Comparison of genomic profiling of patient-matched primary colorectal and surgical resected distant metastatic (stage IV) colorectal carcinoma for drug actionability.

It is often difficult to obtain adequate tissue for genomic study from distant metastases for assessment of targeted therapy in colorectal carcinomas. The study aims to explore the genomic differences between matched distant metastatic colorectal carcinomas (mCRC) and primary carcinoma using surgical specimens of both with adequate tissue. Thirty-four paired primary and distant metastatic colorectal carcinoma samples (liver, ovary, and lung) were obtained from surgical excisions (not small biopsies) and are microsatellite stable. They were subjected to DNA sequencing using comprehensive next-generation sequencing. This included mutation concordance analysis and mutational signature analysis. The mutation concordance analysis showed 49.6% shared mutations between primary and metastatic tumours, with 23.0% mutations exclusive to primary tumours and 27.4% mutations exclusive to distant metastases. While many patients with KRAS/BRAF mutations had shared mutations, two cases had unique KRAS mutations in the primary tumours only. Additionally, TMB (tumour mutational burden) analysis revealed that half of the TMB-high (≥7.5 mutations/Mb) metastatic colorectal carcinomas had a low TMB (<7.5 mutations/Mb) in the primary tumours. The mutational signature analysis identified de novo signatures consistent with known single base substitution patterns such as SBS11 (alkylation agents) and SBS30 (base excision repair deficiency) post-chemotherapy. To conclude, this study demonstrates significant genomic variations in resected distant metastasis when compared to primary colorectal carcinomas when adequate tissue is available. This finding underscores the importance of considering these differences and selecting tissue for mutation analysis in planning targeted and effective treatment strategies for mCRC.

Correlation between KRAS Mutation and CTLA-4 mRNA Expression in Circulating Tumour Cells: Clinical Implications in Colorectal Cancer.

Combination strategies of KRAS inhibition with immunotherapy in treating advanced or recurrent colorectal carcinoma (CRC) may need to be assessed in circulating tumour cells (CTCs) to achieve better clinical outcomes. This study aimed to investigate the genomic variations of KRAS in CTCs and matched CRC tissues and compared mRNA expression of KRAS and CTLA-4 between wild-type and KRAS-mutated CTCs and CRC tissues. Clinicopathological correlations were also compared. Six known mutations of KRAS were identified at both codon 12 and codon 13 (c.35G>T/G12V, c.35G>A7/G12D, c.35G>C/G12A, c.34G>A/G12S, c.38G>C/G13A, and c.38G>A/G13D). Three CTC samples harboured the identified mutations (16.7%; 3/18), while fifteen matched primary tumour tissues (65.2%, 15/23) showed the mutations. CTCs harbouring the KRAS variant were different from matched CRC tissue. All the mutations were heterozygous. Though insignificant, CTLA-4 mRNA expression was higher in patients carrying KRAS mutations. Patients harbouring KRAS mutations in CTCs were more likely to have poorly differentiated tumours (p = 0.039) and with lymph node metastasis (p = 0.027) and perineural invasion (p = 0.014). KRAS mutations in CTCs were also significantly correlated with overall pathological stages (p = 0.027). These findings imply the genetic basis of KRAS with immunotherapeutic target molecules based on a real-time platform. This study also suggests the highly heterogeneous nature of cancer cells, which may facilitate the assessment of clonal dynamics across a single patient's disease.

Correction: Aktar et al. Gene Expression Analysis of Immune Regulatory Genes in Circulating Tumour Cells and Peripheral Blood Mononuclear Cells in Patients with Colorectal Carcinoma. Int. J. Mol. Sci. 2023, 24, 5051.

Faysal Bin Hamid was not included as an author in the original publication [...].

Gene Expression Analysis of Immune Regulatory Genes in Circulating Tumour Cells and Peripheral Blood Mononuclear Cells in Patients with Colorectal Carcinoma.

