Fine-mapping analysis including over 254,000 East Asian and European descendants identifies 136 putative colorectal cancer susceptibility genes.

Genome-wide association studies (GWAS) have identified more than 200 common genetic variants independently associated with colorectal cancer (CRC) risk, but the causal variants and target genes are mostly unknown. We sought to fine-map all known CRC risk loci using GWAS data from 100,204 cases and 154,587 controls of East Asian and European ancestry. Our stepwise conditional analyses revealed 238 independent association signals of CRC risk, each with a set of credible causal variants (CCVs), of which 28 signals had a single CCV. Our cis-eQTL/mQTL and colocalization analyses using colorectal tissue-specific transcriptome and methylome data separately from 1299 and 321 individuals, along with functional genomic investigation, uncovered 136 putative CRC susceptibility genes, including 56 genes not previously reported. Analyses of single-cell RNA-seq data from colorectal tissues revealed 17 putative CRC susceptibility genes with distinct expression patterns in specific cell types. Analyses of whole exome sequencing data provided additional support for several target genes identified in this study as CRC susceptibility genes. Enrichment analyses of the 136 genes uncover pathways not previously linked to CRC risk. Our study substantially expanded association signals for CRC and provided additional insight into the biological mechanisms underlying CRC development.

Evaluation of an established colorectal robotic programme at an NHS district general hospital: audit of outcomes and systematic review of published data.

INTRODUCTION: Robotic-assisted surgery (RAS) offers potential advantages over traditional surgical approaches. This study aimed to assess outcomes from a district general hospital (DGH) robotic colorectal programme against published data. MATERIALS AND METHODS: The robotic programme was established following simulator, dry/wet lab training, and proctoring. We performed a case series analysing technical, patient, and oncological outcomes extracted from a prospective database of colorectal RAS cases (2015-2022). A registered systematic review (PROSPERO CRD42022300773; PubMed, Web of Science, EMBASE) of single-centre colorectal series from established robotic centres (n>200 cases) was completed and compared to local data using descriptive summary statistics. Risk of bias assessment was performed using an adapted version of the Cochrane ROBINS-I tool. RESULTS: Two hundred thirty-two RAS cases were performed including 122 anterior resections, 56 APERs, 19 rectopexies, and 15 Hartmann's procedures. The median duration was 325 (IQR 265-400) min. Blood loss was < 100 ml in 97% of cases with 2 (0.9%) cases converted to open. Complications (Clavien-Dindo 3-5) occurred in 19 (8%) patients, with 3 (1.3%) deaths in < 30 days. Length of stay was 7 (IQR 5-11) days. In 169 rectal cancer cases, there were 9 (5.3%) cases with a positive circumferential or distal margin and lymph node yield of 17 (IQR 13-24). A systematic review of 1648 abstracts identified 13 studies from established robotic centres, totaling 4930 cases, with technical, patient, and oncological outcomes comparable to our own case series. CONCLUSIONS: Outcomes from our robotic colorectal programme at a UK DGH are comparable with the largest published case series from world-renowned centres. Training and proctoring together with rolling audit must accompany the expansion of robotic surgery to safeguard outcomes.

Transcriptional dynamics of colorectal cancer risk associated variation at 11q23.1 correlate with tuft cell abundance and marker expression in silico.

Colorectal cancer (CRC) is characterised by heritable risk that is not well understood. Heritable, genetic variation at 11q23.1 is associated with increased colorectal cancer (CRC) risk, demonstrating eQTL effects on 3 cis- and 23 trans-eQTL targets. We sought to determine the relationship between 11q23.1 cis- and trans-eQTL target expression and test for potential cell-specificity. scRNAseq from 32,361 healthy colonic epithelial cells was aggregated and subject to weighted gene co-expression network analysis (WGCNA). One module (blue) included 19 trans-eQTL targets and was correlated with POU2AF2 expression only. Following unsupervised clustering of single cells, the expression of 19 trans-eQTL targets was greatest and most variable in cluster number 11, which transcriptionally resembled tuft cells. 14 trans-eQTL targets were found to demarcate this cluster, 11 of which were corroborated in a second dataset. Intra-cluster WGCNA and module preservation analysis then identified twelve 11q23.1 trans-eQTL targets to comprise a network that was specific to cluster 11. Finally, linear modelling and differential abundance testing showed 11q23.1 trans-eQTL target expression was predictive of cluster 11 abundance. Our findings suggest 11q23.1 trans-eQTL targets comprise a POU2AF2-related network that is likely tuft cell-specific and reduced expression of these genes correlates with reduced tuft cell abundance in silico.

