Global Prevalence of Colorectal Neoplasia: A Systematic Review and Meta-Analysis

Diagnostic yield from symptomatic lower gastrointestinal endoscopy in the UK: A British Society of Gastroenterology analysis using data from the National Endoscopy Database

BACKGROUND

The value of lower gastrointestinal endoscopy (LGIE; colonoscopy or sigmoidoscopy) relates to its ability to detect clinically relevant findings, predominantly cancers, preneoplastic polyps or inflammatory bowel disease. There are concerns that many LGIEs are performed on low-risk patients with limited benefit.

AIMS

To determine the diagnostic outcomes of LGIE for common symptoms.

METHODS

We performed a cross-sectional study of diagnostic LGIE between March 2019 and February 2020 using the UK National Endoscopy Database. We used mixed-effects logistic regression models, incorporating random (endoscopist) and fixed (symptoms, patient age, and sex) effects upon two dependent variables (large polyp [≥10 mm] and cancer diagnosis). Adjusted positive predictive values (aPPVs) were calculated.

RESULTS

We analysed 384,510 LGIEs; 33.2% were performed on patients aged under 50 and 53.6% on women. Regarding colonoscopies, the unadjusted PPV for cancer was 1.5% (95% CI: 1.4-1.5); higher for men than women (1.9% vs. 1.1%, p < 0.01). The PPV for large polyps was 3.2% (95% CI: 3.1-3.2). The highest colonoscopy cancer aPPVs were in the over 50s (1.9%) and in those with rectal bleeding (2.5%) or anaemia (2.1%). Cancer aPPVs for other symptoms were <1% despite representing 54.3% of activity. In patients under 50, aPPVs were 0.4% for cancer and 1.6% for large polyps. Results were similar for sigmoidoscopy.

CONCLUSIONS

Most colonoscopies were performed on patients with low-risk symptoms, where cancer risk was similar to the general population. Cancer and large polyp yield was highest in elderly patients with rectal bleeding or anaemia, although still fell short of FIT-based screening yields.

Mediterranean diet and colorectal adenomas: a systematic review and meta-analysis of observational studies

Colorectal adenomas (CRAs) are epithelial lesions of the large bowel that can develop into colorectal cancer. Some studies have shown an inverse association of the Mediterranean diet (MED) with adenoma, but the extent of the association is equivocal. Owing to the lack of meta-analytical evidence in the literature, we sought to assess the association between MED and CRAs by conducting a systematic review and meta-analysis. A comprehensive systematic literature search of observational studies was conducted via PubMed, Scopus, Google Scholar and Web of Sciences up to May 2023. Studies were included in our review if they evaluated the association between MED and CRA, following an observational study design. Six studies were included in this study. We found that adherence to MED was inversely associated with CRA risk (odds ratio, 0.79; confidence interval, 0.73-0.85); implying that higher adherence to MED could reduce the risk of CRA by ~21%. Stratification by the year of studies, sex, study design, country and exposure showed a significant association between MED and CRA. The results of the current study provide evidence of an inverse association between adherence to MED and CRAs.

Demographic and clinical profile of patients undergoing colonoscopy at a tertiary care center in Nepal: a retrospective cross-sectional study

Background

Colonoscopy is widely used as a tool for diagnosis, screening and treatment of various pathologies in the rectum, colon, and terminal ileum. The aim of this study is to evaluate the demographic, clinical, and histological parameters of the records of patients undergoing colonoscopy at a tertiary care hospital in Nepal.

Materials and methods

This retrospective cross-sectional study included the hospital records of all patients who underwent colonoscopy from 2015 to 2019 in a tertiary care centre in Nepal.

Results

A total of 1255 records were included in the study. The mean and standard deviation of age were 43.8 and 19 years, respectively. Among the total study population, 61.9% were males and 38.1% were females. Common indications for colonoscopy included lower gastrointestinal bleeding (27.7%), altered bowel habit (26.9%) and persistent or recurrent abdominal pain (17.3%). Only 3% of the patients who underwent colonoscopy had inadequate bowel preparation. The overall diagnostic yield of colonoscopy was 57.5%. Findings during colonoscopy included colorectal polyp (19.4%), internal haemorrhoids (8.2%) and colitis (6.5%). Having an age of 50 or more years was significantly associated with the presence of colorectal adenocarcinoma (P=0.017, χ2 test) with an odds ratio of 2.35 (95% CI: 1.14, 4.89). Furthermore, having a female sex was found to be significantly associated with the presence of colorectal adenocarcinoma (P=0.012, χ2 test) with an odds ratio of 2.43 (95% CI: 1.19, 4.97).

Conclusion

In the authors' study, a smaller proportion of the colonoscopies was aimed at screening for colorectal carcinoma (CRC), when compared to studies in developed countries. The sex predisposition of CRC in the authors' study is in contrast to the global trend. The authors recommend conducting studies to determine the risk factors and need for CRC screening in the Nepalese population.

Colon Polyp Surveillance: Separating the Wheat From the Chaff

One goal of colorectal cancer (CRC) screening is to prevent CRC incidence by removing precancerous colonic polyps, which are detected in up to 50% of screening examinations. Yet, the lifetime risk of CRC is 3.9%-4.3%, so it is clear that most of these individuals with polyps would not develop CRC in their lifetime. It is, therefore, a challenge to determine which individuals with polyps will benefit from follow-up, and at what intervals. There is some evidence that individuals with advanced polyps, based on size and histology, benefit from intensive surveillance. However, a large proportion of individuals will have small polyps without advanced histologic features (ie, "nonadvanced"), where the benefits of surveillance are uncertain and controversial. Demand for surveillance will further increase as more polyps are detected due to increased screening uptake, recent United States recommendations to expand screening to younger individuals, and emergence of polyp detection technology. We review the current understanding and clinical implications of the natural history, biology, and outcomes associated with various categories of colon polyps based on size, histology, and number. Our aims are to highlight key knowledge gaps, specifically focusing on certain categories of polyps that may not be associated with future CRC risk, and to provide insights to inform research priorities and potential management strategies. Optimization of CRC prevention programs based on updated knowledge about the future risks associated with various colon polyps is essential to ensure cost-effective screening and surveillance, wise use of resources, and inform efforts to personalize recommendations.