Information regarding genetic alterations of driver cancer genes in circulating tumour cells (CTCs) and their surrounding immune microenvironment nowadays can be employed as a real-time monitoring platform for translational applications such as patient response to therapeutic targets, including immunotherapy. This study aimed to investigate the expression profiling of these genes along with immunotherapeutic target molecules in CTCs and peripheral blood mononuclear cells (PBMCs) in patients with colorectal carcinoma (CRC). Expression of p53, APC, KRAS, c-Myc, and immunotherapeutic target molecules PD-L1, CTLA-4, and CD47 in CTCs and PBMCs were analysed by qPCR. Their expression in high versus low CTC-positive patients with CRC was compared and clinicopathological correlations between these patient groups were analysed. CTCs were detected in 61% (38 of 62) of patients with CRC. The presence of higher numbers of CTCs was significantly correlated with advanced cancer stages (p = 0.045) and the subtypes of adenocarcinoma (conventional vs. mucinous, p = 0.019), while being weakly correlated with tumour size (p = 0.051). Patients with lower numbers of CTCs had higher expression of KRAS. Higher KRAS expression in CTCs was negatively correlated with tumour perforation (p = 0.029), lymph node status (p = 0.037), distant metastasis (p = 0.046) and overall staging (p = 0.004). CTLA-4 was highly expressed in both CTCs and PBMCs. In addition, CTLA-4 expression was positively correlated with KRAS (r = 0.6878, p = 0.002) in the enriched CTC fraction. Dysregulation of KRAS in CTCs might evade the immune system by altering the expression of CTLA-4, providing new insights into the selection of therapeutic targets at the onset of the disease. Monitoring CTCs counts, as well as gene expression profiling of PBMCs, can be helpful in predicting tumour progression, patient outcome and treatment.

Comprehensive assessment of actionable genomic alterations in primary colorectal carcinoma using targeted next-generation sequencing.

BACKGROUND: The clinical utility of comprehensive genomic profiling (CGP) for guiding treatment has gradually become the standard-of-care procedure for colorectal carcinoma (CRC). Here, we comprehensively assess emerging targeted therapy biomarkers using CGP in primary CRC. METHODS: A total of 575 primary CRCs were sequenced by ACTOnco® assay for genomic alterations, tumour mutational burden (TMB), and microsatellite instability (MSI). RESULTS: Eighteen percent of patients were detected as MSI-High (MSI-H), and the remaining cases were classified as microsatellite stable (MSS). Driver mutation prevalence in MSS CRCs were APC (74%), TP53 (67%), KRAS (47%), PIK3CA (21%) and BRAF (13%). The median TMBs for MSI-H and MSS patients were 37.8 mutations per mega base (mut/Mb) and 3.9 mut/Mb, respectively. Forty-seven percent of MSI-H CRC harboured at least one loss-of-function mutations in genes that may hamper immune checkpoint blockade. Among MSS RAS/RAF wild-type CRCs, 59% had at least one actionable mutation that may compromise the efficacy of anti-EGFR therapy. For late-stage CRC, 51% of patients are eligible for standard care actionability and the remaining 49% could be enrolled in clinical trials with investigational drugs. CONCLUSIONS: This study highlights the essential role of CGP for identifying rational targeted therapy options in CRC.

Heme oxygenase-1 & 2 and their potential contribution in heme induced colorectal carcinogenesis.

BACKGROUND: Literature suggests Heme oxygenase (HO) system to be a double-edged sword which can promote both cytoprotection as well as carcinogenicity. The aim of this study was to investigate the role of heme in HO-1 and HO-2 induced colorectal carcinogenesis and the clinicopathological significance of their expressions in patients with colorectal carcinoma (CRC). METHODS: HO-1 and HO-2 expression alterations in normal colonic epithelial (FHC) and colon cancer cells (SW480) were explored following treatment with 0 µM, 25 µM, 100 µM and 250 µM concentrations of hemin, using qPCR. Fifty paired CRC and adjacent non-neoplastic samples were subjected to qPCR to determine the HO-1 and HO-2 expression. Clinicopathological associations of HO-1 and HO-2 expression levels were determined. RESULTS: Low concentrations of hemin caused upregulation and high concentration caused downregulation of HO-1 expression, whereas HO-2 expression was significantly downregulated with all hemin concentrations in FHC. HO-1 expression in SW480 was increased with all hemin concentrations and HO-2 expression was downregulated at the highest hemin concentration. HO-1 and HO-2 expressions in adjacent non-neoplastic tissue was significantly higher than that of CRC. Expression of HO-1 was significantly higher than HO-2, in both CRC and adjacent non-neoplastic tissue. Sex, HFE expression and lymph-vascular invasion were significantly correlated with HO-1 expression. HO-2 expression showed significant associations with staging, local spread and recurrence of tumour. CONCLUSION: HO-1 and HO-2 expression is respectively induced and repressed by exogenous hemin in normal colon and colon cancer cells. HO-1 and HO-2 expression profiles in CRC are correlated with the assessed clinicopathological features of CRC, suggesting the possible implications of HO expression status in CRC pathogenesis.

