Lipidomic Profiling of Colorectal Lesions for Real-Time Tissue Recognition and Risk-Stratification Using Rapid Evaporative Ionization Mass Spectrometry

OBJECTIVE

Rapid evaporative ionization mass spectrometry (REIMS) is a metabolomic technique analyzing tissue metabolites, which can be applied intraoperatively in real-time. The objective of this study was to profile the lipid composition of colorectal tissues using REIMS, assessing its accuracy for real-time tissue recognition and risk-stratification.

SUMMARY BACKGROUND DATA

Metabolic dysregulation is a hallmark feature of carcinogenesis; however, it remains unknown if this can be leveraged for real-time clinical applications in colorectal disease.

METHODS

Patients undergoing colorectal resection were included, with carcinoma, adenoma and paired-normal mucosa sampled. Ex vivo analysis with REIMS was conducted using monopolar diathermy, with the aerosol aspirated into a Xevo G2S QToF mass spectrometer. Negatively charged ions over 600 to 1000 m/z were used for univariate and multivariate functions including linear discriminant analysis.

RESULTS

A total of 161 patients were included, generating 1013 spectra. Unique lipidomic profiles exist for each tissue type, with REIMS differentiating samples of carcinoma, adenoma, and normal mucosa with 93.1% accuracy and 96.1% negative predictive value for carcinoma. Neoplasia (carcinoma or adenoma) could be predicted with 96.0% accuracy and 91.8% negative predictive value. Adenomas can be risk-stratified by grade of dysplasia with 93.5% accuracy, but not histological subtype. The structure of 61 lipid metabolites was identified, revealing that during colorectal carcinogenesis there is progressive increase in relative abundance of phosphatidylglycerols, sphingomyelins, and mono-unsaturated fatty acid-containing phospholipids.

CONCLUSIONS

The colorectal lipidome can be sampled by REIMS and leveraged for accurate real-time tissue recognition, in addition to riskstratification of colorectal adenomas. Unique lipidomic features associated with carcinogenesis are described.

Identification and characterization of four bacteriome- and mycobiome-derived subtypes in tumour and adjacent mucosa tissue of colorectal cancer patients

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Background: The bacteriome and mycobiome, collectively referred to as the microbiome, is a key player in CRC pathogenesis, progression and response to chemotherapy, radiotherapy and immunotherapy. Microbial modulation and exacerbation in CRC is likely attributable to alterations of composition and diversity of the microbiome rather than to a single microbial species. We therefore systematically investigated alterations in the bacteriome and mycobiome of CRC patients in tumours and matched adjacent mucosa resulting in the identification of microbiome-based subtypes associated with host clinico-pathological and molecular characteristics. Methods: We estimated bacterial and fungal composition from RNA sequencing experiments using a validated subtractive method ( PathSeq) in in-house and publicly available cohorts. We evaluated the quality of the microbial estimates with two sets of orthogonal analysis determining i) the agreement with composition from an independent method and ii) retrieval of expected clinically-relevant microbial signatures. Diversity and composition of bacteriome and mycobiome of tumour and adjacent mucosa, and resulting subtypes were computationally deconvoluted using > 10,000 samples. Results: The bacteriome of tumours had higher dominance and lower ɑ-diversity compared to matched adjacent local and distant mucosa. Tumours were enriched with Proteobacteria (Gammaproteobacteria class), Fusobacteria (including Fusobacterium Nucleatum species) and Basidiomycota fungi (Malasseziaceae family). Tumours were depleted of Bacteroidetes (Bacteroidia class), Firmicutes (Clostridia class) and Ascomycota (Sordariomycetes and Saccharomycotina). Tumours and adjacent mucosa samples were classified into 4 microbial subtypes, termed C1 to C4, based on the bacteriome and mycobiome composition. The bacterial Propionibacteriaceae, Enterobacteriaceae, Fusobacteriaceae, Bacteroidaceae and Ruminococcaceae along with the fungal Malasseziaceae, Saccharomycetaceae and Aspergillaceae were among the key families driving the microbial subtyping. Microbial subtypes were associated with distinct tumour histology and patient phenotypes and served as independent prognostic marker for disease-free survival. Key associations between microbial subtypes and alterations in host immune response and signalling pathways were validated in the TCGA pan-cancer cohort. The microbial subtyping demonstrated stratification value in the pan-cancer settings beyond merely representing differences in survival by cancer type. Conclusions: This study demonstrates the translational potential of microbial subtyping in CRC patient stratification, and provides avenues to design tailored microbiota modulation therapy to further precision oncology.

Gut Microbiota Modulation of Efficacy and Toxicity of Cancer Chemotherapy and Immunotherapy

Accumulating evidence supports not only the functional role of the gut microbiome in cancer development and progression but also its role in defining the efficacy and toxicity of chemotherapeutic agents (5-fluorouracil, cyclophosphamide, irinotecan, oxaliplatin, gemcitabine, methotrexate) and immunotherapeutic compounds (anti-programmed death-ligand 1/anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte-associated antigen 4). This evidence is supported in numerous in vitro, animal, and clinical studies that highlight the importance of microbial mechanisms in defining therapeutic responses. The microbiome therefore shapes oncologic outcomes and is now being leveraged for the development of novel personalized therapeutic approaches in cancer treatment. However, if the microbiome is to be successfully translated into next-generation oncologic treatments, a new multimodal model of the oncomicrobiome must be conceptualized that incorporates gut microbial cometabolism of pharmacologic agents into cancer care. The objective of this review is therefore to outline the current knowledge of oncologic pharmacomicrobiomics and to describe how the multiparametric functions of the gut microbiome influence treatment response across cancer types. The secondary objective is to propose innovative approaches for modulating the gut microbiome in clinical environments that improve therapy efficacy and diminish toxic effects derived from antineoplastic agents for patient benefit.