Fusobacterium nucleatum-induced imbalance in microbiome-derived butyric acid levels promotes the occurrence and development of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) ranks among the most prevalent malignant tumors globally. Recent reports suggest that Fusobacterium nucleatum (F. nucleatum) contributes to the initiation, progression, and prognosis of CRC. Butyrate, a short-chain fatty acid derived from the bacterial fermentation of soluble dietary fiber, is known to inhibit various cancers. This study is designed to explore whether F. nucleatum influences the onset and progression of CRC by impacting the intestinal metabolite butyric acid.

AIM

To investigate the mechanism by which F. nucleatum affects CRC occurrence and development.

METHODS

Alterations in the gut microbiota of BALB/c mice were observed following the oral administration of F. nucleatum. Additionally, DLD-1 and HCT116 cell lines were exposed to sodium butyrate (NaB) and F. nucleatum in vitro to examine the effects on proliferative proteins and mitochondrial function.

RESULTS

Our research indicates that the prevalence of F. nucleatum in fecal samples from CRC patients is significantly greater than in healthy counterparts, while the prevalence of butyrate-producing bacteria is notably lower. In mice colonized with F. nucleatum, the population of butyrate-producing bacteria decreased, resulting in altered levels of butyric acid, a key intestinal metabolite of butyrate. Exposure to NaB can impair mitochondrial morphology and diminish mitochondrial membrane potential in DLD-1 and HCT116 CRC cells. Consequently, this leads to modulated production of adenosine triphosphate and reactive oxygen species, thereby inhibiting cancer cell proliferation. Additionally, NaB triggers the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, blocks the cell cycle in HCT116 and DLD-1 cells, and curtails the proliferation of CRC cells. The combined presence of F. nucleatum and NaB attenuated the effects of the latter. By employing small interfering RNA to suppress AMPK, it was demonstrated that AMPK is essential for NaB's inhibition of CRC cell proliferation.

CONCLUSION

F. nucleatum can promote cancer progression through its inhibitory effect on butyric acid, via the AMPK signaling pathway.

Establishment and validation of symptomatic patients colorectal screening score for predicting colorectal neoplasia risk

OBJECTIVES

Currently, most colorectal neoplasia (CRN) screening strategies target asymptomatic individuals. However, studies on patients with non-specific gastrointestinal symptoms (NSGS) are limited. We aimed to develop a CRN risk score specifically for patients with NSGS.

METHODS

We prospectively enrolled patients who underwent initial colonoscopy between June 2020 and June 2021. A new risk scoring system was constructed and its applicability was evaluated.

RESULTS

A total of 1522 consecutive patients were enrolled, among whom 1016 symptomatic patients were randomly divided into a training cohort and a validation cohort at a ratio of 7:3. The constructed Symptomatic Patients Colorectal Screening (SPCS) score showed higher diagnostic efficacy and sensitivity than several previous scoring systems. Using the SPCS score, the patients were divided into a low-risk group (-2 to 3 points) and a high-risk group (4-10 points) for CRN. Additionally, the detection rate of CRN in the training and validation cohorts of the high-risk group were 41.7% and 37.0%, respectively. The SPCS score detected 79.3% (188/237) of CRN and 87.5% (42/48) of advanced CRN in the high-risk group, which reduced the workload of colonoscopy to 45.9% (466/1016).

CONCLUSION

An effective CRN risk scoring system was established and validated for symptomatic patients, which accurately classified individuals into low-risk and high-risk groups for CRN and might be used to optimize colonoscopic resource allocation.

Noninvasive predictive models based on lifestyle analysis and risk factors for early-onset colorectal cancer

BACKGROUND

Colorectal cancer (CRC) incidence has increased among patients aged <50 years. Exploring high-risk factors and screening high-risk populations may help lower early-onset CRC (EO-CRC) incidence. We developed noninvasive predictive models for EO-CRC and investigated its risk factors.

METHODS

This retrospective multicenter study collected information on 1756 patients (811 patients with EO-CRC and 945 healthy controls) from two medical centers in China. Sociodemographic features, clinical symptoms, medical and family history, lifestyle, and dietary factors were measured. Patients from one cohort were randomly assigned (8:2) to two groups for model establishment and internal validation, and another independent cohort was used for external validation. Multivariable logistic regression, random forest, and eXtreme Gradient Boosting (XGBoost) were performed to establish noninvasive predictive models for EO-CRC. Some variables in the model influenced EO-CRC occurrence and were further analyzed. Multivariable logistic regression analysis yielded adjusted odd ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

All three models showed good performance, with areas under the receiver operator characteristic curves (AUCs) of 0.82, 0.84, and 0.82 in the internal and 0.78, 0.79, and 0.78 in the external validation cohorts, respectively. Consumption of sweet (OR 2.70, 95% CI 1.89-3.86, P < 0.001) and fried (OR 2.16, 95% CI 1.29-3.62, P < 0.001) foods ≥3 times per week was significantly associated with EO-CRC occurrence.

CONCLUSION

We established noninvasive predictive models for EO-CRC and identified multiple nongenetic risk factors, especially sweet and fried foods. The model has good performance and can help predict the occurrence of EO-CRC in the Chinese population.

Comparing efficacy and factors of postoperative bleeding in endoscopic mucosal resection vs coagulation for intestinal polyps

This study aimed to assess the effectiveness of Endoscopic Mucosal Resection (EMR) and Argon Plasma Coagulation (APC) as therapeutic approaches for intestinal polyps in patients, and to examine the factors associated with postoperative bleeding. This study included 132 patients diagnosed with colorectal polyps (188 polyps) who underwent endoscopic surgery at our hospital between January 2022 and December 2022. Based on the surgical method employed, the patients were divided into 2 groups: EMR (68 cases, 97 polyps) and APC (64 cases, 91 polyps). Comparative analyses were conducted to assess the clinical efficacy, surgery-related indicators, and quality of life the 2 groups. Furthermore, an investigation was carried out to identify the factors associated with postoperative bleeding. The analysis revealed no statistically significant difference in the cure rate of flat and superficial raised polyps between the EMR group and the APC (P > .05). However, it was found that the EMR group exhibited a significantly higher cure rate for subpedunculated and raised-pedunculated polyps compared to the APC group (P < .05). The results of logistics analysis showed that patients with hypertension (OR = 2.876, 95% CI: 1.119-7.393), patients with diabetes (OR = 5.278, 95% CI: 1.388-20.064), patients with hyperlipidemia (OR = 2.594, 95% CI: 1.054-6.380), the polyps of right hemicolon (OR = 2.743, 95% CI: 1.003-7.504), rectal polyps (OR = 5.143, 95% CI: 1.728-7.504), pedunculated polyps (OR = 4.758, 95% CI: 1.322-17.129), adenomatous polyps (OR = 3.152, 95% CI: 1.018-9.757) were independent risk factors for postoperative bleeding in patients with colorectal polyps (P < .05). The findings suggest that for subpedunculated and pedunculated-raised polyps, EMR can be a suitable treatment approach. On the other hand, flat and superficial-raised polyps can be effectively managed with either EMR or APC. The presence of hypertension, diabetes, hyperlipidemia, polyps of the right hemicolon, rectal polyps, pedunculated polyps, and adenomatous polyps has been established as independent risk factors for postoperative bleeding in patients with colorectal polyps.

