TAAs (MAGEA4 + CTAG1 + TP53 + ERBB2_C + SDCCAG8) was able to detect 32% of the gastric cancer patients at a specificity of 87% in the validation set. Sensitivities for early and late stage gastric cancers were similar, while chronic atrophic gastritis, a precursor lesion of gastric cancer, was not detectable. However, the 5-marker combination also detected 26% of the esophageal cancer patients. In conclusion, the tested autoantibodies and combinations alone did not reach sufficient sensitivity for gastric cancer screening. Nevertheless, some autoantibodies, such as anti-MAGEA4, anti-CTAG1 or anti-TP53 and their combinations could possibly contribute to the development of cancer early detection tests (not necessarily restricted to gastric cancer) when being combined with other markers.

The European Society of Gastrointestinal Endoscopy Quality Improvement Initiative: developing performance measures

The European Society of Gastrointestinal Endoscopy (ESGE) and United European Gastroenterology (UEG) have a vision to create a thriving community of endoscopy services across Europe, collaborating with each other to provide high quality, safe, accurate, patient-centered and accessible endoscopic care. Whilst the boundaries of what can be achieved by advanced endoscopy are continually expanding, we believe that one of the most fundamental steps to achieving our goal is to raise the quality of everyday endoscopy. The development of robust, consensus- and evidence-based key performance measures is the first step in this vision. ESGE and UEG have identified quality of endoscopy as a major priority. This paper explains the rationale behind the ESGE Quality Improvement Initiative and describes the processes that were followed. We recommend that all units develop mechanisms for audit and feedback of endoscopist and service performance using the ESGE performance measures that will be published in future issues of this journal over the next year. We urge all endoscopists and endoscopy services to prioritize quality and to ensure that these performance measures are implemented and monitored at a local level, so that we can provide the highest possible care for our patients.

Ten-year incidence of colorectal cancer following a negative screening sigmoidoscopy: an update from the Colorectal Cancer Prevention (CoCaP) programme

OBJECTIVE

To examine the rates of colorectal cancer (CRC) following a negative screening sigmoidoscopy.

DESIGN

Cohort study.

SETTING

An integrated healthcare delivery organisation in California, USA.

PARTICIPANTS

72,483 men and women aged 50 years and above who had a negative screening sigmoidoscopy between 1994 and 1996. Those at elevated risk of CRC due to inflammatory bowel disease, prior polyps or CRC, or a strong family history of CRC were excluded.

MAIN OUTCOME MEASURES

Incidence rates of distal and proximal CRC. Standardised Incidence Ratios were used to compare annual incidence rates of distal and proximal CRC in the cohort to expected rates based on Surveillance, Epidemiology, and End Results data. Additionally, rate ratios (RR) and rate differences (RD) comparing the incidence rate of distal CRC in years 6+ postscreening with that in years 1-5 were calculated.

RESULTS

Incidence rates of distal CRC were lower than those in the San Francisco Bay area population at large during each of the first 10 years postsigmoidoscopy screening. However, the incidence of distal CRC rose steadily, from 3 per 100,000 in the first year of follow-up to 40 per 100,000 in the 10th year. During the second half of follow-up, the rate of distal CRC was twice as high as in the first half (RR 2 .08, 95% CI 1.38 to 3.16; RD 14 per 100,000 person-years, 95% CI 6 to 22).

CONCLUSIONS

Though still below population levels, the incidence of CRC during years 6-10 following a negative sigmoiodoscopy is appreciably higher than during the first 5 years.

Interval colorectal carcinoma: An unsolved debate

Colorectal carcinoma (CRC), as the third most common new cancer diagnosis, poses a significant health risk to the population. Interval CRCs are those that appear after a negative screening test or examination. The development of interval CRCs has been shown to be multifactorial: location of exam-academic institution versus community hospital, experience of the endoscopist, quality of the procedure, age of the patient, flat versus polypoid neoplasia, genetics, hereditary gastrointestinal neoplasia, and most significantly missed or incompletely excised lesions. The rate of interval CRCs has decreased in the last decade, which has been ascribed to an increased understanding of interval disease and technological advances in the screening of high risk individuals. In this article, we aim to review the literature with regard to the multifactorial nature of interval CRCs and provide the most recent developments regarding this important gastrointestinal entity.