Defeating Cancel Culture in Surgical Site Infection Research: A Plea to Include Microbial Cultures and Antibiotic Sensitivity Data

Background: Despite advances in infection control measures, surgical site infections (SSIs) remain a real and present danger to patients. In most studies addressing SSI prevention measures, recommendations are often made in the absence of information such as culture results, the antibiotic agents used for prophylaxis, and antibiotic sensitivity data. The aim of this study is to document this latter claim by reviewing studies published in the last five years in highly read and cited surgical journals. Methods: A systematic review evaluating SSIs from four highly cited surgical journals, Annals of Surgery, the British Journal of Surgery, JAMA Surgery, and the Journal of the American College of Surgeons was conducted for articles published between 2016 and 2021. We focused our analysis on the following key features: how SSI is defined; bacterial culture information; antibiotic sensitivity data; and identification of the antibiotic chosen for prophylaxis. We hypothesized that, in most cases among the journals queried, this information would be unavailable. Results: Of the 71 studies included, 32 diagnosed SSIs based on criteria developed by the U.S. Centers for Disease Control and Prevention while five provided no definition of SSI. Of the 27 articles recommending increasing antibiotic usage, only one study performed antibiotic sensitivity testing to guide the antibiotic choice. Of 71 studies reviewed, only one reported all key features we considered to be important for SSI antibiotic decision-making; 46 reported none of the key features. Conclusions: Among publications addressing SSIs in four highly cited surgical journals, key information regarding diagnosis and with which to base antibiotic recommendations, is routinely unavailable.

A Delphi consensus statement for digital surgery

The use of digital technology is increasing rapidly across surgical specialities, yet there is no consensus for the term ‘digital surgery’. This is critical as digital health technologies present technical, governance, and legal challenges which are unique to the surgeon and surgical patient. We aim to define the term digital surgery and the ethical issues surrounding its clinical application, and to identify barriers and research goals for future practice. 38 international experts, across the fields of surgery, AI, industry, law, ethics and policy, participated in a four-round Delphi exercise. Issues were generated by an expert panel and public panel through a scoping questionnaire around key themes identified from the literature and voted upon in two subsequent questionnaire rounds. Consensus was defined if >70% of the panel deemed the statement important and <30% unimportant. A final online meeting was held to discuss consensus statements. The definition of digital surgery as the use of technology for the enhancement of preoperative planning, surgical performance, therapeutic support, or training, to improve outcomes and reduce harm achieved 100% consensus agreement. We highlight key ethical issues concerning data, privacy, confidentiality and public trust, consent, law, litigation and liability, and commercial partnerships within digital surgery and identify barriers and research goals for future practice. Developers and users of digital surgery must not only have an awareness of the ethical issues surrounding digital applications in healthcare, but also the ethical considerations unique to digital surgery. Future research into these issues must involve all digital surgery stakeholders including patients.

Machine learning for technical skill assessment in surgery: a systematic review

Accurate and objective performance assessment is essential for both trainees and certified surgeons. However, existing methods can be time consuming, labor intensive, and subject to bias. Machine learning (ML) has the potential to provide rapid, automated, and reproducible feedback without the need for expert reviewers. We aimed to systematically review the literature and determine the ML techniques used for technical surgical skill assessment and identify challenges and barriers in the field. A systematic literature search, in accordance with the PRISMA statement, was performed to identify studies detailing the use of ML for technical skill assessment in surgery. Of the 1896 studies that were retrieved, 66 studies were included. The most common ML methods used were Hidden Markov Models (HMM, 14/66), Support Vector Machines (SVM, 17/66), and Artificial Neural Networks (ANN, 17/66). 40/66 studies used kinematic data, 19/66 used video or image data, and 7/66 used both. Studies assessed the performance of benchtop tasks (48/66), simulator tasks (10/66), and real-life surgery (8/66). Accuracy rates of over 80% were achieved, although tasks and participants varied between studies. Barriers to progress in the field included a focus on basic tasks, lack of standardization between studies, and lack of datasets. ML has the potential to produce accurate and objective surgical skill assessment through the use of methods including HMM, SVM, and ANN. Future ML-based assessment tools should move beyond the assessment of basic tasks and towards real-life surgery and provide interpretable feedback with clinical value for the surgeon.

PROSPERO: CRD42020226071

An Observational Analysis of a Novel Digital Rectoscope

BACKGROUND

This is an analysis of the first 50 in-human uses of a novel digital rigid sigmoidoscope. The technology provides digital image capture, telemedicine capabilities, improved ergonomics, and the ability to biopsy under pneumorectum while maintaining the low cost of conventional rigid sigmoidoscopy. The primary outcome was adverse events, and the secondary outcome was diagnostic view.

PRELIMINARY RESULTS

Fifty patients underwent outpatient (n = 25) and surgical rectal assessment (n = 25), with a mean age of 60 years. This included 31 men and 19 women with 12 different clinical use indications. No adverse events were reported, and no defects were reported with the instrumentation. Satisfactory diagnoses were obtained in 48 (96%) of 50 uses, images were captured in 48 (96%) of 50 uses, and biopsies were successfully taken in 13 uses (26%). No adverse events were recorded. Independent reviewers of recorded videos agreed on the quality and diagnostic value of the images with a κ of 0.225 (95% CI, 0.144-0.305) when assessing whether the target pathology was adequately visualized.

IMPACT OF INNOVATION

The improved views afforded by digital rectoscopy facilitated a satisfactory clinical diagnosis in 96% of uses. The device was successfully deployed in the operating room and outpatients irrespective of bowel preparation method, where it has the potential to replace flexible sigmoidoscopy for specific use cases. The technology provides a high-quality image and video that can be securely recorded for documentation and medicolegal purposes with agreement between blinded users despite a lack of standardized training and heterogenous pathology. We perceive significant impact of this technology for the assessment of colorectal anastomoses, the office management of colitis, "watch and wait," and for diagnostic support in rectal cancer diagnosis. The technology has significant potential to facilitate proctoring and training, and it now requires prospective trials to validate its diagnostic accuracy against more costly flexible sigmoidoscopy systems.