Detection of Human cytomegalovirus UL55 Gene and IE/E Protein Expression in Colorectal Cancer Patients in Egypt

BACKGROUND

A possible relation between Human cytomegalovirus (HCMV) and colorectal cancer (CRC) has been widely explored with an unclear role yet speculated.

AIM

The study aimed at detecting HCMV UL55 gene, immediate early and early (IE/E) proteins in colorectal tumor tissues and adjacent non neoplastic tissues (ANNT). Also, it aimed to correlate HCMV presence with CRC clinicopathological features.

SUBJECTS AND METHODS

A prospective study of 50 HCMV seropositive patients with resectable CRC were enrolled in the study. Demographic, clinical, and radiological findings were recorded. Pathological assessment was done. Paired CRC tumorous and ANNT were examined for HCMV UL55 by PCR and for IE/ E proteins by immunohistochemistry (IHC).

RESULTS

70% of CRC patients enrolled were females and 36% were elderly (> 60y). Adenocarcinoma was the prevalent histopathological type (92%) with Grade 2, higher stages, and nodal involvement accounting for (64%, 64% and 56%) respectively. HCMV detection was significantly higher in tumoral tissue versus ANNT by PCR and IHC (P < 0.001, P < 0.008) respectively. Moderate agreement was found between the two techniques (κ = 0.572, P < 0.001). Univariate analysis identified HCMV presence to be significantly higher in elderly patients, in tumors with higher stage and with nodal involvement (P = 0.041, P = 0.008, P = 0.018 respectively). In multivariate analysis, the latter two retained significance (P = 0.010, P = 0.008).

CONCLUSION

CRC tumor tissues are more infected by HCMV than ANNT. A significant association of HCMV presence with a higher CRC tumor stage and nodal involvement in an age-dependent manner was detected. HCMV oncomodulatory and a disease progression role is suspected.

Colorectal cancer and advanced adenoma incidence during post-polypectomy surveillance: a national cohort study in the English Bowel Cancer Screening Programme

BACKGROUND

Improved colonoscopy quality has led to debate about whether all post-polypectomy surveillance is justified. We evaluated surveillance within the English Bowel Cancer Screening Programme (BCSP) to determine the yield of surveillance and identify predictive factors for surveillance outcome.

METHODS

We performed a retrospective cohort study of individuals undergoing post-polypectomy surveillance between July 2006 and January 2017. BCSP records were linked to the National Cancer Registration Database to identify interval-type post-colonoscopy colorectal cancers (CRCs). Advanced adenoma and CRC at surveillance were documented. CRC incidence was compared with the general population using standardized incidence ratios (SIRs). Predictors of advanced adenomas at first surveillance (S1), and CRC during follow-up, were identified.

RESULTS

44 151 individuals (23 078 intermediate risk; 21 073 high risk) underwent 64 544 surveillance episodes. Advanced adenoma and CRC yields were, respectively, 10.0 % and 0.5 % at S1, 8.5 % and 0.4 % at S2, and 10.8 % and 0.4 % at S3. S1 yield was lowest in those with one index adenoma ≥ 10 mm (advanced adenoma 6.1 %; CRC 0.3 %). The SIR was 0.76 (95 %CI 0.66-0.88), accounted for by the intermediate risk group (intermediate risk SIR 0.61, 95 %CI 0.49-0.75; high risk SIR 0.95, 95 %CI 0.79-1.15). Adenoma multiplicity, presence of a large nonpedunculated adenoma, and greater villous component were associated with advanced adenoma at S1. Older age and multiplicity were significantly associated with CRC risk.

CONCLUSION

This large, national analysis found low levels of CRC in those undergoing surveillance and low advanced adenoma yield in most subgroups. Less intensive surveillance in some subgroups is warranted, and surveillance may be avoided in those with a single large adenoma.

Methylmalonic acid promotes colorectal cancer progression via activation of Wnt/β-catenin pathway mediated epithelial-mesenchymal transition

BACKGROUND

It has been manifested in several studies that age-related metabolic reprogramming is associated with tumor progression, in particular, colorectal cancer (CRC). Here we investigated the role of upregulated metabolites of the aged serum, including methylmalonic acid (MMA), phosphoenolpyruvate (PEP), and quinolinate (QA), in CRC.

METHODS

Functional assays including CCK-8, EdU, colony formation and transwell experiments were used to ascertain which upregulated metabolite of elderly serum was related to tumor progression. RNA-seq analysis was conducted to explore the potential mechanisms of MMA-induced CRC progression. Subcutaneous tumorigenesis and metastatic tumor models were constructed to verify the function of MMA in vivo.

RESULTS

Among three consistently increased metabolites of the aged sera, MMA was responsible for tumorigenesis and metastasis in CRC, according to functional assays. The promotion of Epithelial-mesenchymal transition (EMT) was observed in CRC cells treated with MMA, on the basis of protein expression of EMT markers. Moreover, combined with transcriptome sequencing, Wnt/β-catenin signaling pathway was activated in CRC cells treated with MMA, which was verified by western blot and qPCR experiments. Furthermore, animal assays demonstrated the pro-proliferation and promotion of metastasis role of MMA in vivo.

CONCLUSION

We have identified that age-dependent upregulation of MMA in serum promoted the progression of CRC via Wnt/β-catenin signaling pathway mediated EMT. These collective findings provide valuable insights into the vital role of age-related metabolic reprogramming in CRC progression and propose a potential therapeutic target for elderly CRC.