Patient- and procedure-related factors affecting proximal and distal detection rates for polyps and adenomas: results from 1603 screening colonoscopies

BACKGROUND

Screening colonoscopy is less effective in reducing the incidence of proximal compared to distal colorectal cancer, presumably because of missed adenomas and advanced lesions during endoscopy. Thus, effectiveness and success of colorectal cancer (CRC) screening programs depend decisively on the quality of the endoscopic procedures.

METHODS

A retrospective analysis of 1603 average risk screening colonoscopies to calculate and to identify determinants of separate detection rates for proximally and distally located polyps, adenomas, and advanced adenomas was performed.

RESULTS

56.1 % of 1603 individuals included were men, and the mean age was 60.2 ± 10.2 years. Distal detection rates were markedly higher compared to proximal detection rates for polyps (40.9 vs. 23.8 %), adenomas (21.3 vs. 16.2 %), and advanced adenomas (4.0 vs. 2.0 %). A gradual increase in detection rates with increasing age was found for proximal and distal localization. Gender difference was also seen for polyps and adenomas, but not for advanced adenomas. In multivariate analysis, age <65.0 years and female gender were independently associated with a lower separate polyp detection rate (PDR) and adenoma detection rate (ADR). The use of propofol was the only procedure-related variable significantly associated with higher polyp detection rate.

CONCLUSION

Since age and gender affect detection rates of proximally and distally located polyps and adenomas, the requirement of a specific gender-related limit in total detection rates may be insufficient as a quality indicator for screening colonoscopies.

Methylation pattern of ALX4 gene promoter as a potential biomarker for blood-based early detection of colorectal cancer

BACKGROUND

To develop a non-invasive screening method for colorectal cancer, we evaluated the methylation of ALX4 gene promoter in serum samples from patients with colorectal cancer (CRC) and equal number of healthy individuals.

MATERIALS AND METHODS

In serum samples from 25 patients with colorectal cancer and 25 healthy control subjects, isolated serum free-floating DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction (MSP) with primers specific for methylated or unmethylated promoter CpG island sequences of the ALX4 gene.

RESULTS

Methylation of the ALX4 gene promoter was present in the serum DNA of patients with adenoma and colorectal cancer. A sensitivity of 68% and specificity of 88% were achieved in the detection of promoter methylation in colorectal neoplasia samples. The difference in methylation status of the ALX4 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P < 0.001).

CONCLUSIONS

The results indicate that this serum free DNA test of methylation of the ALX4 gene promoter is a sensitive and specific method. Therefore in combination with other useful markers it seems ALX4 has the potential of a clinically useful test for the early detection of colorectal cancer.

Quality measures for colonoscopy: where should we be in 2015?

Colonoscopy is an effective colorectal cancer (CRC) screening and prevention modality as evidenced by a 30-year decline in both incident colon cancers and CRC mortality in the USA. The USA is unique among the developed countries in its use of colonoscopy as the most common method to screen for CRC. Individual patients gain maximum value from their colonoscopy experience when they undergo a comfortable exam that is of highest quality, during which all polyps are found and removed safely and completely, where their physicians adhere to all appropriate guidelines and when they (or their insurance) pay a reasonable amount for their care. Colonoscopy "quality" publications to date have been focused on how to improve the individual physician's procedural results and this narrow focus has birthed an entire industry (usually based on entering data into a national registry) that is focused on demonstrating a physician's success in achieving a certain threshold performance metric that is usually (a) marginally related to true health outcomes, (b) can be captured from the myriad electronic medical records (EMR) in existence today, and (c) is attainable by most practicing gastroenterologists. Medical societies have worked diligently to link these registries and recognition programs to commercial or federal payer-based incentive funds. As health care reform drives massive consolidation of delivery systems and reimbursement moves toward population-level two-sided financial risk models, our current measurement infrastructure will become irrelevant. The focus on "value" and the Triple Aim will drive development of a radically different approach. The process by which individual gastroenterologists (or practices) demonstrate the value of colonoscopy as a colorectal cancer (CRC) prevention tool will change dramatically. Essentially, six measures will be reported by a health system: (1) percent of eligible population screened, (2) access to colonoscopy services, (3) complication rates, (4) patient experience scores, (5) episode (bundle) cost, and (6) frequency with which interval cancers occur after a colonoscopy exam (likely using a 3-year interval). Each gastroenterologist within a health system will be evaluated using familiar metrics (cecal intubation, withdrawal time, adenoma detection rate) but these results will likely be used internally to determine whether they are included in a provider network. If they continue to be used in commercial or government incentive programs, then the enterprise electronic medical record will be constructed to populate external programs directly. Population-level metrics (listed above) will determine whether higher cost provider networks (including academic health centers) who might deliver better health outcomes can compete successfully for regional market share with lower cost providers. This article will outline a plan for a health system initiative focused on provision of colonoscopy for CRC prevention; a plan that will help a group of gastroenterologists (whether employed within a health system or independent) demonstrate why they should be a preferred provider and whether they will survive and thrive in the coming world of accountable care.