The Ethical Digital Surgeon

This viewpoint explores the ethical and regulatory consequences of the digital transformation of the operating room. Surgical robotics is undergoing significant change and future advances will center around the capture and use of data. The consequences of creating this surgical data pipeline must be understood and digital surgical systems must prioritize the safeguarding of patient data. Moreover, data protection laws and frameworks must adapt to the changing nature of surgical data. Finally, digital surgeons must understand changing data legislation and best practice on data governance to act as guardians not only for their own but also for their patients’ data.

Abstract 271: High-throughput fecal metabolic profiling for the early detection of colorectal cancer using a direct mass spectrometry assay

Early stage diagnosis of colorectal cancer (CRC) is a key predictor of patient survival, highlighting the need for accurate diagnostic biomarkers. Laser Assisted - Rapid Evaporative Ionization Mass Spectrometry (LA-REIMS) demonstrates potential for direct from sample metabolic profiling of feces. Here, we present an optimized LA-REIMS approach for fecal metabolomic analysis in CRC for the first time.

A prospective, observational cohort biomarker discovery study was performed at an NHS hospital trust in the UK. Patients referred through the national two week wait cancer pathway were prospectively recruited. The primary outcome was to differentiate between adenomas or CRC and non-disease controls, the secondary outcome was to compare LA-REIMS to fecal immunochemical testing (FIT) against the gold-standard of colonoscopy or CT colonography. Those under the age of 18, pregnant, or unable to undergo colonic investigation were excluded. Fecal samples were analyzed using FIT (Kyowa Medex Co Ltd, Japan), with a detection limit of 7µg haemoglobin/g feces considered a positive result, as well as a LA-REIMS setup (Xevo G2-S QTof (Waters Corporation)), with optimized laser and instrumentation parameters (improved signal-to-noise and reduced carry-over between samples). After pre-processing, univariate and multivariate statistics were carried out in MetaboAnalyst 4.0. Random forest classification (RFC) with leave one out cross-validation (LOOCV) was performed.244 subjects (120 females, mean age 67.5 (range 21-93)) were included, of which n=135 were non-disease controls, n=82 adenoma patients, and n=27 CRC patients. Partial least square-discriminant analysis (PLS-DA) demonstrated a distinction between control vs CRC (Q2= 0.60087, R2= 0.89376). RFC with LOOCV for cancer vs control showed a sensitivity of 34.6% and specificity of 99.2% compared to 81.8% sensitivity and 87.2% specificity with FIT. PLS-DA of control vs adenoma (Q2= 0.64284, R2= 0.8898) demonstrated good separation. RFC with LOOCV for adenoma vs control had a sensitivity of 61.0 % and specificity of 94.7% compared to 33.8 % sensitivity and 87.2% specificity with FIT. Univariate analysis identified a feature tentatively assigned to the glycerolipid class (area under the receiver operating characteristic curve (AUROC) 0.986 (CI=0.957-1) to be more abundant in CRC vs control (false discovery rate (FDR) corrected p&lt;0.001). A tentatively assigned organic acid (AUC 0.916, CI=0.868-0.953) was associated with control (FDR corrected p&lt;0.001). Multiple features in the mass-to-charge ratio (m/z) range 200-400 were found to be significantly different between control vs adenoma. Annotations of the features are underway using liquid chromatography - MS/MS and spiked standards. LA-REIMS allows direct from sample metabolite profiling of feces and has applications as a novel screening tool for the early detection of CRC.

Citation Format: Petra Paizs, Monika Widlak, Alvaro Perdones-Montero, Maria Sani, Lauren Ford, James L. Alexander, Simon Cameron, Ramesh Arasaradnam, James M. Kinross, Zoltan Takats. High-throughput fecal metabolic profiling for the early detection of colorectal cancer using a direct mass spectrometry assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 271.

Enhanced triacylglycerol catabolism by carboxylesterase 1 promotes aggressive colorectal carcinoma

The ability to adapt to low-nutrient microenvironments is essential for tumor cell survival and progression in solid cancers, such as colorectal carcinoma (CRC). Signaling by the NF-κB transcription factor pathway associates with advanced disease stages and shorter survival in patients with CRC. NF-κB has been shown to drive tumor-promoting inflammation, cancer cell survival, and intestinal epithelial cell (IEC) dedifferentiation in mouse models of CRC. However, whether NF-κB affects the metabolic adaptations that fuel aggressive disease in patients with CRC is unknown. Here, we identified carboxylesterase 1 (CES1) as an essential NF-κB-regulated lipase linking obesity-associated inflammation with fat metabolism and adaptation to energy stress in aggressive CRC. CES1 promoted CRC cell survival via cell-autonomous mechanisms that fuel fatty acid oxidation (FAO) and prevent the toxic build-up of triacylglycerols. We found that elevated CES1 expression correlated with worse outcomes in overweight patients with CRC. Accordingly, NF-κB drove CES1 expression in CRC consensus molecular subtype 4 (CMS4), which is associated with obesity, stemness, and inflammation. CES1 was also upregulated by gene amplifications of its transcriptional regulator HNF4A in CMS2 tumors, reinforcing its clinical relevance as a driver of CRC. This subtype-based distribution and unfavorable prognostic correlation distinguished CES1 from other intracellular triacylglycerol lipases and suggest CES1 could provide a route to treat aggressive CRC.