Prevalence of clinical signs, symptoms and comorbidities at diagnosis of acromegaly: a systematic review in accordance with PRISMA guidelines

OBJECTIVE

Diagnostic delay is high in acromegaly and leads to increased morbidity and mortality. The aim of this study is to systematically assess the most prevalent clinical signs, symptoms and comorbidities of acromegaly at time of diagnosis.

DESIGN

A literature search (in PubMed, Embase and Web of Science) was performed on November 18, 2021, in collaboration with a medical information specialist.

METHODS

Prevalence data on (presenting) clinical signs, symptoms and comorbidities at time of diagnosis were extracted and synthesized as weighted mean prevalence. The risk of bias was assessed for each included study using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data.

RESULTS

Risk of bias and heterogeneity was high in the 124 included articles. Clinical signs and symptoms with the highest weighted mean prevalence were: acral enlargement (90%), facial features (65%), oral changes (62%), headache (59%), fatigue/tiredness (53%; including daytime sleepiness: 48%), hyperhidrosis (47%), snoring (46%), skin changes (including oily skin: 37% and thicker skin: 35%), weight gain (36%) and arthralgia (34%). Concerning comorbidities, acromegaly patients more frequently had hypertension, left ventricle hypertrophy, dia/systolic dysfunction, cardiac arrhythmias, (pre)diabetes, dyslipidemia and intestinal polyps- and malignancy than age- and sex matched controls. Noteworthy, cardiovascular comorbidity was lower in more recent studies. Features that most often led to diagnosis of acromegaly were typical physical changes (acral enlargement, facial changes and prognatism), local tumor effects (headache and visual defect), diabetes, thyroid cancer and menstrual disorders.

CONCLUSION

Acromegaly manifests itself with typical physical changes but also leads to a wide variety of common comorbidities, emphasizing that recognition of a combination of these features is key to establishing the diagnosis.

Analysis of the relationship between the gut microbiota enterotypes and colorectal adenoma

Introduction

The essence of enterotypes is to stratify the entire human gut microbiota, and dysregulation of gut microbiota is closely related to the development of colorectal adenoma. Enterotypes may therefore be a useful target for the prevention of colorectal adenoma. However, the relationship between gut microbiota and colorectal adenoma has not been fully elucidated. In this study, we aimed to analyze the differences in gut microbiome composition between adenoma and control populations.

Methods

We recruited 31 patients with colorectal adenoma and 71 non-adenoma controls. Patient demographics, risk factors, fecal samples from each subject were collected and metagenomic sequencing was performed. LEfSe analysis was used to reveal differences in intestinal microbiome composition. Multiple logistic regression analysis was used to determine the association between enterotypes and colorectal adenoma.

Results

The results showed that Prevotella enterotype (enterotype 4) is only present in adenoma group. Logistic regression analysis showed that Prevotella enterotype was an independent risk factor for colorectal adenoma.

Discussion

The Prevotella enterotype may increase the occurrence of colorectal adenoma through inflammatory association and interference with glucose and lipid metabolism in human body. In conclusion, the differences we observed between different enterotypes add a new potential factor to the development of colorectal adenoma.

The Use of a Non-Invasive Biomarker for Colorectal Cancer Screening: A Comparative Cost-Effectiveness Modeling Study

This study aimed to examine the cost-effectiveness of fecal biomarker M3 panel compared to fecal immunochemical test (FIT) and colonoscopy in an Asian population. In a hypothetical population of 100,000 persons aged 50 years who received FIT yearly, M3 biomarker yearly, or colonoscopy every 10 years until the age of 75 years. Participants with positive FOBT or a result of "high risk" identified using the M3 biomarker are offered colonoscopy. We assumed surveillance colonoscopy is repeated every 3 years, and examined the treatment cost. A comparison of various outcome measures was conducted using Markov modelling. The incremental cost-effectiveness ratio (ICER) of FIT, M3 biomarker, and colonoscopy was USD108,176, USD133,485 and USD159,596, respectively. Comparing with FIT, the use of M3 biomarker could lead to significantly smaller total loss of cancer-related life-years (2783 vs. 5279); a higher number of CRC cases prevented (1622 vs. 146), a higher proportion of CRC cases prevented (50.2% vs. 4.5%), more life-years saved (2852 vs. 339), and cheaper total costs per life-year saved (USD212,553 vs. 773,894). The total costs per life-year saved is more affordable than that achieved by colonoscopy as a primary screening tool (USD212,553 vs. USD236,909). The findings show that M3 biomarkers may be more cost-effective than colonoscopy.

Multiple Negative Fecal Immunochemical Tests Reduce Risk of Advanced Neoplasia in a Colonoscopy Surveillance Program

BACKGROUND & AIMS

In above-average-risk individuals undergoing colonoscopy-based surveillance for colorectal cancer (CRC), screening with fecal immunochemical tests (FIT) between colonoscopies might facilitate personalization of surveillance intervals. Because a negative FIT is associated with a reduced risk for CRC, we examined the relationship between number of rounds of negative FIT and risk for advanced neoplasia in individuals undergoing surveillance colonoscopy.

METHODS

We conducted a retrospective cohort study on 4021 surveillance intervals in 3369 individuals (50-74 years), who had completed a 2-sample FIT between colonoscopies, from 1 to 4 rounds at 1-2 yearly intervals, each with a negative result (<20 μg hemoglobin/g feces). Incidence of advanced neoplasia (CRC or advanced adenoma) was determined at the follow-up colonoscopy. Competing-risk regression was used to assess the association between multiple negative FIT results and the risk of advanced neoplasia within 2 years.

RESULTS

The incidence of advanced neoplasia in the cohort was 9.9% and decreased with increasing numbers of rounds of negative FIT results: 11.1% after 1 negative FIT to 5.7% after 4 negative FIT. The risk of advanced neoplasia was significantly lower in participants with 3 (subdistribution hazard ratio, 0.50; 95% confidence interval, 0.24-0.97) and 4 (subdistribution hazard ratio, 0.33; 95% confidence interval, 0.15-0.73) rounds of negative FIT compared with only 1 negative FIT.

CONCLUSIONS

There was a low risk of advanced neoplasia after multiple rounds of negative FIT in above-average-risk people undergoing surveillance with no neoplasia or nonadvanced adenoma at prior colonoscopy. This supports the use of interval FIT to personalize surveillance by lengthening colonoscopy intervals following multiple negative FIT results.