Comparing the effectiveness of competing tests for reducing colorectal cancer mortality: a network meta-analysis

BACKGROUND

Comparative effectiveness data pertaining to competing colorectal cancer (CRC) screening tests do not exist but are necessary to guide clinical decision making and policy.

OBJECTIVE

To perform a comparative synthesis of clinical outcomes studies evaluating the effects of competing tests on CRC-related mortality.

DESIGN

Traditional and network meta-analyses. Two reviewers identified studies evaluating the effect of guaiac-based fecal occult blood testing (gFOBT), flexible sigmoidoscopy (FS), or colonoscopy on CRC-related mortality.

INTERVENTIONS

gFOBT, FS, colonoscopy.

MAIN OUTCOME MEASUREMENTS

Traditional meta-analysis was performed to produce pooled estimates of the effect of each modality on CRC mortality. Bayesian network meta-analysis (NMA) was performed to indirectly compare the effectiveness of screening modalities. Multiple sensitivity analyses were performed.

RESULTS

Traditional meta-analysis revealed that, compared with no intervention, colonoscopy reduced CRC-related mortality by 57% (relative risk [RR] 0.43; 95% confidence interval [CI], 0.33-0.58), whereas FS reduced CRC-related mortality by 40% (RR 0.60; 95% CI, 0.45-0.78), and gFOBT reduced CRC-related mortality by 18% (RR 0.82; 95% CI, 0.76-0.88). NMA demonstrated nonsignificant trends favoring colonoscopy over FS (RR 0.71; 95% CI, 0.45-1.11) and FS over gFOBT (RR 0.74; 95% CI, 0.51-1.09) for reducing CRC-related deaths. NMA-based simulations, however, revealed that colonoscopy has a 94% probability of being the most effective test for reducing CRC mortality and a 99% probability of being most effective when the analysis is restricted to screening studies.

LIMITATIONS

Randomized trials and observational studies were combined within the same analysis.

CONCLUSION

Clinical outcomes studies demonstrate that gFOBT, FS, and colonoscopy are all effective in reducing CRC-related mortality. Network meta-analysis suggests that colonoscopy is the most effective test.

Diagnostic yield of third eye retroscope on adenoma detection during colonoscopy: A systematic review and meta-analysis

AIM: To determine the diagnostic yield of the “third eye retroscope”, on adenoma detection rate during screening colonoscopy.

METHODS: The “third eye retroscope” when used with standard colonoscopy provides an additional retrograde view to visualize lesions on the proximal aspects of folds and flexures. We searched MEDLINE (PubMed and Ovid), SCOPUS (including MEDLINE and EMBASE databases), Cochrane Database of Systemic Reviews, Google Scholar, and CINAHL Plus databases to identify studies that evaluated diagnostic yield of “third eye retroscope” during screening colonoscopy. DerSimonian Laird random effects model was used to generate the overall effect for each outcome. We evaluated statistical heterogeneity among the studies by using the Cochran Q statistic and quantified by I² statistics.

RESULTS: Four distinct studies with a total of 920 patients, mean age 59.83 (95%CI: 56.77-62.83) years, were included in the review. The additional adenoma detection rate (AADR) defined as the number of additional adenomas identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.9% (95%CI: 7.3-43.9). AADR for right and left colon were 13.9% (95%CI: 9.4-20) and 10.7 (95%CI: 1.9-42), respectively. AADR for polyps ≥ 6 mm and ≥ 10 mm were 24.6% (95%CI: 16.6-34.9) and 24.2% (95%CI: 12.9-40.8), respectively. The additional polyp detection rate defined as the number of additional polyps identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.8% (95%CI: 7.9-41.8). There were no complications reported with use of “third eye retroscope” device.

CONCLUSION: The “third eye retroscope” device when used with standard colonoscopy is safe and detects 19.9% additional adenomas, compared to standard colonoscopy alone.