Accurate early-stage colorectal cancer detection through analysis of cell-free circulating tumor DNA (ctDNA) methylation patterns

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Background: Colorectal cancer (CRC) screening programs suffer from poor uptake and biomarkers have limited diagnostic accuracy. The measurement of the methylation status of tumor-derived cell-free DNA in plasma may address these challenges. We used a targeted methylation panel, tumor-derived signal deduction and machine learning algorithm to refine a blood test for the detection of early-stage CRC. Methods: This was a prospective, international multicenter observational cohort study. Plasma samples were collected either prior to a scheduled colonoscopy as part of standard colorectal cancer screening or prior to colonic surgery for primary CRC. Differentially methylated regions (DMRs) were initially selected by analyzing CRC and control tissue samples with whole genome bisulfite sequencing. A targeted sequencing assay was designed to capture these DMRs in plasma ctDNA. Individual sequencing reads were evaluated for cancer-specific methylation signal and scores calculated for each DMR in a sample. A panel of methylation scores originating from 203 DMRs was used in a prediction model building and validated in a test cohort of patients. Results: Calculated scores were used to train a machine learning model on 68 ctDNA samples from 18 early stage (I-II) and 16 late-stage (III-IV) CRC patients and 34 age, BMI, gender and country of origin matched neoplasia-free controls (median age 63 [50-74], mean BMI 27 [19.5-37], female 50%, Spanish and Ukrainian population, distal cancers 50%). This model was then applied to an independent set of subjects from Spanish, Ukraine and Germany, including 36 stage I-IV cancer patients (median age 61.5 [55-82], BMI 28 [16-39], female 47%, 42% of the tumors were distal) and 159 age and sex matched controls. 87 of the control patients had a negative colonoscopy finding (cNEG), 19 had hyperplastic polyps (HP), 37 had small non-advanced adenomas (NAA) and 16 were diagnosed with other benign gastrointestinal diseases (GID). The model correctly classified 92% (33/36) of CRC patients. Sensitivity per cancer stage ranged from 83% (5/6) for stage I, 92% (11/12) for stage II, 92% (12/13) for stage III to 100% (5/5) for stage IV. Specificity of the model was 97% (154/159), with 100% (37/37) NAA, 94% (15/16) GID, 95% (18/19) HP and 97% cNEG patients correctly identified. Lesion location, gender, BMI, age and country of origin were not significantly correlated to prediction outcome. Conclusions: Methylation sequencing data analyzed using read-wise scoring approach combined with a machine-learning algorithm is highly diagnostic for early-stage (I-II) CRCs (89% sensitivity at 97% specificity). This method could serve as the basis for a highly accurate and minimally invasive blood-based CRC screening test with significant implications for the clinical utility of ctDNA in early-stage cancer detection.

Investigating the Ethical and Data Governance Issues of Artificial Intelligence in Surgery: Protocol for a Delphi Study

BACKGROUND

The rapid uptake of digital technology into the operating room has the potential to improve patient outcomes, increase efficiency of the use of operating rooms, and allow surgeons to progress quickly up learning curves. These technologies are, however, dependent on huge amounts of data, and the consequences of their mismanagement are significant. While the field of artificial intelligence ethics is able to provide a broad framework for those designing and implementing these technologies into the operating room, there is a need to determine and address the ethical and data governance challenges of using digital technology in this unique environment.

OBJECTIVE

The objectives of this study are to define the term digital surgery and gain expert consensus on the key ethical and data governance issues, barriers, and future research goals of the use of artificial intelligence in surgery.

METHODS

Experts from the fields of surgery, ethics and law, policy, artificial intelligence, and industry will be invited to participate in a 4-round consensus Delphi exercise. In the first round, participants will supply free-text responses across 4 key domains: ethics, data governance, barriers, and future research goals. They will also be asked to provide their understanding of the term digital surgery. In subsequent rounds, statements will be grouped, and participants will be asked to rate the importance of each issue on a 9-point Likert scale ranging from 1 (not at all important) to 9 (critically important). Consensus is defined a priori as a score of 7 to 9 by 70% of respondents and 1 to 3 by less than 30% of respondents. A final online meeting round will be held to discuss inclusion of statements and draft a consensus document.

RESULTS

Full ethical approval has been obtained for the study by the local research ethics committee at Imperial College, London (20IC6136). We anticipate round 1 to commence in January 2021.

CONCLUSIONS

The results of this study will define the term digital surgery, identify the key issues and barriers, and shape future research in this area.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/26552.

Insights from a global snapshot of the change in elective colorectal practice due to the COVID-19 pandemic

BACKGROUND

There is a need to understand the impact of COVID-19 on colorectal cancer care globally and determine drivers of variation.

OBJECTIVE

To evaluate COVID-19 impact on colorectal cancer services globally and identify predictors for behaviour change.

DESIGN

An online survey of colorectal cancer service change globally in May and June 2020.

PARTICIPANTS

Attending or consultant surgeons involved in the care of patients with colorectal cancer.

MAIN OUTCOME MEASURES

Changes in the delivery of diagnostics (diagnostic endoscopy), imaging for staging, therapeutics and surgical technique in the management of colorectal cancer. Predictors of change included increased hospital bed stress, critical care bed stress, mortality and world region.

RESULTS

191 responses were included from surgeons in 159 centers across 46 countries, demonstrating widespread service reduction with global variation. Diagnostic endoscopy was reduced in 93% of responses, even with low hospital stress and mortality; whilst rising critical care bed stress triggered complete cessation (p = 0.02). Availability of CT and MRI fell by 40-41%, with MRI significantly reduced with high hospital stress. Neoadjuvant therapy use in rectal cancer changed in 48% of responses, where centers which had ceased surgery increased its use (62 vs 30%, p = 0.04) as did those with extended delays to surgery (p<0.001). High hospital and critical care bed stresses were associated with surgeons forming more stomas (p<0.04), using more experienced operators (p<0.003) and decreased laparoscopy use (critical care bed stress only, p<0.001). Patients were also more actively prioritized for resection, with increased importance of co-morbidities and ICU need.