Systematic Review: Contribution of the Gut Microbiome to the Volatile Metabolic Fingerprint of Colorectal Neoplasia

Colorectal cancer (CRC) has been associated with changes in volatile metabolic profiles in several human biological matrices. This enables its non-invasive detection, but the origin of these volatile organic compounds (VOCs) and their relation to the gut microbiome are not yet fully understood. This systematic review provides an overview of the current understanding of this topic. A systematic search using PubMed, Embase, Medline, Cochrane Library, and the Web of Science according to PRISMA guidelines resulted in seventy-one included studies. In addition, a systematic search was conducted that identified five systematic reviews from which CRC-associated gut microbiota data were extracted. The included studies analyzed VOCs in feces, urine, breath, blood, tissue, and saliva. Eight studies performed microbiota analysis in addition to VOC analysis. The most frequently reported dysregulations over all matrices included short-chain fatty acids, amino acids, proteolytic fermentation products, and products related to the tricarboxylic acid cycle and Warburg metabolism. Many of these dysregulations could be related to the shifts in CRC-associated microbiota, and thus the gut microbiota presumably contributes to the metabolic fingerprint of VOC in CRC. Future research involving VOCs analysis should include simultaneous gut microbiota analysis.

Serum Chloride and Admission Status Are Potential Prognostic Markers of High-Risk Polyps: A Prospective Characterization of Colorectal Polyps in a Tertiary Hospital in Saudi Arabia

Background: Colorectal cancer (CRC) is the most common cancer in men in Saudi Arabia. Other than age and family history, clinical and laboratory prognostic surrogates that may aid in streamlining and prioritization of screening colonoscopies are scarce. Through the examination of the local prevalence of advanced and malignant colorectal polyps, we hypothesized that the presence of certain clinical or laboratory parameters may signify an association with having high-risk polyps.

Methods: A prospective study over a period of one year starting on January 21, 2018 and involving all adult patients undergoing colonoscopy at King Saud Medical City, Riyadh. Of the total 1,104 recruited patients, 717 were included. The patients were sub-grouped based on the presence or absence of polyps. Patients with polyps were further sub-grouped into high-risk or low-risk polyps. Comparisons between groups were performed using univariate, relative risks (RRs), and multivariate analyses.

Results: Our polyp detection rate was 34.7% and our adenoma detection rate was 21.3%. The prevalence of advanced adenoma was 15.2% and the prevalence of malignant polyps was 6.7%. Several prognostic markers were associated with high-risk polyps such as advanced age (RR = 1.35, 95% confidence interval [CI]: 1.03 to 1.78), male gender (RR = 1.18, 95% CI: 1.06 to 1.31), inpatient status (RR = 1.46, 95% CI: 1.04 to 2.21), and low serum chloride (RR = 1.89, 95% CI: 1.05 to 2.37). With multivariate analysis, the hazard ratios for inpatient status and hypochloremia were 1.67 (95% CI: 1.034 to 2.612) and 1.12 (95% CI: 1.011 to 1.265), respectively.

Conclusion: We report the prevalence of malignant colorectal polyps in Saudi Arabia which was not reported before. Two unique prognostic markers for high-risk polyps were identified, namely, inpatient status and hypochloremia.

Screening for Colorectal Cancer

Colorectal cancer (CRC) is the second-leading cause of cancer death in the United States. Screening reduces CRC incidence and mortality. 2021 US Preventive Service Task Force (USPSTF) guidelines and available evidence support routine screening from ages 45 to 75, and individualized consideration of screening ages 76 to 85. USPSTF guidelines recommend annual guaiac fecal occult blood testing, annual fecal immunochemical testing (FIT), annual to every 3-year multitarget stool DNA-FIT, every 5-year sigmoidoscopy, every 10-year sigmoidoscopy with annual FIT, every 5-year computed tomographic colonography, and every 10-year colonoscopy as options for screening. The "best test is the one that gets done."

Colon Cancer: From Epidemiology to Prevention

Colorectal cancer (CRC) is one of the most prevalent cancers affecting humans, with a complex genetic and environmental aetiology. Unlike cancers with known environmental, heritable, or sex-linked causes, sporadic CRC is hard to foresee and has no molecular biomarkers of risk in clinical use. One in twenty CRC cases presents with an established heritable component. The remaining cases are sporadic and associated with partially obscure genetic, epigenetic, regenerative, microbiological, dietary, and lifestyle factors. To tackle this complexity, we should improve the practice of colonoscopy, which is recommended uniformly beyond a certain age, to include an assessment of biomarkers indicative of individual CRC risk. Ideally, such biomarkers will be causal to the disease and potentially modifiable upon dietary or therapeutic interventions. Multi-omics analysis, including transcriptional, epigenetic as well as metagenomic, and metabolomic profiles, are urgently required to provide data for risk analyses. The aim of this article is to provide a perspective on the multifactorial derailment of homeostasis leading to the initiation of CRC, which may be explored via multi-omics and Gut-on-Chip analysis to identify much-needed predictive biomarkers.

Expression of Autophagic and Inflammatory Markers in Normal Mucosa of Individuals with Colorectal Adenomas: A Cross Sectional Study among Italian Outpatients Undergoing Colonoscopy

Colorectal cancer (CRC) ranks among the three most common cancers in terms of both cancer incidence and cancer-related deaths in Western industrialized countries. Lifetime risk of colorectal cancer may reach 6% of the population living in developed countries. In the current era of personalized medicine, CRC is no longer considered as a single entity. In more recent years many studies have described the distinct differences in epidemiology, pathogenesis, genetic and epigenetic alterations, molecular pathways and outcome depending on the anatomical site. The aim of our study is to assess in a multidimensional model the association between metabolic status and inflammatory and autophagic changes in the normal colorectal mucosa classified as right-sided, left-sided and rectum, and the presence of adenomas. One hundred and sixteen patients undergoing colonoscopy were recruited and underwent a complete serum lipid profile, immunofluorescence analysis of colonic biopsies for MAPLC3 and myeloperoxidase expression, matched with clinical and anthropometric characteristics. Presence of adenomas correlated with cholesterol (total and LDL) levels, IL-6 levels, and MAPLC3 tissue expression, especially in the right colon. In conclusion, serum IL-6 amount and autophagic markers could be good predictors of the presence of colorectal adenomas.