AHR gene expression and the polymorphism rs2066853 are associated with clinicopathological parameters in colorectal carcinoma.

The relationship between red and processed meat and its risk toward colorectal carcinoma (CRC) is not fully explored in literature. Polycyclic aromatic hydrocarbons (PAHs) are procarcinogenic molecules that are ingested with meat cooked at high temperatures. The metabolic conversion of PAHs to carcinogenic diol epoxides is in part mediated by the aryl hydrocarbon receptor (AhR)-dependent induction of CYP1A1. This study aims to examine the expression profiles and polymorphisms of the AHR (aryl hydrocarbon receptor) gene which is involved in the metabolic conversion of PAHs in patients with CRC. Genetic analysis was done in matched cancer and non-neoplastic tissues from 79 patients diagnosed with CRCs. Low AHR mRNA expression was associated with mucinous colorectal adenocarcinoma. Exon 10 of AHR showed that 27% of patients had the rs2066853 single-nucleotide polymorphism resulting in an arginine-to-lysine change at codon 554. This variant was significantly associated with a lower likelihood of perineural invasion, presence of synchronous cancer, and multiple colorectal polyps. Furthermore, rs2066853 individuals were significantly more likely to be of more advanced age and have a more favorable tumor grade and pathological stage. These results imply the pathogenic roles of AHR in PAH-associated colorectal carcinogenesis.

Polymorphisms in PAH metabolising enzyme CYP1A1 in colorectal cancer and their clinicopathological correlations.

CYP1A1 enzyme is integral to the biotransformation of polycyclic aromatic hydrocarbons to carcinogenic compounds. This study aimed to screen mutations in exon 7 (ex7) of CYP1A1 and investigate its clinicopathological correlations in fresh tissue samples from 85 patients (42 women; 43 men) with colorectal carcinoma (CRC). Tumour tissues and matched non-neoplastic mucosa tissues were collected prospectively. Genomic DNA was extracted from all tissues, and subject to high-resolution melt curve analysis for CYP1A1-ex7. Sanger sequencing was employed to detect specific mutations. Three known single nucleotide polymorphisms (SNPs) were identified in both tumour and matched non-neoplastic tissue for the same individual. Of the 85 patients, one third (n = 28) harboured either rs1048943, rs1799814, or rs41279188. Patients who had a SNP at ex7 of CYP1A1 were significantly more likely to be over 65 years of age (p = 0.015). Furthermore, individuals harbouring a SNP at exon7 showed a low incidence of perineural cancer infiltration (p = 0.025) when compared to the wild-type population. Overall, polymorphisms at exon 7 of CYP1A1 are present in patients with CRC and associated with a few clinicopathological characteristics.

Omentoplasty to reduce anastomotic leak in colorectal surgery: a meta-analysis.

BACKGROUND: Anastomotic leaks (AL) remain a devastating complication following intestinal anastomoses resulting in increased morbidity and mortality. Wrapping the anastomosis with omentum may be protective although data are conflicting. We performed a meta-analysis to assess the effect of omentoplasty on colorectal anastomoses. METHODS: PubMed, EMBASE and Cochrane databases were searched for relevant articles from inception until August 2021. All randomized controlled trials (RCT) that reported on the use of omentoplasty in colon and rectal surgery were included. The primary outcome was rate of overall AL while secondary outcomes included clinical and radiological AL, overall reoperation and mortality. Random effects models were used to calculate pooled effect size estimates. Sensitivity analyses were also performed. RESULTS: Four RCTs were included capturing 1067 patients. The mean (SD) age of the cohort was 61.5 (±14.8) years. On random effects analysis, omentoplasty reduced rate of overall (OR 0.43, 95% CI = 0.21-0.87, p = 0.02) and clinical AL (OR = 0.35, 95% CI = 0.15-0.81, p = 0.01). However, there was no difference in radiological AL (OR = 0.77, 95% CI = 0.40-1.47, p = 0.42), overall reoperations (OR 0.48, 95% CI = 0.18-1.32, p = 0.16) or mortality (OR 0.52, 95% CI = 0.12 to-2.18, p = 0.37). On sensitivity analysis, assessing rectal anastomoses only, the results for overall AL remained similar (OR 0.28, 95% CI = 0.12-0.61, p = 0.002). CONCLUSION: Although omentoplasty appears to reduce the rate of overall and clinical AL, the heterogeneity in the data prevents definitive recommendations from being made. Further well-designed trials are needed to investigate this technique.

