Is Robotic Surgery the Future for Resectable Esophageal Cancer?: A Systematic Literature Review of Oncological and Clinical Outcomes.

BACKGROUND: Radical esophagectomy for resectable esophageal cancer is a major surgical intervention, associated with considerable postoperative morbidity. The introduction of robotic surgical platforms in esophagectomy may enhance advantages of minimally invasive surgery enabled by laparoscopy and thoracoscopy, including reduced postoperative pain and pulmonary complications. This systematic review aims to assess the clinical and oncological benefits of robot-assisted esophagectomy. METHODS: A systematic literature search of the MEDLINE (PubMed), Embase and Cochrane databases was performed for studies published up to 1 August 2023. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocols and was registered in the PROSPERO database (CRD42022370983). Clinical and oncological outcomes data were extracted following full-text review of eligible studies. RESULTS: A total of 113 studies (n = 14,701 patients, n = 2455 female) were included. The majority of the studies were retrospective in nature (n = 89, 79%), and cohort studies were the most common type of study design (n = 88, 79%). The median number of patients per study was 54. Sixty-three studies reported using a robotic surgical platform for both the abdominal and thoracic phases of the procedure. The weighted mean incidence of postoperative pneumonia was 11%, anastomotic leak 10%, total length of hospitalisation 15.2 days, and a resection margin clear of the tumour was achieved in 95% of cases. CONCLUSIONS: There are numerous reported advantages of robot-assisted surgery for resectable esophageal cancer. A correlation between procedural volume and improvements in outcomes with robotic esophagectomy has also been identified. Multicentre comparative clinical studies are essential to identify the true objective benefit on outcomes compared with conventional surgical approaches before robotic surgery is accepted as standard of practice.

Circumferential resection margin rates in esophageal cancer resection- oncological equivalency and comparable clinical outcomes between open versus minimally invasive techniques: A retrospective cohort study.

BACKGROUND: Radical surgery for esophageal cancer requires macroscopic and microscopic clearance of all malignant tissue. A critical element of the procedure is achieving a negative circumferential margin (CRM) to minimize local recurrence. The utility of minimally invasive surgery poses challenges in replicating techniques developed in open surgery, particularly for hiatal dissection in esophago-gastrectomy. In this study, the technical approach and clinical and oncological outcomes for open and laparoscopic esophago-gastrectomy are described with particular reference to CRM involvement. MATERIALS AND METHODS: This cohort study included all patients undergoing either open or laparoscopic esophago-gastrectomy between January 2004 to June 2022 in a single tertiary center. A standard surgical technique for hiatal dissection of the esophago-gastric junction developed in open surgery was adapted for a laparoscopic approach. Clinical parameters, length of stay (LOS), post-operative complications and mortality data were collected and analyzed by a Mann-Whitney U or Fisher's exact method. RESULTS: Overall 447 patients underwent an esophago-gastrectomy in the study with 219 open and 228 laparoscopic procedures. The CRM involvement was 18.8% in open surgery and 13.6% in laparoscopic surgery. The 90-day-mortality for open surgery was 4.1% compared with 2.2% for laparoscopic procedures. Median Intensive care unit (ITU), inpatient LOS and 30-day readmission rates were shorter for laparoscopic compared with open esophago-gastrectomy (ITU: 5 versus 8 days, P=0.0004; LOS: 14 versus 20 days, P=0.022; 30-day re-admission 7.46% versus 10.50%). Post-operative complication rates were comparable across both cohorts. The rates of starting adjuvant chemotherapy were 51.8% after open and 74.4% in laparoscopic esophago-gastrectomy. CONCLUSION: This study presents a standardized surgical approach to hiatal dissection for esophageal cancer. We present equivalence between open and laparoscopic esophago-gastrectomy in clinical, oncological and survival outcomes with similar rates of CRM involvement. We also observe a significantly shorter hospital length of stay with the minimally invasive approach.

Complete Primary Pathological Response Following Neoadjuvant Treatment and Radical Resection for Pancreatic Ductal Adenocarcinoma.