Cause, Epidemiology, and Histology of Polyps and Pathways to Colorectal Cancer

Colorectal cancer is the second leading cause of cancer-associated mortality, with a lifetime risk of approximately 4% to 5%. Colorectal cancer develops from the sequential acquisition of defined genetic mutations in the colonic epithelium. Tumorigenesis from normal tissue to cancer occurs largely through 3 pathways: the chromosomal instability pathway, the microsatellite instability pathway, and the sessile serrated pathway. Colorectal cancer incidence and mortality have decreased by approximately 35% since the beginning of screening programs in the 1990s, although other factors such as use of aspirin for coronary disease prevention and decreased smoking rates may also be important. In this review, we discuss the etiology, epidemiology, and histology of colorectal polyps and cancer.

Prevalence of Pulmonary Embolism and Deep Venous Thromboembolism in Patients With Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) increases the risk of pulmonary embolism (PE) and deep venous thrombosis (DVT). AECOPD combined with PE and DVT poses challenges for treatment and management. This necessitates prevention and management to estimate the overall prevalence of PE and DVT among patients with AECOPD and to identify the risk factors.

Methods

We searched the PubMed, Embase, and Cochrane Library databases from their inception to January 9, 2021 and extracted the data from the included studies. The risk of bias was assessed for each study. We separately calculated the prevalence of PE and DVT in patients with AECOPD. Subgroup analysis and meta-regression analyses were performed to determine the sources of heterogeneity. Furthermore, we assessed the publication bias.

Results

The meta-analysis included 20 studies involving 5,854 people. The overall prevalence of PE and DVT among patients with AECOPD was 11% (95% CI: 0.06–0.17) and 9% (95% CI: 0.06–0.12), respectively. Subgroup analysis demonstrated that the prevalence of PE among patients with AECOPD was 12, 2, 7, and 16% in the European, South-East Asia, Western Pacific, and Eastern Mediterranean regions, respectively, and the DVT was 10, 9, 9, and 4%, respectively. The prevalence of PE among patients with AECOPD aged ≥ 70 and <70 years old was 6 and 15%, respectively, and the DVT was 8 and 9%, respectively. The prevalence of PE among patients with AECOPD diagnosed within 48 h and other times (beyond 48 h or not mentioned) was 16 and 6%, respectively, and DVT was 10 and 7%, respectively.

Conclusion

The pooled prevalence of PE and DVT among patients with AECOPD was insignificantly different between the different age groups and the WHO regions. However, the early diagnosis was associated with a higher prevalence of PE. Clinicians and the public need to further improve the awareness of prevention and management for PE and DVT among patients with AECOPD.

Systematic Review Registration

PROSPERO, identifier CRD42021260827.

ZnO nanoparticles promote the malignant transformation of colorectal epithelial cells in APCmin/+ mice

As the use of zinc oxide nanoparticles (ZnO NPs) in everyday products grows, so does concern about health risks. However, no findings on the gastrointestinal toxicity of ZnO NPs have been published. We investigated the possible malignant transformation of ZnO NPs in the mice's colonic tissues using the APC^min/+ mouse model with a premalignant lesion in intestinal epithelial cells. Higher doses and long-term oral exposure to ZnO NPs were found to mildly promote colonic inflammation in WT mice, while they moderately or strongly exacerbated the severity of chronic inflammation and tumorigenesis in APC^min/+ mice with intestinal adenomatous polyposis. The ZnO NPs-induced inflammation and tumorigenesis in colonic epithelial cells was linked to the activation of CXCR2/NF-κB/STAT3/ERK and AKT pathways. Analysis of the ZnO NPs-exacerbated intestinal adenomatous polyposis in APC^min/+ mice revealed that ZnO NPs could activate the APC-driven Wnt/β-catenin signaling pathway, exacerbating intestinal tumorigenesis. In fact, ZnO NPs have been shown to increase intestinal inflammation and tumorigenesis in APC^min/+ mice by releasing free Zn²⁺. In WT mice, a low dose of ZnO NPs (26 mg/kg/day) did not cause intestinal inflammation. In conclusion, higher doses and prolonged exposure to ZnO NPs promote the malignant transformation of precancerous epithelial cells.

Early-Age Onset Colorectal Neoplasia in Average-Risk Individuals Undergoing Screening Colonoscopy: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Incidence and mortality associated with early-age onset colorectal cancer (EAO-CRC) is increasing, prompting professional society recommendations to lower the screening age in average-risk individuals. The yield of screening individuals younger than 50 years is not known.

METHODS

A systematic review of 3 databases from inception through July 2020 was performed in all languages that reported colonoscopy findings in average-risk individuals younger than 50 years. The primary outcomes were EAO colorectal neoplasia (CRN) and advanced colorectal neoplasia (aCRN) prevalence. Subgroup analyses were performed based on sex, geographic location, time period, and age, including comparison with those aged 50-59 years. Generalized linear mixed model with random intercept logistic regression and fixed subgroup effects were performed.

RESULTS

Of 10,123 unique articles, 17 studies published between 2002 and 2020, including 51,811 average-risk individuals from 4 continents, were included. The pooled rate of EAO-CRN was 13.7% (95% confidence interval [CI], 0.112%-0.168%) and EAO-aCRN was 2.2% (95% CI, 0.016%-0.031%). Prevalence of CRC was 0.05% (95% CI, 0.00029%-0.0008%). Rates of EAO-CRN were higher in men compared with women (relative risk, 1.71%; 95% CI, 1.49%-1.98%), and highest in the United States (15.6%; 95% CI, 12.2%-19.7%) compared with Europe (14.9%; 95% CI, 6.9%-29.3%), East Asia (13.4%; 95% CI, 10.3%-17.2%), and the Middle East (9.8%; 95% CI, 7.8%-12.2%) (P = .04) The rate of EAO-CRN in age groups 45-49 years and 50-59 years was 17.8% (95% CI, 14.5%-21.6%) and 24.8% (95% CI, 19.5%-30.8%), respectively (P = .04). The rate of EAO-aCRN in age group 45-49 years was 3.6% (95% CI, 1.9%-6.7%) and 4.2% (95% CI, 3.2%-5.7%), respectively (P = .69).

CONCLUSIONS

The rate of aCRN in individuals aged 45-49 years was similar to the rate observed in individual aged 50-59 years, suggesting that expanding screening to this population could yield a similar impact on colorectal cancer risk reduction.