CONCLUSIONS

The COVID-19 pandemic was associated with severe restrictions in the availability of colorectal cancer services on a global scale, with significant variation in behaviours which cannot be fully accounted for by hospital burden or mortality.

Uptake and accessibility of surgical robotics in England

BACKGROUND

The distribution, utilisation and accessibility of surgical robotics in England is unknown.

METHODS

A nationwide Freedom of Information (FOI) request was sent to all acute National Health Service (NHS) trusts. Accessibility was assessed for 32 843 Lower Super Output Areas in England.

RESULTS

All 149 acute NHS trusts responded to the FOI request. Sixty-one robots are distributed between 48 trusts. The number of robots and robotic procedures has increased annually. Urological procedures comprise 84.2% of robotic procedures. Procedure volume varies between robotic centres ranging from 1 to 683 in 2018. Over 2.4 million people have a travel time of over 1 hour to their nearest robotic centre.

DISCUSSION

National accessibility to robotic services and case volumes are variable and does not represent good value for the NHS. A national robotic surgery registry could improve the quality of robotic surgery and is needed to dynamically assess national provision of this technology.

International Cancer Microbiome Consortium consensus statement on the role of the human microbiome in carcinogenesis

OBJECTIVE

In this consensus statement, an international panel of experts deliver their opinions on key questions regarding the contribution of the human microbiome to carcinogenesis.

DESIGN

International experts in oncology and/or microbiome research were approached by personal communication to form a panel. A structured, iterative, methodology based around a 1-day roundtable discussion was employed to derive expert consensus on key questions in microbiome-oncology research.

RESULTS

Some 18 experts convened for the roundtable discussion and five key questions were identified regarding: (1) the relevance of dysbiosis/an altered gut microbiome to carcinogenesis; (2) potential mechanisms of microbiota-induced carcinogenesis; (3) conceptual frameworks describing how the human microbiome may drive carcinogenesis; (4) causation versus association; and (5) future directions for research in the field.The panel considered that, despite mechanistic and supporting evidence from animal and human studies, there is currently no direct evidence that the human commensal microbiome is a key determinant in the aetiopathogenesis of cancer. The panel cited the lack of large longitudinal, cohort studies as a principal deciding factor and agreed that this should be a future research priority. However, while acknowledging gaps in the evidence, expert opinion was that the microbiome, alongside environmental factors and an epigenetically/genetically vulnerable host, represents one apex of a tripartite, multidirectional interactome that drives carcinogenesis.

CONCLUSION

Data from longitudinal cohort studies are needed to confirm the role of the human microbiome as a key driver in the aetiopathogenesis of cancer.

Abstract 4536: Rapid evaporative ionization mass spectrometry (REIMS) analysis of the mucosal lipidome has a high diagnostic accuracy for adenomas and early colorectal cancer

Introduction

The aim of this study was to determine the diagnostic accuracy of REIMS for dysplasia in human adenomas and early colorectal cancer and to determine changes in mucosal lipid chemistry during cancer initiation. Moreover, we attempted to develop a proof of concept first in man study of a novel REIMS-based endoscope for in-vivo chemical phenotyping of adenomas based on the real time analysis of phosphatidic acid (PA) and phosphatidylethanolamine (PE) metabolism.

Experimental procedure

A prospective, observational cross-sectional cohort study was performed in patients undergoing elective resection for colorectal cancer or colonoscopy at Imperial College London NHS Trust. Two tissue types were obtained - early colorectal cancer (defined as T1 or T2 according to TNMv6 criteria) and adenomatous polyps. Patients with familial adenomatous polyposis, inflammatory bowel disease or hereditary non-polyposis colon cancer were excluded. Specimens were analyzed ex-vivo using a modified electro-surgical hand piece with the aerosol aspirated into a Xevo G2-S QTof mass spectrometer (Waters Corporation). Multivariate analyses were used to create models which underwent cross-validation using SIMCA (V14, Umetrics, Sweden). Characteristic lipid species were identified using univariate statistics in R Studio (V1.0.44) and Metlin. An endoscopic set up was created using a standard endoscope for proof of concept.

Summary of data

19 patients (12:7 F:M) were included with a median age of 74 (range 50-92). Six patients had T1/2 adenocarcinoma and 13 had adenomatous polyps. REIMS was able to accurately distinguish the presence of low grade dysplasia (LGD) vs high grade dysplasia (HGD) in adenomatous polyps (sensitivity 95.0%, specificity 100%). Phosphatidic acids (PA) 38:2 and 38:1 were more abundant in high vs low grade dysplasia (p=0.003). REIMS was also able to identify adenomatous polyps from early cancer (sensitivity 100%, specificity 96.3%). Phosphatidylethanolamine (PE) 36:1, phosphatidic acid (PA) 38:1, glucosylceramide (Glc-Cer) 30:1 and ceramide phosphoethanolamines (PE-Cer) d16:1(4E)/20:0 and d14:1(4E)/22:0 were associated with early cancer formation rather than adenomas (p&lt;0.001, p&lt;0.001, p=0.03, p=0.04 respectively). Endoscopic REIMS was successfully deployed in-vivo in six patients undergoing polypectomy. Spectra with good signal to noise ratio were acquired and the technology was able to correctly stratify adenomas.

Conclusion

Dysplastic adenomas exhibit mucosal lipid chemistry that is discrete from early colorectal cancer. PA, PE and Glc-Cer have potential use as diagnostic biomarkers. First in man studies of the endoscopic application of REIMS suggest it could serve as a real-time tool for early cancer detection based on in vivo analysis of the mucosal lipidome.