INTRODUCTION: Neoadjuvant treatment (NAT) for borderline (BD) or locally advanced (LA) primary pancreatic cancer (PDAC) is now a widely adopted approach. We present a case series of patients who have achieved a complete pathological response of the primary tumour on final histology following neoadjuvant chemotherapy +/- chemoradiation and radical surgery. METHODS: Patients who underwent radical pancreatic resection following neoadjuvant treatment between March 2006 and March 2023 at a single institution were identified by retrospective case note review of a prospectively maintained database. RESULTS: Ten patients were identified to have a complete primary pathological response (ypT0) on postoperative histology. Before treatment, five patients were considered BD and five were LA according to National Comprehensive Cancer Network guidelines. All patients underwent staging Computed Tomography (CT) and nine underwent 18Fluorodeoxyglucose Positron Emission Tomography (18FDG-PET/CT) imaging, with a mean maximum standardized uptake value (SUVmax) of the primary lesion at 6.14 ± 1.98 units. All patients received neoadjuvant chemotherapy, and eight received further chemoradiotherapy prior to resection. Mean pre- and post-neoadjuvant treatment serum Ca19-9 was 148.0 ± 146.3 IU/L and 18.0 ± 18.7 IU/L, respectively (p = 0.01). The mean duration of NAT was 5.6 ± 1.7 months. The mean time from completion of NAT to surgery was 13.1 ± 8.3 weeks. The mean lymph node yield was 21.1 ± 10.4 nodes, with one patient found to have 1 lymph node involved. All resections were reported to be R0. The mean length of stay was 11.8 ± 6.2 days. At the time of analysis, one death was reported at 35 months postoperatively. Two cases of recurrence were reported at 16 months (surgical bed) and 33 months (pulmonary). All other patients remain alive and under active surveillance. The current overall survival is 26.6 ± 20.7 months and counting. CONCLUSIONS: Complete primary pathological response is uncommon but possible following neoadjuvant treatment in patients with PDAC. Further work to identify the common denominator within this unique cohort may lead to advances in the therapeutic approach and offer hope for patients diagnosed with borderline or locally advanced pancreatic ductal adenocarcinoma.

The Role of Mucin Expression in the Diagnosis of Oesophago-Gastric Cancer: A Systematic Literature Review.

Survival in oesophago-gastric cancer (OGC) is poor due to early diagnostic challenges. Non-invasive risk stratification may identify susceptible patients with pre-malignant or benign disease. Following diagnostic confirmation with endoscopic biopsy, early OGC may be treated sooner. Mucins are transmembrane glycoproteins implicated in OGC with potential use as biomarkers of malignant transformation. This systematic review defines the role of mucins in OGC diagnosis. A literature search of MEDLINE, Web of Science, Embase and Cochrane databases was performed following PRISMA protocols for studies published January 1960-December 2022. Demographic data and data on mucin sampling and analysis methods were extracted. The review included 124 studies (n = 11,386 patients). Gastric adenocarcinoma (GAc) was the commonest OG malignancy (n = 101) followed by oesophageal adenocarcinoma (OAc, n = 24) and squamous cell carcinoma (OSqCc, n = 10). Mucins MUC1, MUC2, MUC5AC and MUC6 were the most frequently implicated. High MUC1 expression correlated with poorer prognosis and metastases in OSqCc. MUC2 expression decreases during progression from healthy mucosa to OAc, causing reduced protection from gastric acid. MUC5AC was upregulated, and MUC6 downregulated in GAc. Mucin expression varies in OGC; changes may be epigenetic or mutational. Profiling upper GI mucin expression in OGC, with pre-malignant, benign and healthy controls may identify potential early diagnostic biomarkers.

Pathologic Lymph Node Regression After Neoadjuvant Chemotherapy Predicts Recurrence and Survival in Esophageal Adenocarcinoma: A Multicenter Study in the United Kingdom.