Vitamin D treatment induces in vitro and ex vivo transcriptomic changes indicating anti-tumor effects.

Vitamin D deficiency is associated with risk of several common cancers, including colorectal cancer (CRC). Here we have utilized patient derived epithelial organoids (ex vivo) and CRC cell lines (in vitro) to show that calcitriol (1,25OHD) increased the expression of the CRC tumor suppressor gene, CDH1, at both the transcript and protein level. Whole genome expression analysis demonstrated significant differential expression of a further six genes after 1,25OHD treatment, including genes with established links to carcinogenesis GADD45, EFTUD1 and KIAA1199. Furthermore, gene ontologies relevant to carcinogenesis were enriched by 1,25OHD treatment (e.g., 'regulation of Wnt signaling pathway', 'regulation of cell death'), with common enriched processes across in vitro and ex vivo cultures including 'negative regulation of cell proliferation', 'regulation of cell migration' and 'regulation of cell differentiation'. Our results identify genes and pathways that are modifiable by calcitriol that have links to CRC tumorigenesis. Hence the findings provide potential mechanism to the epidemiological and clinical trial data indicating a causal association between vitamin D and CRC. We suggest there is strong rationale for further well-designed trials of vitamin D supplementation as a novel CRC chemopreventive and chemotherapeutic agent.

Improving the time to ileostomy closure following an anterior resection for rectal cancer in the UK.

AIM: Delayed closure of ileostomy following an anterior resection for rectal cancer in the UK is common. The aims of this study were (i) to investigate the variation in patient pathways between hospitals, (ii) to identify the key learning points from units with the shortest time to closure and (iii) to develop guidance for a pathway to minimize delay in ileostomy closure. METHOD: This was a mixed methods study. Thirty-eight colorectal units in the UK completed a short online survey. Nine colorectal units in Wales filled in an additional, expanded version of the survey. Semi-structured interviews were performed with clinicians from the six best performing units in terms of timely ileostomy closure. The optimal pathway suggested is based on the best evidence available and the Association of Coloproctology of Great Britain and Ireland guidelines. RESULTS: Qualitative analysis revealed that 5% of units (n = 2) have a local target time for ileostomy closure. Of all units, 90% (n = 34) would consider implementing a pathway if guidelines were developed. In-depth interviews highlighted the importance of a multidisciplinary approach, a dedicated coordinator to facilitate timely booking, and consensus on whether closure should be performed before or after adjuvant chemotherapy. CONCLUSION: There is a lack of national guidance in timing of contrast studies and ileostomy closure. Key aspects to consider are better information at consent regarding stoma closure timing, a dedicated person to track patients and the planning of contrast studies at discharge from initial surgery. With a dedicated approach closure of ileostomy within 10-12 weeks is feasible for most units.

Differential genetic influences over colorectal cancer risk and gene expression in large bowel mucosa.

Site-specific variation in colorectal cancer (CRC) incidence, biology and prognosis are poorly understood. We sought to determine whether common genetic variants influencing CRC risk might exhibit topographical differences on CRC risk through regional differences in effects on gene expression in the large bowel mucosa. We conducted a site-specific genetic association study (10 630 cases, 31 331 controls) to identify whether established risk variants exert differential effects on risk of proximal, compared to distal CRC. We collected normal colorectal mucosa and blood from 481 subjects and assessed mucosal gene expression using Illumina HumanHT-12v4 arrays in relation to germline genotype. Expression quantitative trait loci (eQTLs) were explored by anatomical location of sampling. The rs3087967 genotype (chr11q23.1 risk variant) exhibited significant site-specific effects-risk of distal CRC (odds ratio [OR] = 1.20, P = 8.20 × 10-20 ) with negligible effects on proximal CRC risk (OR = 1.05, P = .10). Expression of 1261 genes differed between proximal and distal colonic mucosa (top hit PRAC gene, fold-difference = 10, P = 3.48 × 10-57 ). In eQTL studies, rs3087967 genotype was associated with expression of 8 cis- and 21 trans-genes. Four of these (AKAP14, ADH5P4, ASGR2, RP11-342M1.7) showed differential effects by site, with strongest trans-eQTL signals in proximal colonic mucosa (eg, AKAP14, beta = 0.61, P = 5.02 × 10-5 ) and opposite signals in distal mucosa (AKAP14, beta = -0.17, P = .04). In summary, genetic variation at the chr11q23.1 risk locus imparts greater risk of distal rather than proximal CRC and exhibits site-specific differences in eQTL effects in normal mucosa. Topographical differences in genomic control over gene expression relevant to CRC risk may underlie site-specific variation in CRC. Results may inform individualised CRC screening programmes.