Citation Format: Petra Paizs, Eftychios Manoli, Sam E. Mason, James L. Alexander, Zsolt Bodai, Emma White, Afeez Adebesin, Jonathan Hoare, Robert Goldin, Ara W. Darzi, James M. Kinross, Zoltan Takats. Rapid evaporative ionization mass spectrometry (REIMS) analysis of the mucosal lipidome has a high diagnostic accuracy for adenomas and early colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4536.

Goblet cell carcinomas of the appendix: rare but aggressive neoplasms with challenging management

Goblet cell carcinomas (GCC) are a rare, aggressive sub-type of appendiceal tumours with neuroendocrine features, and controversy exists with regards to therapeutic strategy. We undertook a retrospective review of GCC patients surgically treated at two tertiary referral centres. Clinical and histopathological data were extracted from a prospectively maintained database. Survival analyses utilised Kaplan-Meier methodology. Twenty-one patients were identified (9 females). Median age at diagnosis was 55 years (range 32-77). There were 3, 6 and 9 grade 1, 2 and 3 tumours, respectively. One, 10, 5 and 5 patients had stage I, II, III and IV disease at diagnosis, respectively. There were 8, 10 and 3 Tang class A, B and C tumours, respectively. Index operation was appendectomy (n = 12), right hemicolectomy (n = 6) or resections including appendix/right colon, omentum and the gynaecological system (n = 3). Eight patients underwent completion right hemicolectomy. Surgery for recurrence included small bowel resection (n = 2), debulking with peritonectomy and heated intraperitoneal chemotherapy, and hysterectomy and bilateral salpingo-oophorectomy (all n = 1). Median follow-up was 30 months (range 2.5-123). One-, 3- and 5-year OS was 79.4, 60 and 60%, respectively. Mean OS (1-, 3-, and 5-year OS) for Tang class A, B and C tumours were 73.1 months (85.7, 85.7, 51.4%), 83.7 months (all 66.7%) and 28.5 months (66.7, 66.7%, not reached), respectively. Chromogranin A/B and ⁶⁸Ga-DOTATATE PET/CT were not useful in follow-up, but CEA, CA 19-9, CA 125 and ¹⁸F-FDG PET/CT identified tumour recurrence. GCC must be clearly discriminated from relatively indolent appendiceal neuroendocrine neoplasms. ¹⁸F-FDG PET/CT and CEA/CA19-9/CA 125 are useful in detecting recurrence of GCC.

Highlights from the Inaugural International Cancer Microbiome Consortium Meeting (ICMC), 5-6 September 2017, London, UK

The International Cancer Microbiome Consortium (ICMC) is a recently launched collaborative between academics and academic-clinicians that aims to promote microbiome research within the field of oncology, establish expert consensus and deliver education for academics and clinicians. The inaugural two-day meeting was held at the Royal Society of Medicine (RSM), London, UK, 5–6 September 2017. Microbiome and cancer experts from around the world first delivered a series of talks during an educational day and then sat for a day of roundtable discussion to debate key topics in microbiome-cancer research.

Talks delivered during the educational day covered a broad range of microbiome-related topics. The potential role of the microbiome in the pathogenesis of colorectal cancer was discussed and debated in detail with experts highlighting the latest data in animal models and humans and addressing the question of causation versus association. The impact of the microbiota on other cancers—such as lung and urogenital tract—was also discussed. The microbiome represents a novel target for therapeutic manipulation in cancer and a number of talks explored how this might be realised through diet, faecal microbiota transplant and chemotherapeutics.

On the second day, experts debated pre-agreed topics with the aim of producing a consensus statement with a focus on the current state of our knowledge and key gaps for further development. The panel debated the notion of a ‘healthy’ microbiome and, in turn, the concept of dysbiosis in cancer. The mechanisms of microbiota-induced carcinogenesis were discussed in detail and our current conceptual models were assessed. Experts also considered co-factors in microbiome-induced carcinogenesis to conclude that the tripartite ‘interactome’ between genetically vulnerable host, environment and the microbiome is central to our current understanding. To conclude, the roundtable discussed how the microbiome may be exploited for therapeutic benefit in cancer and the safety implications of performing such research in oncology patients.

Longitudinal analysis of serum oxylipin profile as a novel descriptor of the inflammatory response to surgery

BACKGROUND

Oxylipins are potent lipid mediators demonstrated to initiate and regulate inflammation yet little is known regarding their involvement in the response to surgical trauma. As key modulators of the inflammatory response, oxylipins have the potential to provide novel insights into the physiological response to surgery and the pathophysiology of post-operative complications. We aimed to investigate the effects of major surgery on longitudinal oxylipin profile.

METHODS

Adults patients undergoing elective laparoscopic or open colorectal resections were included. Primary outcomes were serum oxylipin profile quantified by ultra high-performance liquid chromatography-mass spectrometry, serum white cell count and C-reactive protein concentration. Serum samples were taken at three time-points: pre-operative (day zero), early post-operative (day one) and late post-operative (day four/five).

RESULTS

Some 55 patients were included, of which 33 (60%) underwent surgery that was completed laparoscopically. Pre-operative oxylipin profiles were characterised by marked heterogeneity but surgery induced a common shift resulting in more homogeneity at the early post-operative time-point. By the late post-operative phase, oxylipin profiles were again highly variable. This evolution was driven by time-dependent changes in specific oxylipins. Notably, the levels of several oxylipins with anti-inflammatory properties (15-HETE and four regioisomers of DHET) were reduced at the early post-operative point before returning to baseline by the late post-operative period. In addition, levels of the pro-inflammatory 11-HETE rose in the early post-operative phase while levels of anti-thrombotic mediators (9-HODE and 13-HODE) fell; concentrations of all three oxylipins then remained fairly static from early to late post-operative phases. Compared to those undergoing laparoscopic surgery, patients undergoing open surgery had lower levels of some anti-inflammatory oxylipins (8,9-DHET and 17-HDoHE) in addition to reduced concentrations of anti-thrombotic mediators (9-HODE and 13-HODE) with increased concentration of their pro-thrombotic counterpart (TxB2).