PURPOSE: There is limited evidence regarding the prognostic effects of pathologic lymph node (LN) regression after neoadjuvant chemotherapy for esophageal adenocarcinoma, and a definition of LN response is lacking. This study aimed to evaluate how LN regression influences survival after surgery for esophageal adenocarcinoma. METHODS: Multicenter cohort study of patients with esophageal adenocarcinoma treated with neoadjuvant chemotherapy followed by surgical resection at five high-volume centers in the United Kingdom. LNs retrieved at esophagectomy were examined for chemotherapy response and given a LN regression score (LNRS)-LNRS 1, complete response; 2, <10% residual tumor; 3, 10%-50% residual tumor; 4, >50% residual tumor; and 5, no response. Survival analysis was performed using Cox regression adjusting for confounders including primary tumor regression. The discriminatory ability of different LN response classifications to predict survival was evaluated using Akaike information criterion and Harrell C-index. RESULTS: In total, 17,930 LNs from 763 patients were examined. LN response classified as complete LN response (LNRS 1 ≥1 LN, no residual tumor in any LN; n = 62, 8.1%), partial LN response (LNRS 1-3 ≥1 LN, residual tumor ≥1 LN; n = 155, 20.3%), poor/no LN response (LNRS 4-5; n = 303, 39.7%), or LN negative (no tumor/regression; n = 243, 31.8%) demonstrated superior discriminatory ability. Mortality was reduced in patients with complete LN response (hazard ratio [HR], 0.35; 95% CI, 0.22 to 0.56), partial LN response (HR, 0.72; 95% CI, 0.57 to 0.93) or negative LNs (HR, 0.32; 95% CI, 0.25 to 0.42) compared with those with poor/no LN response. Primary tumor regression and LN regression were discordant in 165 patients (21.9%). CONCLUSION: Pathologic LN regression after neoadjuvant chemotherapy was a strong prognostic factor and provides important information beyond pathologic TNM staging and primary tumor regression grading. LN regression should be included as standard in the pathologic reporting of esophagectomy specimens.

Radiomic applications in upper gastrointestinal cancer surgery.

INTRODUCTION: Cross-sectional imaging plays an integral role in the management of upper gastrointestinal (UGI) cancer, from initial diagnosis and staging to determining appropriate treatment strategies. Subjective imaging interpretation has known limitations. The field of radiomics has evolved to extract quantitative data from medical imaging and relate these to biological processes. The key concept behind radiomics is that the high-throughput analysis of quantitative imaging features can provide predictive or prognostic information, with the goal of providing individualised care. OBJECTIVE: Radiomic studies have shown promising utility in upper gastrointestinal oncology, highlighting a potential role in determining stage of disease and degree of tumour differentiation and predicting recurrence-free survival. This narrative review aims to provide an insight into the concepts underpinning radiomics, as well as its potential applications for guiding treatment and surgical decision-making in upper gastrointestinal malignancy. CONCLUSION: Outcomes from studies to date have been promising; however, further standardisation and collaboration are required. Large prospective studies with external validation and evaluation of radiomic integration into clinical pathways are needed. Future research should now focus on translating the promising utility of radiomics into meaningful patient outcomes.

The Cancer Hub Approach for Upper Gastrointestinal Surgery During COVID-19 Pandemic: Outcomes from a UK Cancer Centre.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic caused unprecedented disruption to global healthcare delivery. In England, the majority of elective surgery was postponed or cancelled to increase intensive care capacity. Our unit instituted the 'RM Partners Cancer Hub' at the Royal Marsden Hospital in London, to deliver ongoing cancer surgery in a 'COVID-lite' setting. This article describes the operational set-up and outcomes for upper gastrointestinal (UGI) cancer resections performed during this period. METHODS: From April 2020 to April 2021, the Royal Marsden Hospital formed the RM Partners Cancer Hub. This approach was designed to coordinate resources and provide as much oncological treatment as feasible for patients across the RM Partners West London Cancer Alliance. A UGI surgical case prioritisation strategy, along with strict infection control pathways and pre-operative screening protocols, was adopted. RESULTS: A total of 231 patients underwent surgery for confirmed or suspected UGI cancer during the RM Partners Cancer Hub, with 213 completed resections and combined 90-day mortality rate of 3.5%. Good short-term survival outcomes were demonstrated with 2-year disease free survival (DFS) and overall survival (OS) for oesophageal (70.8% and 72.9%), gastric (66.7% and 83.3%) and pancreatic cancer resections (68.0% and 88.0%). One patient who developed perioperative COVID-19 during the RM Partners Cancer Hub operation made a full recovery with no lasting clinical sequelae. CONCLUSION: Our experience demonstrates that the RM Partners Cancer Hub approach is a safe strategy for continuing upper gastrointestinal (GI) resectional surgery during future periods of healthcare service disruption.