Gene Co-Expression Network Analysis Identifies Vitamin D-Associated Gene Modules in Adult Normal Rectal Epithelium Following Supplementation.

Colorectal cancer (CRC) is a common, multifactorial disease. While observational studies have identified an association between lower vitamin D and higher CRC risk, supplementation trials have been inconclusive and the mechanisms by which vitamin D may modulate CRC risk are not well understood. We sought to perform a weighted gene co-expression network analysis (WGCNA) to identify modules present after vitamin D supplementation (when plasma vitamin D level was sufficient) which were absent before supplementation, and then to identify influential genes in those modules. The transcriptome from normal rectal mucosa biopsies of 49 individuals free from CRC were assessed before and after 12 weeks of 3200IU/day vitamin D (Fultium-D3) supplementation using paired-end total RNAseq. While the effects on expression patterns following vitamin D supplementation were subtle, WGCNA identified highly correlated genes forming gene modules. Four of the 17 modules identified in the post-vitamin D network were not preserved in the pre-vitamin D network, shedding new light on the biochemical impact of supplementation. These modules were enriched for GO terms related to the immune system, hormone metabolism, cell growth and RNA metabolism. Across the four treatment-associated modules, 51 hub genes were identified, with enrichment of 40 different transcription factor motifs in promoter regions of those genes, including VDR:RXR. Six of the hub genes were nominally differentially expressed in studies of vitamin D effects on adult normal mucosa organoids: LCN2, HLA-C, AIF1L, PTPRU, PDE4B and IFI6. By taking a gene-correlation network approach, we have described vitamin D induced changes to gene modules in normal human rectal epithelium in vivo, the target tissue from which CRC develops.

The Value of Sentinel Lymph Node Mapping for the Staging of Node-Negative Colon Cancer: Propensity Score and Mediation Analyses.

Objectives: Mediation analysis to assess the protective impact of sentinel lymph node (SLN) mapping on prognosis and survival of patients with colon cancer through a more precise evaluation of the lymph node (LN) status. Background: Up to 20% of patients with node-negative colon cancer develop disease recurrence. Conventional histopathological LN examination may be limited in describing the real metastatic burden of LN. Methods: Data of 312 patients with stage I & II colon cancer was collected prospectively. Patients were either staged using intraoperative SLN mapping with multilevel sectioning and immunohistochemical staining of the SLN or conventional techniques. The value of the SLN mapping for the detection of truly node-negative patients was assessed using Cox regression and mediation analysis. Results: SLN mapping was performed in 143 patients. Disease recurrence was observed in 13 (9.1%) patients staged with SLN mapping and in 27 (16%) staged conventionally. Five-year overall survival (OS) rate was 82.7% (95% confidence interval [CI], 76.5-89.4%) with SLN mapping compared with 65.8% (95% CI, 58.8-73.7%). Five-year cancer-specific survival (CSS) was 95.1% (95% CI, 91.3-99.0%) with SLN mapping compared with 92.5% (95% CI, 88.0-97.2%). Node-negative staging with SLN mapping was associated with significantly better OS (hazard ratio [HR], 0.64; 95% CI, 0.56-0.72; P < 0.001) and CSS (HR, 0.49; 95% CI, 0.39-0.61; P < 0.001) in multivariate analysis. Mediation analysis confirmed a direct protective effect of SLN mapping on OS (HR, 0.78; 95% CI, 0.52-0.96; P < 0.01) and disease-free survival (DFS) (HR, 0.75; 95% CI, 0.48-0.89; P < 0.01). Conclusions: Staging performed by SLN mapping with multilevel sectioning provides more accurate results than conventional staging. The observed clinically relevant and statistically significant benefit in OS and DFS is explained by a more accurate detection of positive LN by SLN mapping.