Ability of known colorectal cancer susceptibility SNPs to predict colorectal cancer risk: A cohort study within the UK Biobank

Colorectal cancer risk stratification is crucial to improve screening and risk-reducing recommendations, and consequently do better than a one-size-fits-all screening regimen. Current screening guidelines in the UK, USA and Australia focus solely on family history and age for risk prediction, even though the vast majority of the population do not have any family history. We investigated adding a polygenic risk score based on 45 single-nucleotide polymorphisms to a family history model (combined model) to quantify how it improves the stratification and discriminatory performance of 10-year risk and full lifetime risk using a prospective population-based cohort within the UK Biobank. For both 10-year and full lifetime risk, the combined model had a wider risk distribution compared with family history alone, resulting in improved risk stratification of nearly 2-fold between the top and bottom risk quintiles of the full lifetime risk model. Importantly, the combined model can identify people (n = 72,019) who do not have family history of colorectal cancer but have a predicted risk that is equivalent to having at least one affected first-degree relative (n = 44,950). We also confirmed previous findings by showing that the combined full lifetime risk model significantly improves discriminatory accuracy compared with a simple family history model 0.673 (95% CI 0.664–0.682) versus 0.666 (95% CI 0.657–0.675), p = 0.0065. Therefore, a combined polygenic risk score and first-degree family history model could be used to improve risk stratified population screening programs.

Computer-Aided Diagnosis of Diminutive Colorectal Polyps in Endoscopic Images: Systematic Review and Meta-analysis of Diagnostic Test Accuracy

Background

Most colorectal polyps are diminutive and benign, especially those in the rectosigmoid colon, and the resection of these polyps is not cost-effective. Advancements in image-enhanced endoscopy have improved the optical prediction of colorectal polyp histology. However, subjective interpretability and inter- and intraobserver variability prohibits widespread implementation. The number of studies on computer-aided diagnosis (CAD) is increasing; however, their small sample sizes limit statistical significance.

Objective

This review aims to evaluate the diagnostic test accuracy of CAD models in predicting the histology of diminutive colorectal polyps by using endoscopic images.

Methods

Core databases were searched for studies that were based on endoscopic imaging, used CAD models for the histologic diagnosis of diminutive colorectal polyps, and presented data on diagnostic performance. A systematic review and diagnostic test accuracy meta-analysis were performed.

Results

Overall, 13 studies were included. The pooled area under the curve, sensitivity, specificity, and diagnostic odds ratio of CAD models for the diagnosis of diminutive colorectal polyps (adenomatous or neoplastic vs nonadenomatous or nonneoplastic) were 0.96 (95% CI 0.93-0.97), 0.93 (95% CI 0.91-0.95), 0.87 (95% CI 0.76-0.93), and 87 (95% CI 38-201), respectively. The meta-regression analysis showed no heterogeneity, and no publication bias was detected. Subgroup analyses showed robust results. The negative predictive value of CAD models for the diagnosis of adenomatous polyps in the rectosigmoid colon was 0.96 (95% CI 0.95-0.97), and this value exceeded the threshold of the diagnosis and leave strategy.

Conclusions

CAD models show potential for the optical histological diagnosis of diminutive colorectal polyps via the use of endoscopic images.

Trial Registration

PROSPERO CRD42021232189; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=232189

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.

Performance of the faecal immunochemical test for the detection of colorectal neoplasms and the role of proton pump inhibitors in their diagnostic accuracy

AIM

The faecal immunochemical test (FIT) is currently utilized in both symptomatic and screening populations, but little is known about factors that affect its performance. For example, proton pump inhibitor (PPI) therapy has been purported to increase false negative rates. This has significant implications given the extent of PPI prescriptions. The aim of this work was to evaluate the performance of the FIT for the detection of colorectal neoplasms and the impact of PPI therapy on its diagnostic accuracy.

METHOD

Symptomatic patients referred on the suspected cancer pathway and those on polyp surveillance between 2015 and 2019 were approached to participate. Estimates of the accuracy of FIT at different cut-off levels in diagnosing colorectal neoplasms were made. Logistic regression was used to assess the effect of PPIs on the FIT results.

RESULTS

A total of 667 participants were eligible for the final analysis. At a cut-off of 10 μg/g faeces, the overall sensitivity and specificity of FIT for the detection of colorectal cancer (CRC) was 0.85 (95% CI 0.71-0.94) and 0.81 (95% CI 0.78-0.84), respectively. For the detection of advanced neoplasia, the sensitivity was 0.70 (95% CI 0.58-0.79) and the specificity was 0.83 (95% CI 0.80-0.86). At higher thresholds, the sensitivity steadily declined whilst specificity increased. PPI therapy did not have a significant effect on performance of the FIT.

CONCLUSION

FIT is a good rule-out test for the detection of CRC and advanced neoplasia at lower thresholds. PPI therapy does not appear to have an effect on its diagnostic performance.

The dysbiosis signature of Fusobacterium nucleatum in colorectal cancer-cause or consequences? A systematic review

Colorectal cancer (CRC) is the third most common cause of cancer globally and the fourth attributable cause of mortality and morbidity due to cancer. An emerging factor contributing to CRC is the gut microbiota and the cellular changes associated with it. Further insights on this may help in the prevention, diagnosis and new therapeutic approaches to colorectal cancer. In most cases of CRC, genetic factors appear to contribute less to its aetiology than environmental and epigenetic factors; therefore, it may be important to investigate these environmental factors, their effects, and the mechanisms that may contribute to this cancer. The gut microbiota has recently been highlighted as a potential risk factor that may affect the structural components of the tumor microenvironment, as well as free radical and enzymatic metabolites directly, or indirectly. Many studies have reported changes in the gut microbiota of patients with colorectal cancer. What is controversial is whether the cancer is the cause or consequence of the change in the microbiota. There is strong evidence supporting both possibilities. The presence of Fusobacterium nucleatum in human colorectal specimens has been demonstrated by RNA-sequencing. F. nucleatum has been shown to express high levels of virulence factors such as FadA, Fap2 and MORN2 proteins. Our review of the published data suggest that F. nucleatum may be a prognostic biomarker of CRC risk, and hence raises the potential of antibiotic treatment of F. nucleatum for the prevention of CRC.

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.