Factors that determine prolonged cecal intubation time during colonoscopy: impact of visceral adipose tissue

OBJECTIVE

Various factors including age, sex, body mass index (BMI) and history of operation have been linked to the colonoscopic intubation time. The aims of this study were to identify the factors predicting cecal intubation time (CIT) and to evaluate the effect of the visceral adipose tissue (VAT) area on CIT.

MATERIAL AND METHODS

A total of 1386 consecutive subjects who underwent colonoscopy and abdominal CT on the same day for a health checkup at a single health care center in Korea from August to December 2011 were studied prospectively. Age, sex, BMI, height, waist circumference, history of operation, symptoms of irritable bowel syndrome, bowel preparation status, experience of colonoscopists, VAT amount on abdominal CT and time required to reach the cecum were analyzed.

RESULTS

The mean age of the subjects was 53.0 ± 9.6 years, and 63.5% were male. The median CIT was 271 s. Univariate analyses showed that female gender, old age, shorter height, lower BMI, prior history of surgery and lower VAT were associated with longer CIT. To adjust for confounding effects of the gender, we investigated the genders separately in multivariate analysis. Older age and lower VAT were associated with prolonged CIT. However, the significance of association of VAT on prolonged CIT disappeared in women.

CONCLUSION

This study demonstrates that CIT is prolonged by lower VAT area in men. This is the first study to demonstrate a direct association between VAT area and CIT.

Establishing a biological profile for interval colorectal cancers

Colorectal cancer (CRC) remains the second leading cause of cancer-related deaths in North America. Screening for CRC and its precursor lesions is highly effective in reducing the incidence and deaths due to the disease. However, there remain a substantial number of individuals who are diagnosed with CRC soon after a negative/clearing colonoscopy with no documented evidence of CRC. The occurrence of these interval CRCs (I-CRCs) reduces the effectiveness of CRC screening and detection tests and has only recently attracted wide spread attention. I-CRCs can be subdivided into those that occur most likely due to the failure of the colonoscopy examination (missed CRC and CRC that developed from missed or incompletely resected precursor lesions) and those that develop rapidly after the colonoscopy (de novo I-CRCs). In this review, we discuss the current literature and present both the clinical and biological factors that have been identified to account for I-CRCs, with a particular focus on the aberrant molecular features that are candidate causative agents for I-CRCs. We conclude additional studies are required to fully understand the molecular features that lead to the development of I-CRCs, which in turn is essential to develop measures to prevent the occurrence of this group of CRCs and thereby improve CRC screening and detection strategies.

Attendance and yield over three rounds of population-based fecal immunochemical test screening

OBJECTIVES

Fecal immunochemical test (FIT) screening for colorectal cancer (CRC) requires timely successive rounds for an optimal preventive effect. However, data on attendance and trend in yield over multiple rounds of FIT screening are limited. We therefore conducted a consecutive third round of FIT screening in a population-based CRC screening trial.

METHODS

Average-risk subjects aged 50-74 years were approached for three rounds of 1-sample FIT (OC-sensor) screening. Subjects with a hemoglobin level ≥50 ng/ml (≥10 μg Hb/g) feces were referred for colonoscopy. Subjects with a positive FIT in previous rounds were not re-invited for FIT screening.

RESULTS

In the first round, 7,501 subjects were invited. The participation rate was 62.6% in the first round, 63.2% in the second round, and 68.3% in the third round (P<0.001). In total, 73% (5,241/7,229) of all eligible subjects participated in at least one of three rounds. The positivity rate was significantly higher in the first (8.4%) round compared with the second (6.0%) and third (5.7%) screening rounds (P<0.001). The detection rate of advanced neoplasia (AN) declined from the first round to subsequent rounds (round 1: 3.3%; round 2: 1.9%; and round 3: 1.3%; P<0.001). The positive predictive value for AN was 40.7% in the first screening round, 33.2% in the second screening round, and 24.0% in the third screening round (P<0.001).

CONCLUSIONS

Repeated biennial FIT screening is acceptable with increased participation in successive screening rounds, and >70% of all eligible subjects participating at least once over three rounds. The decline in screen-detected AN over three screening rounds is compatible with a decreased prevalence of AN as a result of repeated FIT screening. These findings provide strong evidence for the effectiveness of FIT screening and stress the importance of ongoing research over multiple screening rounds.