CONCLUSIONS

Serum oxylipin profile is modified by surgical intervention and may even be sensitive to the degree of surgical trauma and therefore represents a novel descriptor of the surgical systemic inflammatory response.

Postoperative hypothermia and surgical site infection following peritoneal insufflation with warm, humidified carbon dioxide during laparoscopic colorectal surgery: a cohort study with cost-effectiveness analysis

Background

Surgical Site Infection (SSI) occurs in 9 % of laparoscopic colorectal surgery. Warming and humidifying carbon dioxide (CO₂) used for peritoneal insufflation may protect against SSI by avoiding postoperative hypothermia (itself a risk factor for SSI). This study aimed to assess the impact of CO₂ conditioning on postoperative hypothermia and SSI and to perform a cost-effectiveness analysis.

Methods

A retrospective cohort study of patients undergoing elective laparoscopic colorectal resection was performed at a single UK specialist centre. The control group (n = 123) received peritoneal insufflation with room temperature, dry CO₂, whereas the intervention group (n = 123) received warm, humidified CO₂ (using HumiGard™, Fisher & Paykel Healthcare). The outcomes were postoperative hypothermia, SSI and costs. Multivariate analysis was performed.

Results

A total of 246 patients were included in the study. The mean age was 68 (20–87) and mean BMI 28 (15–51). The primary diagnosis was cancer (n = 173), and there were no baseline differences between the groups. CO₂ conditioning significantly decreased the incidence of postoperative hypothermia (odds ratio 0.10, 95 % CI 0.04–0.23), with hypothermic patients found to be at increased risk of SSI (odds ratio 4.0, 95 % CI 1.25–12.9). Use of conditioned CO₂ significantly decreased the incidence of SSI by 66 % (p = 0.04). The intervention group incurred costs of £155 less per patient. The incremental cost-effectiveness ratio was negative.

Conclusion

CO₂ conditioning during laparoscopic colorectal surgery is a safe, feasible and a cost-effective intervention. It improves the quality of surgical care relating to SSI and postoperative hypothermia.

Risk stratification by the Appendicitis Inflammatory Response score to guide decision-making in patients with suspected appendicitis

BACKGROUND

Current management of suspected appendicitis is hampered by the overadmission of patients with non-specific abdominal pain and a significant negative exploration rate. The potential benefits of risk stratification by the Appendicitis Inflammatory Response (AIR) score to guide clinical decision-making were assessed.

METHODS

During this 50-week prospective observational study at one institution, the AIR score was calculated for all patients admitted with suspected appendicitis. Appendicitis was diagnosed by histological examination, and patients were classified as having non-appendicitis pain if histological findings were negative or surgery was not performed. The diagnostic performance of the AIR score and the potential for risk stratification to reduce admissions, optimize imaging and prevent unnecessary explorations were quantified.

RESULTS

A total of 464 patients were included, of whom 210 (63·3 per cent) with non-appendicitis pain were correctly classified as low risk. However, 13 low-risk patients had appendicitis. Low-risk patients accounted for 48·1 per cent of admissions (223 of 464), 57 per cent of negative explorations (48 of 84) and 50·7 per cent of imaging requests (149 of 294). An AIR score of 5 or more (intermediate and high risk) had high sensitivity for all severities of appendicitis (90 per cent) and also for advanced appendicitis (98 per cent). An AIR score of 9 or more (high risk) was very specific (97 per cent) for appendicitis, and the majority of patients with appendicitis in the high-risk group (21 of 30, 70 per cent) had perforation or gangrene. Ultrasound imaging could not exclude appendicitis in low-risk patients (negative likelihood ratio (LR) 1·0) but could rule-in the diagnosis in intermediate-risk patients (positive LR 10·2). CT could exclude appendicitis in low-risk patients (negative LR 0·0) and rule-in appendicitis in the intermediate group (positive LR 10·9).

CONCLUSION

Risk stratification of patients with suspected appendicitis by the AIR score could guide decision-making to reduce admissions, optimize utility of diagnostic imaging and prevent negative explorations.

Rapid evaporative ionization mass spectrometry imaging platform for direct mapping from bulk tissue and bacterial growth media

Rapid evaporative ionization mass spectrometry (REIMS) technology allows real time intraoperative tissue classification and the characterization and identification of microorganisms. In order to create spectral libraries for training the classification models, reference data need to be acquired in large quantities as classification accuracy generally improves as a function of number of training samples. In this study, we present an automated high-throughput method for collecting REIMS data from heterogeneous organic tissue. The underlying instrumentation consists of a 2D stage with an additional high-precision z-axis actuator that is equipped with an electrosurgical diathermy-based sampling probe. The approach was validated using samples of human liver with metastases and bacterial strains, cultured on solid medium, belonging to the species P. aeruginosa, B. subtilis, and S. aureus. For both sample types, spatially resolved spectral information was obtained that resulted in clearly distinguishable multivariate clustering between the healthy/cancerous liver tissues and between the bacterial species.

1H NMR global metabolic phenotyping of acute pancreatitis in the emergency unit

We have investigated the urinary and plasma metabolic phenotype of acute pancreatitis (AP) patients presenting to the emergency room at a single center London teaching hospital with acute abdominal pain using (1)H NMR spectroscopy and multivariate modeling. Patients were allocated to either the AP (n = 15) or non-AP patients group (all other causes of abdominal pain, n = 21) on the basis of the national guidelines. Patients were assessed for three clinical outcomes: (1) diagnosis of AP, (2) etiology of AP caused by alcohol consumption and cholelithiasis, and (3) AP severity based on the Glasgow score. Samples from AP patients were characterized by high levels of urinary ketone bodies, glucose, plasma choline and lipid, and relatively low levels of urinary hippurate, creatine and plasma-branched chain amino acids. AP could be reliably identified with a high degree of sensitivity and specificity (OPLS-DA model R(2) = 0.76 and Q(2)Y = 0.59) using panel of discriminatory biomarkers consisting of guanine, hippurate and creatine (urine), and valine, alanine and lipoproteins (plasma). Metabolic phenotyping was also able to distinguish between cholelithiasis and colonic inflammation among the heterogeneous non-AP group. This work has demonstrated that combinatorial biomarkers have a strong diagnostic and prognostic potential in AP with relevance to clinical decision making in the emergency unit.