Neoadjuvant Chemotherapy-Chemoradiation for Borderline-Resectable Pancreatic Adenocarcinoma: A UK Tertiary Surgical Oncology Centre Series.

BACKGROUND: Patients with borderline-resectable pancreatic ductal adenocarcinoma (BR-PDAC) have historically poor survival, even after curative pancreatic resection and adjuvant chemotherapy. Emerging evidence suggests that neoadjuvant chemoradiation (NCR) improves R0 resection rates in BR-PDAC patients. We evaluated the R0 resection rate, disease-free survival (DFS) and overall survival (OS) in our patients who underwent NCR for BR-PDAC at our institution. METHODS: All patients who underwent NCR for BR-PDAC from January 2010 to March 2020 were included in the study. The patients received a variety of NCR regimens during the study period, and in patients with radiological evidence of tumour stability or regression, pancreatic resection was performed. The primary endpoint was the OS, and the secondary endpoints included patient morbidity, the R0 resection rate, histological parameters and the DFS. RESULTS: The study included 29 patients (16 men and 13 women), with a median age of 65 years (range 46-74 years). Of these 29 patients, 17 received FOLFIRINOX and 12 received gemcitabine (GEM)-based NCR regimens. All patients received chemoradiation at the end of chemotherapy (range 45-56 Gy). R0 resection was achieved in 75% of the patients, with a higher rate noted in the FOLFIRINOX group. The median DFS was 22 months for the whole cohort but higher in the FOLFIRINOX group (34 months). The median OS for the cohort was 29 months, with a higher median OS noted for the FOLFIRINOX cohort versus the GEM cohort (42 versus 28 months). CONCLUSION: NCR, particularly FOLFIRINOX-based treatment, for BR-PDAC results in higher rates of R0 resection and an increased median DFS and OS, supporting its continued use in this patient group.

Mini-mesohepatectomy for tumours at the hepatocaval confluence: A cases series and review of the literature.

Liver lesions located adjacent to the middle hepatic vein (MHV) at the hepatocaval confluence are rare. Mini-mesohepatectomy (MMH) allows resection of these lesions with preservation of liver parenchymal volume thus reducing the risk of post-hepatectomy liver failure (PHLF). We evaluated our experience of MMH at our institution and assessed post-operative complications, disease free survival (DFS) and overall survival (OS). All patients undergoing MMH at our institution were included in the study. Intra-operative parameters, histopathological data, DFS and OS were evaluated. 11 patients with colorectal liver metastasis underwent MMH between Jan 2012 and Dec 2020. MMH resulted in R0 resection rate in all patients with no PHLF. There were 1 post-operative bile leaks but no mortality following MMH. Median DFS was 13.5 months with OS being 60 months. MMH offers safe oncological resection of lesions at the MHV at the hepatocaval confluence and should be considered in patients presenting with such lesions.

The Diagnostic Accuracy of 18 F-FGD-PET/CT for Cancer of the Gallbladder: A Retrospective Study.