Colonoscopy reduced distal colorectal cancer risk and excess cancer risk associated with family history

PURPOSE

Colonoscopy efficacy at preventing proximal colorectal cancer (CRC) is questioned, and little is known about efficacy in high-risk versus medium-risk populations. We investigated the relationship between colonoscopy screening, family history of colorectal cancer (FHCC), and CRC risk by site.

METHODS

Among 92,078 women of the E3N prospective cohort, 692 CRCs have been diagnosed after a median follow-up of 15.4 years. Cox proportional hazard models estimated adjusted hazards ratios according to subsites of cancer and FHCC.

RESULTS

A personal history of colonoscopy (PHC; n = 37,470) was associated with decreased rectal and distal colon cancer risks (hazard ratio (HR) = 0.57; 95% Confidence Interval (CI) = 0.42-0.78 and HR = 0.37; 95% CI = 0.26-0.52, respectively), but not proximal colon cancer risk (HR = 0.87; 95% CI = 0.64-1.18). In women with no prior colonoscopy, those with FHCC had a 80% higher CRC risk than those without FHCC. In women with previous colonoscopy, CRC risk was similar in women with and without FHCC (p for interaction = 0.04).

CONCLUSIONS

Results showed colonoscopy ability to prevent distal cancers, but not proximal cancers in women. Colonoscopy screening also reduced the excess risk of women with FHCC to that of women with no FHCC.

Primary and secondary prevention of colorectal cancer

INTRODUCTION

Cancer is a worldwide problem as it will affect one in three men and one in four women during their lifetime. Colorectal cancer (CRC) is the third most frequent cancer in men, after lung and prostate cancer, and is the second most frequent cancer in women after breast cancer. It is also the third cause of death in men and women separately, and is the second most frequent cause of death by cancer if both genders are considered together. CRC represents approximately 10% of deaths by cancer. Modifiable risk factors of CRC include smoking, physical inactivity, being overweight and obesity, eating processed meat, and drinking alcohol excessively. CRC screening programs are possible only in economically developed countries. However, attention should be paid in the future to geographical areas with ageing populations and a western lifestyle.19,20 Sigmoidoscopy screening done with people aged 55–64 years has been demonstrated to reduce the incidence of CRC by 33% and mortality by CRC by 43%.

OBJECTIVE

To assess the effect on the incidence and mortality of CRC diet and lifestyle and to determine the effect of secondary prevention through early diagnosis of CRC.

METHODOLOGY: A comprehensive search of Medline and Pubmed articles related to primary and secondary prevention of CRC and subsequently, a meta-analysis of the same blocks are performed.

RESULTS

225 articles related to primary or secondary prevention of CRC were retrieved. Of these 145 were considered valid on meta-analysis: 12 on epidemiology, 56 on diet and lifestyle, and over 77 different screenings for early detection of CRC. Cancer is a worldwide problem as it will affect one in three men and one in four women during their lifetime. There is no doubt whatsoever which environmental factors, probably diet, may account for these cancer rates. Excessive alcohol consumption and cholesterol-rich diet are associated with a high risk of colon cancer. A diet poor in folic acid and vitamin B6 is also associated with a higher risk of developing colon cancer with an overexpression of p53. Eating pulses at least three times a week lowers the risk of developing colon cancer by 33%, after eating less meat, while eating brown rice at least once a week cuts the risk of CRC by 40%. These associations suggest a dose–response effect. Frequently eating cooked green vegetables, nuts, dried fruit, pulses, and brown rice has been associated with a lower risk of colorectal polyps. High calcium intake offers a protector effect against distal colon and rectal tumors as compared with the proximal colon. Higher intake of dairy products and calcium reduces the risk of colon cancer. Taking an aspirin (ASA) regularly after being diagnosed with colon cancer is associated with less risk of dying from this cancer, especially among people who have tumors with COX-2 overexpression.16 Nonetheless, these data do not contradict the data obtained on a possible genetic predisposition, even in sporadic or non-hereditary CRC. CRC is susceptible to screening because it is a serious health problem given its high incidence and its associated high morbidity/mortality.

CONCLUSIONS

(1) Cancer is a worldwide problem. (2) A modification of diet and lifestyle could reduce morbidity and mortality. (3) Early detection through screening improves prognosis and reduces mortality.

Systematic review with meta-analysis: the incidence of advanced neoplasia after polypectomy in patients with and without low-risk adenomas

BACKGROUND

Patients with one to two tubular adenomas <1 cm in size without high-grade dysplasia (low-risk group) are considered at low risk for colorectal cancer. However, it is uncertain whether they have the same risk of subsequent advanced neoplasia as those with no neoplasia at baseline colonoscopy.