Novel data processing and image co-registration algorithm for region-specific lipid profiling in colorectal cancer tissue using DESI imaging mass spectrometry

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Background: Imaging mass spectrometry (iMS) is a promising technique for cancer biomarker discovery. Clinical translation of iMS requires advanced data treatment methods and efficient co-registration of histology and iMS imaging modalities. In this study desorption electrospray ionisation (DESI) iMS has been used to address four aims: 1. To develop a data processing workflow to address current limitations; 2. To design an interactive software platform for image co-registration; 3. To investigate region-specific lipid biochemistry in colorectal cancer (CRC) tissue using the strategy outlined in aims 1-2; 4.To introduce an automated tissue recognition system based on multivariate molecular ion patterns (MIPs). Methods: Fresh CRC tissue sections (n=49) were subjected to DESI-iMS using a Thermo Exactive mass spectrometer coupled with a DESI ion source. Mass spectra were collected in the range m/z = 200-1000. Sections were then H&E stained and scanned at high resolution. DESI-iMS data pre-processing involved peak detection, removal of noise/solvent related peaks and variance stabilising normalisation. An interactive image co-registration interface was developed using a feature-based image alignment algorithm for precise exploration of tissue region-specific biochemistry. A Recursive Maximum Margin Criterion (RMMC) algorithm was introduced for improved extraction of tissue specific MIPs. Results: CRC DESI-iMS profiles consisted mainly of complex lipids including phosphatidyl-inositols, phosphatidyl-serines, and phosphatidyl-ethanolamine plasmalogens. Different histological tissue regions showed characteristic lipid profiles. An automated tissue recognition system using multivariate MIPs derived by the proposed RMMC approach demonstrated highly accurate (classification accuracy >98%) identification of pixels according to tissue type (cancer, healthy mucosa, smooth muscle, fibrous tissue, stroma). Conclusions: This workflow permits accurate tissue-specific lipidomic characterisation of the CRC tumor microenvironment and permits accurate reconstruction of different tissue types based on MIPs.

Metabolic phenotyping in clinical and surgical environments

Metabolic phenotyping involves the comprehensive analysis of biological fluids or tissue samples. This analysis allows biochemical classification of a person's physiological or pathological states that relate to disease diagnosis or prognosis at the individual level and to disease risk factors at the population level. These approaches are currently being implemented in hospital environments and in regional phenotyping centres worldwide. The ultimate aim of such work is to generate information on patient biology using techniques such as patient stratification to better inform clinicians on factors that will enhance diagnosis or the choice of therapy. There have been many reports of direct applications of metabolic phenotyping in a clinical setting.

Gut microbiome-host interactions in health and disease

The gut microbiome is the term given to describe the vast collection of symbiotic microorganisms in the human gastrointestinal system and their collective interacting genomes. Recent studies have suggested that the gut microbiome performs numerous important biochemical functions for the host, and disorders of the microbiome are associated with many and diverse human disease processes. Systems biology approaches based on next generation 'omics' technologies are now able to describe the gut microbiome at a detailed genetic and functional (transcriptomic, proteomic and metabolic) level, providing new insights into the importance of the gut microbiome in human health, and they are able to map microbiome variability between species, individuals and populations. This has established the importance of the gut microbiome in the disease pathogenesis for numerous systemic disease states, such as obesity and cardiovascular disease, and in intestinal conditions, such as inflammatory bowel disease. Thus, understanding microbiome activity is essential to the development of future personalized strategies of healthcare, as well as potentially providing new targets for drug development. Here, we review recent metagenomic and metabonomic approaches that have enabled advances in understanding gut microbiome activity in relation to human health, and gut microbial modulation for the treatment of disease. We also describe possible avenues of research in this rapidly growing field with respect to future personalized healthcare strategies.

Global metabolic phenotyping in an experimental laparotomy model of surgical trauma

Surgical trauma initiates a complex series of metabolic host responses designed to maintain homeostasis and ensure survival. (1)H NMR spectroscopy was applied to intraoperative urine and plasma samples as part of a strategy to analyze the metabolic response of Wistar rats to a laparotomy model. Spectral data were analyzed by multivariate statistical analysis. Principal component analysis (PCA) confirmed that surgical injury is responsible for the majority of the metabolic variability demonstrated between animals (R² Urine = 81.2% R² plasma = 80%). Further statistical analysis by orthogonal projection to latent structure discriminant analysis (OPLS-DA) allowed the identification of novel urinary metabolic markers of surgical trauma. Urinary levels of taurine, glucose, urea, creatine, allantoin, and trimethylamine-N-oxide (TMAO) were significantly increased after surgery whereas citrate and 2-oxoglutarate (2-OG) negatively correlated with the intraoperative state as did plasma levels of betaine and tyrosine. Plasma levels of lipoproteins such as VLDL and LDL also rose with the duration of surgery. Moreover, the microbial cometabolites 3-hydroxyphenylpropionate, phenylacetylglycine, and hippurate correlated with the surgical insult, indicating that the gut microbiota are highly sensitive to the global homeostatic state of the host. Metabonomic profiling provides a global overview of surgical trauma that has the potential to provide novel biomarkers for personalized surgical optimization and outcome prediction.