The effect of vitamin D supplementation on survival in patients with colorectal cancer: systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Low circulating vitamin D levels are associated with poor colorectal cancer (CRC) survival. We assess whether vitamin D supplementation improves CRC survival outcomes. METHODS: PubMed and Web of Science were searched. Randomised controlled trial (RCTs) of vitamin D supplementation reporting CRC mortality were included. RCTs with high risk of bias were excluded from analysis. Random-effects meta-analysis models calculated estimates of survival benefit with supplementation. The review is registered on PROSPERO, registration number: CRD42020173397. RESULTS: Seven RCTs (n = 957 CRC cases) were identified: three trials included patients with CRC at outset, and four population trials reported survival in incident cases. Two RCTs were excluded from meta-analysis (high risk of bias; no hazard ratio (HR)). While trials varied in inclusion criteria, intervention dose and outcomes, meta-analysis found a 30% reduction in adverse CRC outcomes with supplementation (n = 815, HR = 0.70; 95% confidence interval (CI): 0.48-0.93). A beneficial effect was seen in trials of CRC patients (progression-free survival, HR = 0.65; 95% CI: 0.36-0.94), with suggestive effect in incident CRC cases from population trials (CRC-specific survival, HR = 0.76; 95% CI: 0.39-1.13). No heterogeneity or publication bias was noted. CONCLUSIONS: Meta-analysis demonstrates a clinically meaningful benefit of vitamin D supplementation on CRC survival outcomes. Further well-designed, adequately powered RCTs are needed to fully evaluate benefit of supplementation in augmenting 'real-life' follow-up and adjuvant chemotherapy regimens, as well as determining optimal dosing.

Protocol for a multicentre, dual prospective and retrospective cohort study investigating timing of ileostomy closure after anterior resection for rectal cancer: The CLOSurE of Ileostomy Timing (CLOSE-IT) study.

INTRODUCTION: A defunctioning ileostomy is often formed during rectal cancer surgery to reduce the potentially fatal sequelae of anastomotic leak. Once the ileostomy is closed and bowel continuity restored, many patients can suffer poor bowel function, that is, low anterior resection syndrome (LARS). It has been suggested that delay to closure can increase incidence of LARS which is known to significantly reduce quality of life. Despite this, within the UK, time to closure of ileostomy is not subject to national targets within the National Health Service and delay to closure exceeds 18 months in one-third of patients. Clinical factors, surgeon and patient preference or service pressures may all impact time to closure, yet to date no study has investigated this. The aim of this UK-wide study is to assess time to ileostomy closure and identify reasons for delays. METHODS AND ANALYSIS: A UK-wide multicentre prospective snapshot study, together with retrospective analysis of ileostomy closure through The Dukes' Club Research Collaborative including patients undergoing ileostomy closure in a 3-month period (April to June 2018) and all patients who underwent anterior resection and ileostomy formation over a historical 12-month period (2015). Time to closure and incidence of 'non-closure' will be calculated. Units will be surveyed to determine local clinical and management protocols and barriers to timely closure. Multivariate linear regression analysis will be used to determine factors significantly associated with delay to ileostomy closure. ETHICS AND DISSEMINATION: Study approved by the South West-Exeter Research Ethics Committee and the Health Research Authority. Study results will be submitted for presentation at international conferences and for publication in peer-reviewed journals. Results will be presented to and discussed with the patient and public representatives and relevant national bodies to facilitate the development of consensus guidelines on optimum treatment pathways.

Gallstone ileus and fatal gallstone coleus: the importance of the second stone.

A patient was admitted as an emergency with bowel obstruction. Recent medical history included an episode of gallstone ileus treated surgically by removal of an enteric calculus. On this admission, an obstructing calculus was removed from the descending colon (gallstone coleus) at laparotomy. However, the postoperative course was complicated by sepsis and the patient died. A CT scan on the second admission and cytology results from a liver abscess suggested gallbladder malignancy as the underlying cause of the cholecystoenteric fistula. The technical challenge and increased mortality associated with cholecystoenteric fistula repair supports simple enterolithotomy as the preferred management of gallstone ileus. However, this case supports the need for a systematic search for all enteric stones at laparotomy and consideration of concurrent or interval cholecystectomy and cholecystoenteric fistula repair to prevent recurrent gallstone ileus and determine underlying pathology.

An unexpected finding of a rare intrascrotal lesion: the sertoliform cystadenoma of the rete testis.