Background Gallbladder cancer has a poor prognosis and imaging can have variable diagnostic accuracy. We assessed the ability of preoperative 18 F-fluorodeoxyglucose positron emission tomography computed tomography ( 18 F-FDG-PET/CT) imaging to predict a postoperative histological diagnosis of gallbladder cancer. Method A retrospective analysis was undertaken in a cohort of patients, who had suspected gallbladder cancer on cross-sectional imaging and that underwent preoperative FDG-PET/CT scan. The discriminatory power of FDG-PET/CT was determined in receiver operator characteristic (ROC) analysis and diagnostic accuracy parameters were estimated at different thresholds of maximum standard unit value (SUV max ) . Results Twenty-two patients were included in the study; 7 had malignant and 15 benign diagnoses. There was no statistically significant difference between the measured SUV max between the two groups ( p = 0.71). With an area under the curve of 0.486, the ROC curve did not indicate any discriminatory power of FDG-PET/CT at any potential threshold of SUV max. Conclusion This study indicates that the diagnosis of primary gallbladder cancer cannot be accurately confirmed with FDG PET/CT scanning.

Node negative duodenal adenocarcinoma is associated with long-term patient survival following pancreaticoduodenal resection.

BACKGROUND: Duodenal adenocarcinoma (DA) is a rare gastrointestinal malignancy. There is limited data reporting patient outcomes following radical pancreatic resection for DA. We assessed the disease-free (DFS) and overall survival (OS) in patients undergoing pancreaticoduodenectomy for DA in our institution. METHODS: We retrospectively analysed all patients undergoing pancreatic resection of DA at our institution between January 2009 and March 2020 inclusive. RESULTS: Ninteen patients underwent pancreatic resection at our institution for DA during the study period. The overall postoperative morbidity and mortality was 37% and 5%, respectively. Nine patients (47%) had no nodal involvement. Median follow up was 25 months (range 1-108 months). Median DFS for our whole cohort was 17 months but was significantly higher in patients with no nodal metastasis [p < 0.001]. Median OS was 9.5 months for the whole cohort but was significantly higher in the patients with no nodal metastasis (60 months) compared to those with nodal metastasis (17.5 months) [p < 0.003]. CONCLUSION: Improved DFS and OS for patients undergoing pancreaticoduodenectomy for DAs is associated with lymph node negative disease.

Effect of perioperative FLOT versus ECF/ECX on short-term outcomes after surgery for resectable oesophagogastric adenocarcinoma: propensity score-matched study.

BACKGROUND: Perioperative FLOT (fluorouracil plus leucovorin, oxaliplatin, and docetaxel) chemotherapy is a recent regimen used to treat resectable oesophagogastric (OG) adenocarcinoma, associated with improved overall survival versus earlier chemotherapy strategies. This study compared short-term perioperative morbidity in a large tertiary centre series of FLOT to a matched cohort receiving ECX/ECF (epirubicin, cisplatin, capecitabine (X) or 5-fluorouracil (F)). METHODS: Consecutive patients completing four perioperative cycles of FLOT and proceeding to surgery with resectable OG adenocarcinoma were included. This was matched to patients from a historic ECX/ECF cohort from the same institution. A propensity score was calculated, and a secondary analysis using a propensity-matched group performed. RESULTS: Cohorts were matched by tumour location and operations performed. In total there were 129 (64.5 per cent) oesophageal and 71 (35.5 per cent) gastric resections (FLOT 57 oesophageal, 43 gastric; ECF/ECX 64 oesophageal, 36 gastric). The median length of stay after surgery was 12 days in the FLOT group versus 15 in ECF/ECX (P = 0.035). There were no significant differences in overall perioperative complications and, specifically, no difference in OG anastomotic leaks, analysed by site (gastric (FLOT 0/79 (0 per cent) versus ECX 2/79 (2.5 per cent); P = 0.123), oesophageal (FLOT 4/121 (3.3 per cent) versus ECX 5/121 (4.1 per cent); P = 0.868) or type of surgery (open FLOT 1/121 (0.8 per cent) versus ECX 3/121 (2.5 per cent); P = 0.368; minimally invasive (FLOT 3/121 (2.5 per cent) versus ECX 2/121 (1.7 per cent); P = 0.555)). There was no statistical difference in leak-related return to theatre, 30-day (FLOT 0 (0 per cent) versus ECX 3/100 (3.0 per cent); P = 0.081), or 90-day (FLOT 0 (0 per cent) versus ECX 2/100 (2.0 per cent); P = 0.155) mortality. CONCLUSION: In terms of surgical complications, FLOT and ECX/ECF were equally safe in patients undergoing resection for OG adenocarcinoma.