Incidence of Clostridioides difficile in patients post loop ileostomy reversal in an Australian tertiary hospital: a retrospective study.

INTRODUCTION: The purpose of a loop ileostomy is to temporarily divert faeces away from a distal anastomosis, to reduce the consequences of anastomotic leak. This ultimately requires a second procedure to restore bowel continuity, which confers risk of complications including the development of Clostridioides difficile infection (CDI). It is hypothesized that patients who undergo loop ileostomy reversal are at increased risk of CDI when compared with other patients undergoing elective colorectal surgical procedures, and that these patients also experience an increased length of stay (LOS). METHODS: A retrospective cohort study was performed on all patients who underwent loop ileostomy reversal at the Gold Coast Hospital and Health Service between 1 January 2012 and 31 December 2019. RESULTS: Two hundred and twenty-eight patients were identified. Eight tested positive for CDI on faecal PCR (3.51%), a higher incidence than that in patients who underwent an elective colorectal surgical procedure during the same period (0.83%) (RR = 4.23). Additionally, median LOS for ileostomy reversal patients was significantly increased in those who also had CDI when compared with those without CDI (11 versus 4 days; P = 0.0003). CONCLUSION: The study confirmed that the incidence of CDI was higher in those who underwent ileostomy reversal when compared with an otherwise comparable hospital population (elective colorectal surgery patients). Additionally, those patients who underwent ileostomy reversal and had CDI experienced an increased LOS which translates to increased cost to the healthcare system. Further investigation into pre-operative screening and prophylactic antibiotics should be considered as a measure to mitigate this post-operative complication.

Identification of novel mutations and functional impacts of EPAS1 in colorectal cancer.

Endothelial PAS domain-containing protein 1 (EPAS1) has implications in many cancers. However, the molecular behaviours, functional roles and mutational status of EPAS1 have never been studied in colorectal carcinoma (CRC). The study aims to examine the genetic alterations and functional roles of EPAS1 in CRC. In addition, the clinical impacts of EPAS1 in CRC were studied. Significant EPAS1 DNA amplification (63.4%; n = 52/82) and consequent mRNA overexpression (72%; n = 59/82) were noted in patients with CRC. In CRC, 16% (n = 13/82) of the patients had mutations in the EPAS1 coding sequence and most of the mutated samples exhibited aberrant DNA changes and mRNA overexpression. We have identified two novel variants, c.1084C>T; p.L362L and c.1121T>G; p.F374C in CRC. These EPAS1 aberrations in CRC were correlated with clinicopathological parameters, including tumour size, histological grade, T-stages, cancer perforation as well as the presence of synchronous cancer. Also, reduced cell proliferation, wound healing, migration and invasion were noted in colon cancer cells followed by EPAS1 silencing. To conclude, the results obtained from the current study indicated that EPAS1 plays important role in colorectal carcinogenesis, thus, could be useful as a prognostic marker and as a target for therapy development.

Prophylactic mesh placement at index permanent end colostomy creation to prevent parastomal hernia-an updated meta-analysis.