A 19-year-old man presented with a right testicular swelling. Testicular ultrasound demonstrated areas suspicious for malignancy and so it was decided to proceed for a right radical inguinal orchiectomy. Initial histological examination revealed a multiloculated cystic lesion at the area of the rete testis yet normal testicular parenchyma elsewhere. Specialist histological opinion was sought from the regional teratoma multi-disciplinary team which confirmed the diagnosis of a sertoliform cystadenoma, an extremely rare benign testicular neoplasm. The recognition of the benign nature of the mass enabled complete reassurance to be offered to the patient and avoided further oncological treatment.

Non-specific abdominal pain, an inconclusive CT scan and an unusual and puzzling finding at exploratory laparotomy.

A 71-year-old man presented to our hospital with generalised abdominal pain. Initial laboratory investigations were normal and an abdominal CT scan was inconclusive. The following day, persisting pain, generalised tenderness and haemodynamic instability prompted exploratory laparotomy. At laparotomy, two perforations of the proximal jejunum were identified caused by two 3 cm pieces of wood. The pieces of wood were retrieved and the perforations repaired primarily. The postoperative period was complicated by acute confusion but the patient went on to make a full recovery. On direct questioning, the patient was unable to explain the presence of wood within his gastrointestinal tract. One hypothesis was that he may have ingested this material during a period of acute confusion following an elective abdominal aortic aneurysm repair 8 years previously.

Cricopharyngeal dilatation for the long-term treatment of dysphagia in oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is a rare autosomal dominant, progressive degenerative muscle disorder featuring dysphagia with limited therapeutic options. The aim of this study was to evaluate the safety and efficacy of repeated endoscopic dilatation for OPMD over a 15-year period. All patients seen at our Regional Swallowing Clinic with OPMD confirmed by genetic analysis were included. Cricopharyngeal dilatation was performed as an outpatient procedure using a wire-guided 18-mm (54 Fr) Savary-Gilliard bougie with the patient under sedation. Patients were offered repeat endoscopic dilatation when symptoms recurred. Symptom severity prior to initial dilatation and at follow-up was evaluated using the Sydney Swallow Questionnaire (SSQ). Nine patients (7 female, 2 male) were included for analysis. Median total treatment period was 13 years (range = 3-15), median number of dilatations per patient was 7.2 (range = 1-16), and median interval between treatments was 15 months (range = 4.5-45). All patients recorded sustained symptom improvement. Mean SSQ score (out of 1,700) was 1,108.11 (SD ± 272.85) prior to first dilatation and 297.78 (SD ± 189.14) at last follow-up, representing a 73% decrease (95% CI = 52-94) in degree of dysphagia symptoms (paired t-test, P = 0.0001). All mean scores for individual questions also showed significant improvement (P < 0.05). No adverse events were reported with all patients maintaining oral feeding at last follow-up. Repeated cricopharyngeal dilatation is a safe, effective, well-tolerated, and long-lasting treatment for dysphagia in OPMD.

Thromboprophylaxis in trauma: a review of methods, evidence and guidelines.

Venous thromboembolism is a common cause of morbidity and mortality in trauma patients. Mechanical and pharmacological methods of thromboprophylaxis are available and guidelines relating to thromboprophylaxis in trauma include those published by the American College of Chest Physicians, the UK-based National Institute of Clinical Excellence, the Scottish Intercollegiate Guidelines Network and US-based Eastern Association for the Surgery of Trauma. All four guidelines have in common a recommendation for the use of low-molecular-weight heparin except where contraindicated. However, there is little consensus between guidelines relating to which mechanical methods should be used. Given the risk of thromboembolism in trauma patients and increasing interest in this condition clinicians should be aware of local and national guidelines relating to venous thromboembolism prevention in trauma patients. This paper reviews methods of thromboprophylaxis and compares guidelines relating to their use in trauma patients.

Campylobacterjejuni cholecystitis: a rare but significant clinical entity.

Cholecystitis caused by Campylobacter is rare with only 14 cases found in the literature. This case describes a 71-year-old man who presented with right hypochondrial abdominal pain due to a gangrenous gallbladder identified at laparotomy. Culture of a bile sample identified a slow-growing gram-negative bacterium identified as Campylobacter jejuni. After a poor clinical response, this identification allowed targeted antibiotic treatment resulting in a slow but successful recovery and discharge 17 days postoperatively. This case demonstrates the importance of considering rare organisms in severe acute cholecystitis and ensuring appropriate cultures are performed, particularly in those who fail to respond to initial antimicrobial treatment.