Effect of peri-operative chemotherapy regimen on survival in the treatment of locally advanced oesophago-gastric adenocarcinoma - A comparison of the FLOT and 'MAGIC' regimens.

BACKGROUND: Peri-operative chemotherapy improves survival in patients with locally advanced oesophago-gastric adenocarcinoma. Two regimens with proven survival benefits are epirubicin, cisplatin plus capecitabine or fluorouracil (Medical Research Council Adjuvant Gastric Infusional Chemotherapy, MAGIC) and fluorouracil plus leucovorin, oxaliplatin, and docetaxel (FLOT). This study aimed to compare the effect of these regimens on survival (primary aim) and pathological response, surgical complications, adverse events and chemotherapy completion rates. METHODS: Cohort study including 946 patients treated with FLOT (n = 257) or MAGIC (n = 689) who underwent surgical resection for oesophageal (n = 743) or gastric (n = 203) adenocarcinoma between 2002 and 2021 at St Thomas' Hospital or The Royal Marsden Hospital, London, UK. Survival analysis was performed using multivariable Cox regression, providing hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for age, sex, clinical T-stage, clinical N-stage, tumour grade and presence of signet ring cells. RESULTS: Patients treated with FLOT had better overall survival (HR = 0.69, 95% CI 0.50-0.94) and disease-free survival (HR = 0.75, 95% CI 0.58-0.98) than MAGIC. Patients treated with FLOT were more likely to have a complete pathological response (9.5% FLOT versus 5.5% MAGIC, p = 0.027) and were less likely to have a positive resection margin (19.1% FLOT versus 32.2% MAGIC, p < 0.001). The stratified analysis revealed similar results for oesophageal and gastric tumours. Rates of surgical complications, chemotherapy-associated adverse events and completion were similarly distributed between treatment groups. CONCLUSIONS: Patients with oesophageal or gastric adenocarcinoma treated with peri-operative FLOT had better survival and pathological response than those treated with peri-operative MAGIC. Rates of surgical complications, adverse events and chemotherapy completion were comparable.

Virus-induced Volatile Organic Compounds Are Detectable in Exhaled Breath during Pulmonary Infection.

Rationale: Chronic obstructive pulmonary disease (COPD) is a condition punctuated by acute exacerbations commonly triggered by viral and/or bacterial infection. Early identification of exacerbation triggers is important to guide appropriate therapy, but currently available tests are slow and imprecise. Volatile organic compounds (VOCs) can be detected in exhaled breath and have the potential to be rapid tissue-specific biomarkers of infection etiology. Objectives: To determine whether volatile organic compound measurement could distinguish viral from bacterial infection in COPD. Methods: We used serial sampling within in vitro and in vivo studies to elucidate the dynamic changes that occur in VOC production during acute respiratory viral infection. Highly sensitive gas chromatography-mass spectrometry techniques were used to measure VOC production from infected airway epithelial-cell cultures and in exhaled breath samples from healthy subjects experimentally challenged with rhinovirus (RV)-A16 and from subjects with COPD with naturally occurring exacerbations. Measurements and Main Results: We identified a novel VOC signature comprising decane and other long-chain alkane compounds that is induced during RV infection of cultured airway epithelial cells and is also increased in the exhaled breath from healthy subjects experimentally challenged with RV and from patients with COPD during naturally occurring viral exacerbations. These compounds correlated with the magnitude of antiviral immune responses, viral burden, and exacerbation severity but were not induced by bacterial infection, suggesting that they represent a specific virus-inducible signature. Conclusions: Our study highlights the potential for measurement of exhaled breath VOCs as rapid, noninvasive biomarkers of viral infection. Further studies are needed to determine whether measurement of these signatures could be used to guide more targeted therapy with antibiotic/antiviral agents for COPD exacerbations.