AIM

To compare incidence of metachronous advanced neoplasia between patients in the low-risk adenoma group and those without neoplasia at index colonoscopy.

METHODS

Relevant publications were identified by MEDLINE/EMBASE and other databases for the period 1992-2013. Studies comparing the incidence of post-polypectomy advanced neoplasia (adenomas ≥10 mm/high-grade dysplasia/villous or cancer) between the low-risk group and patients without colorectal neoplasia at the first colonoscopy were included. Detection rates for advanced neoplasia at endoscopic surveillance were extracted. Study quality was ascertained according to Newcastle-Ottawa Scale. Forest plot was produced based on random-effect models. Inter-study heterogeneity was assessed using the I(2) statistic.

RESULTS

Seven studies provided data on 11 387 patients. Mean surveillance periods ranged between 2 and 5 years. Altogether, 267 patients with post-polypectomy advanced neoplasia were detected in the two groups. The incidence of advanced neoplasia was 1.6% (119/7308) in those without neoplasia and 3.6% (148/4079) in those with low-risk adenoma, respectively, corresponding to a relative risk of 1.8 (95% CI: 1.3-2.6). Inter-study heterogeneity was only moderate (I(2) : 37%). No publication bias was present.

CONCLUSIONS

Patients with low-risk adenomas at baseline had a higher risk of metachronous advanced neoplasia than the group with no adenomas at baseline, though the absolute risk was low in both groups.

Ethical issues in colorectal cancer screening

In many countries, colorectal cancer screening is currently an established population screening program due to the evidence on its reduction of colorectal cancer mortality. There is general consensus that colorectal cancer screening meets the screening criteria as proposed by Wilson and Jungner. However, as for all population screening programs, colorectal cancer screening also has disadvantages and thereby entails ethical issues. There are the general issues concerning the introduction of screening programs (e.g. medicalization, overdiagnosis and overtreatment, information provision to screenees), evaluation of cancer screening programs (e.g. lead time and length bias), chosen screening method (e.g. false-positive and false-negative test results, reduction of all-cause mortality, choice between different screening methods). The different colorectal cancer screening methods and the ethical issues concerning colorectal cancer screening will be discussed in this review.

Comparative evaluation of nine faecal immunochemical tests for the detection of colorectal cancer

BACKGROUND

Faecal immunochemical tests (FITs) for haemoglobin are increasingly used for non-invasive screening for colorectal cancer (CRC) but large scale comparative studies of different FITs for detection of CRC, overall and by stage, are sparse. We aimed to determine and compare performance of different FITs for the detection of CRC, and to assess their stage-specific sensitivities.

MATERIAL AND METHODS

We assessed sensitivity, specificity and their corresponding 95% confidence intervals for six qualitative FITs among 74 CRC cases (59% stage I or II cancers) and 1480 controls free of colorectal neoplasm. Overall and stage-specific receiver operating characteristic curves were derived for three quantitative FITs. The areas under the curves (AUCs) were calculated and compared.

RESULTS

Pairs of overall sensitivity and specificity of the qualitative FITs ranged from 66% and 96% to 92% and 62%, respectively. For the three quantitative tests, AUCs ranged from 0.90 to 0.92, with sensitivities ranging from 80% to 87% at cut-offs yielding 90% specificity. AUCs ranged from 0.85 to 0.92, 0.94 to 0.96, and 0.86 to 0.93 for stage I, stage II and advanced stages (stage III and IV) cancers, respectively. At a specificity of 90%, the tests detected 65%-85% of stage I cancers.

CONCLUSION

The diagnostic performance of FITs regarding detection of CRC is promising, even though the pre-defined cut-offs of some of the qualitative FITs need to be adjusted to limit false-positive rates in screening setting. At cut-off levels yielding 90% specificity, the quantitative tests detected the vast majority of CRCs, even at early stages.

Optimal withdrawal and examination in colonoscopy

The primary goal of most colonoscopies, whether performed for screening, surveillance, or diagnostic examinations (those performed for symptoms or positive screening tests other than colonoscopy) is the detection of neoplasia and its subsequent removal by either endoscopic polypectomy or referral for surgical resection. Unfortunately, colonoscopy has proved to be a highly operator-dependent procedure with regard to detection. Variable detection results in some of the cancers that occur in the interval before the next colonoscopy.