BACKGROUND: Debate persists regarding the efficacy of prophylactic mesh insertion (PMI) at index permanent stoma creation to reduce the rate of parastomal hernia (PSH). This meta-analysis aimed to appraise all the latest evidence from newly published randomized controlled trials (RCTs) on PMI for PSH prevention. METHODS: PubMed, EMBASE, and Cochrane databases were searched for relevant articles from inception until November 2020. All RCTs that reported on PMI at end colostomy creation with ≥ 12 months follow-up were included. The primary objective was the rate of clinical and radiological PSH while secondary objectives included number of PSH requiring repair and stoma (or mesh)-related complications. Random effects models were used to calculate pooled effect size estimates. Sensitivity analyses were also performed. RESULTS: Eleven RCTs were included capturing 1097 patients. The mean (SD) age was 67.9 (±9.4) years. On random effects analysis, prophylactic mesh appeared to reduce the rate of both clinical (OR = 0.27, 95% CI = 0.12 to 0.61, p = 0.002) and radiological (OR = 0.39, 95% CI = 0.24 to 0.65, p = 0.0002) PSH. However, there was no difference in number of PSH requiring repair or stoma-related complications. On sensitivity analysis, when focusing on low-risk of bias studies, the benefit of prophylactic mesh in the retrorectus space was lost for both clinical (OR = 0.97, 95% CI = 0.62 to 1.51, p = 0.89) and radiological PSH (OR = 0.74, 95% CI = 0.46 to 1.18, p = 0.20). CONCLUSION: PMI may reduce the rate of subsequent PSH. However, further studies are required to confirm these findings and to establish the optimal mesh position and shape before definite recommendations can be made.

Enumeration, characterisation and clinicopathological significance of circulating tumour cells in patients with colorectal carcinoma.

BACKGROUND: The purposes of the study were to enumerate and characterise the circulating tumour cell (CTC) and cluster/micro-emboli (CTM) in blood from patients with colorectal carcinoma (CRC) as well as to investigate their clinical relevance. METHODS: Peripheral blood of six healthy donors (control) and sixty-two patients with CRC were collected to isolate CTCs by an immunomagnetic negative selection approach. EPCAM and cytokeratin 18 (CK18) antibodies were used to identify the CTCs. The size and the phenotypic variations were evaluated to characterise these isolated CTCs. Additionally, mRNA expressions of the CTCs and the corresponding primary carcinoma were assessed using a multi-gene panel to determine the cellular heterogeneities between CTCs and primary carcinoma. RESULTS: We detected CTCs and CTMs in 72% (41/57) and 32% (18/57) of the patients with CRC, respectively. The total number and length were significantly higher (p<0.0001) in the CTCs than the CTMs. CTCs, especially EPCAMPositiveCK18Posositve subclones, were detected more in the patients with advanced pathological cancer stages when compared to those with early cancer stages (mean: 12.5 vs 4.0, p=0.0068). mRNA profiling of CTCs unveiled three different CTC subtypes expressing epithelial, epithelium-mesenchymal transition (EMT) and stemness signatures, which were different from those of the primary carcinoma. The expressions of EPCAM, HRAS, BRAF, TP53, SLUG, TWIST1, CD44 and MMP9 of CTCs were altered when compared to the primary tumours in patients with CRC. CONCLUSION: Our findings provide insights into the biology of the CTC, presence of heterogeneous CTC populations in CRC and differential expression of genes in different pathological stages of CTC which can improve the management of patients with CRC.

Genetic Heterogeneity of Single Circulating Tumour Cells in Colorectal Carcinoma.

The aim of the present study was to isolate and investigate the genetic heterogeneities in single circulating tumour cells (CTCs) from patients with colorectal carcinoma (CRC). Twenty-eight single CTCs were collected from eight patients with CRC using a negative immunomagnetic enrichment method. After validation with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression in 3 colon cancer cell lines, a panel of 19 genes were used to analyse the single CTCs (n = 28), primary colorectal carcinoma tissues (n = 8) and colon carcinoma cells (n = 6) using real-time qPCR. Genetic heterogeneities were assessed by comparing gene expression profiles of single CTCs from the different patients and in the same patient, respectively. Genetic profiling of the single CTCs showed extensive heterogeneities of the selected genes among the CTCs. Hierarchical clustering analyses exhibited two clusters of CTCs with differentially expressed genes, which highlighted different modifications from the primary carcinomas. Further, the genetic heterogeneities were observed between different patients or in the same patient. Finally, AKT1 expression was significantly (p = 0.0129) higher in single CTCs from CRC of advanced pathological stages (III or IV) CRC than in CTCs from CRC of early stages (I or II). Our findings suggest that single-cell genetic analysis can monitor the genetic heterogeneities and guide the personalised therapeutic targets in clinical sectors.

Overexpression of family with sequence similarity 134, member B (FAM134B) in colon cancers and its tumor suppressive properties in vitro.