Is Re-introducing Major Open and Minimally Invasive Surgery during COVID-19 Safe for Patients and Healthcare Workers? An International, Multi-centre Cohort Study in the Field of Oesophago-gastric Surgery.

INTRODUCTION: The COVID-19 pandemic has resulted in unparalleled changes to patient care, including the suspension of cancer surgery. Concerns regarding COVID-19-related risks to patients and healthcare workers with the re-introduction of major complex minimally invasive and open surgery have been raised. This study examines the COVID-19 related risks to patients and healthcare workers following the re-introduction of major oesophago-gastric (EG) surgery. PATIENTS AND METHODS: This was an international, multi-centre, observational study of consecutive patients treated by open and minimally invasive oesophagectomy and gastrectomy for malignant or benign disease. Patients were recruited from nine European centres serving regions with a high population incidence of COVID-19 between 1 May and 1 July 2020. The primary endpoint was 30-day COVID-19-related mortality. All staff involved in the operative care of patients were invited to complete a health-related survey to assess the incidence of COVID-19 in this group. RESULTS: In total, 158 patients were included in the study (71 oesophagectomy, 82 gastrectomy). Overall, 87 patients (57%) underwent MIS (59 oesophagectomy, 28 gastrectomy). A total of 403 staff were eligible for inclusion, of whom 313 (78%) completed the health survey. Approaches to mitigate against the risks of COVID-19 for patients and staff varied amongst centres. No patients developed COVID-19 in the post-operative period. Two healthcare workers developed self-limiting COVID-19. CONCLUSIONS: Precautions to minimise the risk of COVID-19 infection have enabled the safe re-introduction of minimally invasive and open EG surgery for both patients and staff. Further studies are necessary to determine the minimum requirements for mitigations against COVID-19.

The Mutational Concordance of Fixed Formalin Paraffin Embedded and Fresh Frozen Gastro-Oesophageal Tumours Using Whole Exome Sequencing.

1. BACKGROUND: The application of massively parallel sequencing has led to the identification of aberrant druggable pathways and somatic mutations within therapeutically relevant genes in gastro-oesophageal cancer. Given the widespread use of formalin-fixed paraffin-embedded (FFPE) samples in the study of this disease, it would be beneficial, especially for the purposes of biomarker evaluation, to assess the concordance between comprehensive exome-wide sequencing data from archival FFPE samples originating from a prospective clinical study and those derived from fresh-frozen material. 2. METHODS: We analysed whole-exome sequencing data to define the mutational concordance of 16 matched fresh-frozen and FFPE gastro-oesophageal tumours (N = 32) from a prospective clinical study. We assessed DNA integrity prior to sequencing and then identified coding mutations in genes that have previously been implicated in other cancers. In addition, we calculated the mutant-allele heterogeneity (MATH) for these samples. 3. RESULTS: Although there was increased degradation of DNA in FFPE samples compared with frozen samples, sequencing data from only two FFPE samples failed to reach an adequate mapping quality threshold. Using a filtering threshold of mutant read counts of at least ten and a minimum of 5% variant allele frequency (VAF) we found that there was a high median mutational concordance of 97% (range 80.1-98.68%) between fresh-frozen and FFPE gastro-oesophageal tumour-derived exomes. However, the majority of FFPE tumours had higher mutant-allele heterogeneity (MATH) scores when compared with corresponding frozen tumours (p < 0.001), suggesting that FFPE-based exome sequencing is likely to over-represent tumour heterogeneity in FFPE samples compared to fresh-frozen samples. Furthermore, we identified coding mutations in 120 cancer-related genes, including those associated with chromatin remodelling and Wnt/ß-catenin and Receptor Tyrosine Kinase signalling. 4. CONCLUSIONS: These data suggest that comprehensive genomic data can be generated from exome sequencing of selected DNA samples extracted from archival FFPE gastro-oesophageal tumour tissues within the context of prospective clinical trials.