Rate of detection of serrated lesions at colonoscopy in an average-risk population: a meta-analysis of 129,001 individuals

Background and study aims  Serrated lesions are precursors of approximately one-third of colorectal cancers (CRCs). Information on their detection rate was lacking as an important reference for CRC screening. This study was a systematic review and meta-analysis to determine the overall detection rate for serrated lesions and their subtypes in average-risk populations undergoing CRC screening with colonoscopy. Patient and methods  MEDLINE and Embase were searched to identify population-based studies that reported the detection rate for serrated lesions. Studies on average-risk populations using colonoscopy as a screening tool were included. Metaprop was applied to model within-study variability by binomial distribution, and Freeman-Tukey Double Arcsine Transformation was adopted to stabilise the variances. The detection rate was presented in proportions using random-effects models. Results  In total, 17 studies involving 129,001 average-risk individuals were included. The overall detection rates for serrated lesions (19.0 %, 95 % CI = 15.3 %-23.0 %), sessile serrated polyps (2.5 %, 95 % CI = 1.5 %-3.8 %), and traditional serrated adenomas (0.3 %, 95 % CI = 0.1 %-0.8 %) were estimated. Subgroup analysis indicated a higher detection rate for serrated lesions among males (22.0 %) than females (14.0 %), and Caucasians (25.9 %) than Asians (14.6 %). The detection rate for sessile serrated polyps was also higher among Caucasians (2.9 %) than Asians (0.7 %). Conclusions  This study determined the overall detection rate for serrated lesions and their different subtypes. The pooled detection rate estimates can be used as a reference for establishing CRC screening programs. Future studies may evaluate the independent factors associated with the presence of serrated lesions during colonoscopy to enhance their rate of detection.

Comparison of Risk of Metachronous Advanced Colorectal Neoplasia in Patients with Sporadic Adenomas Aged < 50 Versus ≥ 50 years: A Systematic Review and Meta-Analysis

No specific recommendations are available for the surveillance of young patients aged <50 years undergoing polypectomy. We aimed to compare the risk of metachronous advanced colorectal neoplasia (ACRN) between patients aged ≥50 years and those aged <50 years who underwent polypectomy. Studies published between January 1980 and June 2020 that examined the risk of metachronous ACRN were searched. We performed a meta-analysis for the metachronous ACRN risk in patients with sporadic colorectal adenomas according to the age groups (≥50 vs. <50 years). Eight individual studies were included in the meta-analysis. The risk of metachronous ACRN was higher in patients aged ≥50 years than in those aged <50 years without significant heterogeneity (odds ratio (OR) (95% CI): 1.62 (1.34–1.96), I² = 14%). The impact of the age group on the risk of metachronous ACRN was identified in both the low-risk (LRA) and high-risk (HRA) adenoma groups (≥50 vs. <50 years: LRA, OR 1.88 (95% CI 1.30–2.70); HRA, OR 1.50 [95% CI 1.13–2.00]). In conclusion, patients aged <50 years had a lower risk of metachronous ACRN than older patients. Young patients with sporadic adenomas do not require more intensive surveillance; rather, the surveillance interval may be extended in these patients.

Exosomal Long Non-coding RNA HOTTIP Increases Resistance of Colorectal Cancer Cells to Mitomycin via Impairing MiR-214-Mediated Degradation of KPNA3

It has been reported that long non-coding RNA HOXA distal transcript antisense RNA (lncRNA HOTTIP) functions as a tumor promoter in colorectal cancer (CRC). Hence, we paid attention to exploring whether exosomes could carry lncRNA HOTTIP to affect the mitomycin resistance in CRC and to identify the underlying mechanisms. High expression of HOTTIP was detected in mitomycin-resistant CRC cells. Inhibition of HOTTIP reduced the mitomycin resistance. In the co-culture system of mitomycin-resistant cells or their derived exosomes with CRC cells, the HOTTIP was found to be transferred into the parental cells via extracellular vesicles (EVs) secreted from mitomycin-resistant cells and to contribute to the mitomycin resistance. Based on the bioinformatics databases, possible interaction network of HOTTIP, microRNA-214 (miR-214) and Karyopherin subunit alpha 3 (KPNA3) in CRC was predicted, which was further analyzed by dual-luciferase reporter, RNA binding protein immunoprecipitation and RNA pull-down assays. As HOTTIP down-regulated miR-214 to elevate the KPNA3 expression, HOTTIP enhanced the mitomycin resistance through impairing miR-214-dependent inhibition of KPNA3. Finally, HOTTIP was suggested as an independent factor predicting mitomycin response in patients with CRC. Those data together confirmed the promotive effects of EV-carried HOTTIP on the mitomycin resistance, while targeting HOTTIP might be a promising strategy overcoming drug resistance in CRC.

Variation in changes in the incidence of colorectal cancer by age and association with screening uptake: an observational study

OBJECTIVES

In developed countries, the incidence of colorectal cancer (CRC) has declined in the over 50 years age group but increased in younger people. We studied CRC incidence by age and the influence of screening uptake.

DESIGN

Age-standardised and sex-standardised incidences for CRC from 1997 to 2017 were obtained from the Scottish Cancer Registry (SCR). In addition, linkage between the Scottish Bowel Screening Database and the SCR allowed investigation of any association between screening participation and CRC incidence.

SETTING

Scotland and the Scottish Bowel Screening Programme, in which guaiac faecal occult blood test screening was piloted from March 2000 and fully rolled by December 2009.

PARTICIPANTS

From the introduction of screening in 2000 through to 2017, 2 395 172 were invited to participate, of whom 1 487 999 participated at least once.

MAIN OUTCOME MEASURES

Incidence of CRC.

RESULTS

In the screening age range (50-74 years), CRC incidence peaked at 156.5 cases per 100 000 in 2010 after full roll-out of screening across Scotland but fell to 123.9 per 100 000 in 2017. However, under 50 years, there was a rise from 5.3 cases per 100 000 in 2000 to 6.8 per 100 000 in 2017. When CRC incidence was examined in those who had been offered screening, incidence fell in the participant group more than in the non-participant group after roll-out of screening was complete. Analysis of cumulative incidence demonstrated that CRC incidence in the participant group remained consistently below that of the non-participant from around 7 years of follow-up.

CONCLUSIONS

The incidence of CRC in Scotland has declined in the over 50 years age group but increased in younger people. It is likely that population screening has contributed to the reduction in CRC incidence in the over 50 years age group.