This study aims to investigate the overexpression-induced properties of tumor suppressor FAM134B (family with sequence similarity 134, member B) in colon cancer, examine the potential gene regulators of FAM134B expression and its impact on mitochondrial function. FAM134B was overexpressed in colon cancer and non-neoplastic colonic epithelial cells. Various cell-based assays including apoptosis, cell cycle, cell proliferation, clonogenic, extracellular flux and wound healing assays were performed. Western blot analysis was used to confirm and identify potential interacting partners of FAM134B in vitro. Immunohistochemistry and qPCR were employed to determine the expressions of MIF and FAM134B, respectively, on 63 patients with colorectal carcinoma. Results showed that FAM134B is involved in the cell cycle and mitochondrial function of colon cancer. Overexpression of FAM134B was coupled with increased expression levels of APC, p53, and MIF. Increased expression of both APC and p53 further validates the potential role of tumor suppressor FAM134B in regulating cancer progression through the WNT/ß-catenin signaling pathway. In approximately 70% of the patients with colorectal cancer, FAM134B downregulation was correlated with MIF protein overexpression while the remaining 30% showed concurrent expression of FAM134B and MIF (P = .045). High expression of MIF coupled with low expression of FAM134B is associated with microsatellite instability status in colorectal carcinomas (P = .049). FAM134B may exert its tumor suppressive function through affecting cell cycle, mitochondrial function via potentially interacting with MIF and p53.

Increasing rate of colorectal cancer in younger patients: a review of colonoscopy findings in patients under 50 at a tertiary institution.

BACKGROUND: In Australia, colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer death. It is more common in patients over 50 years, with previous evidence showing patients under 50 years account for only 9% of CRC. However, recent Australian and International studies have shown an increase in CRC incidence in patients under 50 years of age. The main aim of this study was to analyse the incidence of CRC in patients under 50 and to determine if screening would be beneficial in this population. METHODS: A retrospective cohort study was performed on all patients under 50 years of age who underwent a colonoscopy, performed by a colorectal surgeon, at the Gold Coast Hospital and Health Service between January 2013 and December 2017. RESULTS: A total of 557 patients were included in the study; 120 (21.5%) colonoscopies had a significant finding (CRC or adenoma with malignant potential). 1.9% of patients were diagnosed with CRC, all were symptomatic at time of diagnosis, the majority were stage 3 or 4. CONCLUSION: A total of 1.9% of patients under 50 who underwent colonoscopy were diagnosed with CRC, whilst 21.5% of patients had significant findings. These rates are greater than previously quoted figures and data for patients under 50, and provides evidence to support lowering of the CRC faecal occult blood testing screening age.

Transanal total mesorectal excision the Gold Coast experience: learning curve and comparison to traditional technique.

BACKGROUND: Laparoscopic and open techniques in rectal cancer are well-published, however, technical challenges remain for mid to low rectal cancer resections in the narrow pelvis. Transanal total mesorectal excision (taTME) has been pioneered to potentially circumvent these challenges. The aims of this study were to evaluate the learning curve associated with our first cases of taTME as well as compare outcomes to that of conventionally performed rectal resections. METHODS: This was a single-centre retrospective study with data collated from all elective resections by the colorectal unit from 2015 to 2017. Primary outcome was completeness of total mesorectal excision and secondary outcomes were intra- and post-operative morbidity and mortality. RESULTS: A total of 43 patients were identified. Of which, 20 underwent taTME. Mesorectal completeness was obtained in only 47.4% in the taTME group compared to 78.3% in the anterior resection group (p = 0.115). 5.9% of patients in our taTME group had positive circumferential resection margin compared to nil in the anterior resection. Conversion rates were greater in the taTME group (15% versus 0%; 0.028). Operative time, length of stay and clavien IV and V complications were greater in the taTME group. CONCLUSION: This study highlights the difficulty in introducing a novel technique given the learning curve. Our results would expect to improve with increased caseload.

Delay to Adjuvant Chemotherapy: Survival and Recurrence in Patients of Rectal Cancer Treated with Neo-adjuvant Chemoradiotherapy and Surgery.

PURPOSE: This aim of the study is to evaluate the survival function and hazard risks of delayed adjuvant chemotherapy (ChT) to distant recurrence risk in patients with non-metastatic rectal cancer treated with neoadjuvant chemoradiotherapy (CRT) and surgery. METHODS: A single tertiary hospital retrospective cohort study of a duration of 5 years between January 2012 and December 2016 was performed. As no previous study shown a temporal relationship of delay to adjuvant/systemic ChT leading to increased risk of metastatic disease, we compared between our proposed cut-off with the median and mean value determined by our dataset. Time to event analysis and log rank tests were conducted. RESULTS: A total of 269 patients with rectal cancer were identified. Two hundred eighteen patients were ineligible, leaving 51 patients for final analysis. Patients in the non-delayed group at 23 (proposed) and 25 (median) weeks' cut-off reported better 5 years' disease free survival (DFS) compared with the delayed group by 4.1% and 0.8%. Inversely, at the cut-off 28 (mean) weeks, the delayed group had a better DFS by 4.4%. Females and patients less than 60 years old had better 5-year DFS by 22.8% and 24%. Delayed group has a higher hazard risk ratio (HR) of 1.28 of distant recurrence compared with non-delayed at 23 weeks' cut-off. CONCLUSION: This study has demonstrated delaying a patient to adjuvant ChT will lower their DFS and increase their HR compared with those whose treatment is not delayed. We have long been too focused on local control; hence, priority needs to be shifted to efforts in managing potential distant disease in a timely manner.

Characterization of Mucosa-Associated Microbiota in Matched Cancer and Non-neoplastic Mucosa From Patients With Colorectal Cancer.

Colonic microbiota play important roles in the development of colorectal cancer. We aim to characterise the mucosa-associated microbiota in the tumour as well as the matched non-neoplastic mucosa from patients with colorectal cancer. Microbiota profiling in these samples was done using high-throughput 16S rRNA amplicon sequencing. Our results showed that the microbiota richness and diversity were similar between the tumour and non-neoplastic mucosae. Linear discriminant analysis effect size (LEfSe) analysis identified Fusobacterium and Campylobacter as the key genera of the tumour while Brevundimonas as the key genus of the non-neoplastic mucosa. In patients with shorter survival period, the relative abundance of Fusobacterium and Campylobacter was significantly higher in the tumour. Besides, regardless of the sites, tumour showed higher abundance of Fusobacterium. On the other hand, the relative abundance of Brevundimonas was significantly lower in the tumour. When validated with quantitative ddPCR, we found the absolute numbers of both Fusobacterium and F. nucleatum were significantly higher in the carcinoma from patients with shorter survival period, conventional type of adenocarcinoma in the distal portion of the large intestine (descending colon, sigmoidal colon, and rectum). In conclusion, our study showed a compositional alteration in the mucosa-associated microbiota in the tumour, which may contribute to the progression of colorectal cancer.

Subcutaneous neostigmine appears safe and effective for acute colonic pseudo-obstruction (Ogilvie's syndrome).

BACKGROUND: Intravenous neostigmine is a well-established treatment for acute colonic pseudo-obstruction (ACPO). Its use is hampered by the perceived requirement for continuous cardiac monitoring, and patients are often transferred to high-dependency units for close observation during treatment. Subcutaneous neostigmine has the potential to minimize adverse cardiovascular effects while maintaining efficacy. This study aims to assess the safety of subcutaneous neostigmine on ward inpatients with ACPO monitored with standard nursing care. METHODS: This is a retrospective case series of 30 patients with ACPO who were treated with subcutaneous neostigmine between August 2008 and October 2012. Data were collected prospectively. All patients were diagnosed using clinical examination and radiology and were assessed for contraindications to neostigmine. Patients were treated on regular wards and monitored with standard nursing observations. The main outcomes were time to flatus and bowels working and complications. RESULTS: No serious complications such as clinically evident bradycardia were encountered. Ninety-three percent of patients had clinically successful resolution of ACPO. Two patients (7%) developed caecal tenderness and proceeded to colonoscopic decompression, which was successful in both instances. CONCLUSIONS: Subcutaneous neostigmine appears to be safe for the treatment of ACPO. No clinically evident serious adverse events occurred, meaning continuous cardiac monitoring as a routine may not be necessary. In our cohort, we achieved similar success rates compared with reported rates using intravenous neostigmine.