Positive Circumferential Resection Margin Research Articles

The professional seniority affects the clinical application of total neoadjuvant therapy for locally advanced rectal cancer.

e15590 Background: Total neoadjuvant therapy (TNT) integrates whole planned systemic chemotherapy within standard neoadjuvant protocols either before or after radiotherapy for locally advanced rectal cancer (LARC). Preference of neoadjuvant treatment type may vary among the medical oncologists. This study aimed to evaluate impact of professional seniority on TNT approach for LARC. Methods: A 20-item questionnaire was presented to medical oncologists as a cross-sectional survey during a national oncology congress via tablets. The evaluation was stratified by position; early-career oncologists (ECOs) and seniors. 2 questions were about experience regarding rectal cancer treatment. 5 questions were about physicians’ choice of screening and treatment in LARC and the factors affecting their treatment choices. 13 questions were about TNT approach (the sequencing of treatment, denominators of sequencing, chemotherapy choice, treatment response evaluation, operation preferences, adjuvant treatment and its denominators). Results: 189 medical oncologists were included (62.4% (n = 118) ECOs). An endorectal ultrasound was significantly preferred by the seniors (p = 0.039) in addition to conventional staging tools. 65.6% (n = 124) of the participants preferred long-course chemoradiation as their favorite neoadjuvant treatment approach. External sphincter invasion, threatened circumferential resection margin (CRM) and clinical stage were the most common denominators of TNT regardless of experience. ECOs favored short-course RT (p = 0.009) while the seniors chose long-course chemoradiotherapy (p = 0.041) as the index step of TNT. 57% (n = 108) of the physicians preferred to monitor treatment response for TNT at 8-weeks periods. Almost half of the participants (47.1%) reported pathological complete response (pCR) rates between 25-50% with TNT in their clinical practice. The physicians who prefer to give adjuvant treatment after completion of TNT make individualized decisions when surgical pathology reveals non-pCR, CRM and lymph node involvement. There was a significant difference between the ECOs and seniors (63.6 vs 45.1%, p = 0.013) in terms of choosing the adjuvant chemotherapy based on CRM positivity. Majority of the senior medical oncologists (88%) and ECOs (76.3%) agree that TNT should be the standardized neoadjuvant treatment approach for LARC. The preferred adjuvant chemotherapy after TNT was capecitabine-oxaliplatin (51.1%) or capecitabine alone (46%). Conclusions: TNT for LARC is well accepted among the medical oncologists and the professional seniority seems to affect its clinical application.

Regional variance in treatment and outcomes of locally invasive (T4) rectal cancer in Australia and New Zealand: analysis of the Bi-National Colorectal Cancer Audit.

BackgroundsLocally invasive T4 rectal cancer often requires neoadjuvant treatment followed by multi‐visceral surgery to achieve a radical resection (R0), and referral to a specialized exenteration quaternary centre is typically recommended. The aim of this study was to explore regional variance in treatment and outcomes of patients with locally advanced rectal cancer in Australia and New Zealand (ANZ).MethodsData were collected from the Bi‐National Colorectal Cancer Audit (BCCA) database. Rectal cancer patients treated between 2007 and 2019 were divided into six groups based on region (state/country) using patient postcode. A subset analysis of patients with T4 cancer was performed. Primary outcomes were positive circumferential resection margin (CRM+), and positive circumferential and/or distal resection margin (CRM/DRM+).ResultsA total of 9385 patients with rectal cancer were identified, with an overall CRM+ rate of 6.4% and CRM/DRM+ rate of 8.6%. There were 1350 patients with T4 rectal cancer (14.4%). For these patients, CRM+ rate was 18.5%, and CRM/DRM+ rate was 24.1%. Significant regional variation in CRM+ (range 13.4–26.0%; p = 0.025) and CRM/DRM+ rates (range 16.1–29.3%; p = 0.005) was identified. In addition, regions with higher CRM+ and CRM/DRM+ rates reported lower rates of multi‐visceral resections: range 24.3–26.8%, versus 32.6–37.3% for regions with lower CRM+ and CRM/DRM+ rates (p < 0.0001).ConclusionPositive resection margins and rates of multi‐visceral resection vary between the different regions of ANZ. A small subset of patients with T4 rectal cancer are particularly at risk, further supporting the concept of referral to specialized exenteration centres for potentially curative multi‐visceral resection.

145: THE USE OF MACHINE LEARNING FOR REAL-TIME DETECTION OF OESOPHAGEAL AND GASTRIC CANCER BASED ON DIFFUSE REFLECTANCE SPECTROSCOPY: A VALIDATION STUDY

Abstract Background and aim The lack of a fast and accurate intraoperative tumour margin assessment tool contributes to high positive circumferential resection margin rates for oesophageal and gastric cancers, which is associated with local recurrence and poor long-term survival. Diffuse reflectance spectroscopy (DRS) can provide non-invasive, accurate, and real-time tissue classification based on quantification of light reflectance in tissue, providing a unique optical fingerprint of the tissue. This study aimed to validate the use of DRS for discrimination between normal and cancerous tissues based on ex-vivo gastric and oesophageal cancer resection specimens. Methods Consecutive patients undergoing resections for gastric and oesophageal carcinomas at a tertiary referral centre in London between July 2020 and June 2021 were included. Reflectance data in the 468-720 nm spectral range were recorded on ex-vivo specimens within 15 minutes of surgical specimen excision. Based on video recordings of the data acquisition procedure and probe tip tracking, sampling sites were correlated with histological reports manually labeled as either normal or cancer (Figure 1). Following spectral data normalisation and feature selection, four supervised machine learning approaches were tested for classification using 5-fold cross-validation. Overall classification accuracy and Area Under the Curve (AUC) across machine learning approaches were compared. Results A total of 32 patients (median age 68, 75% male) were included. 11,862 mean spectra (2990 spectra for normal oesophagus, 4628 for normal stomach, 2305 for gastric cancer, and 1939 for oesophageal cancer) were collected. For oesophageal cancer, classification accuracy was 96.22 ± 0.50 and AUC was 99.24 ± 0.19, while for gastric cancer, the accuracy was 93.86 ± 0.66, and AUC 98.50 ± 0.28 for gastric cancer. For both malignancy types, Extreme Gradient Boosting was the best performing classifier. The differences in spectral data between patients receiving neoadjuvant treatment and treatment naïve were non-significant. Conclusion Machine learning can be used to accurately differentiate between normal and cancerous oesophageal and gastric tissues in an ex-vivo setting, based on DRS data. Features used for class discrimination should be investigated to find possible physiological correlates of spectral data differences. Future intraoperative validation is required to assess the utility of this technology for real-time tumour margin mapping and its effect on long-term outcomes.

Feasibility of the semi-opened method of specimen resection for a circumferential resection margin in rectal cancer surgery: a multicenter study.

A circumferential resection margin (CRM) > 1mm is a surrogate marker of oncologic outcomes in rectal cancer patients. In Japan, because the mesentery is removed from the rectum, the CRM cannot be measured. This multicenter prospective study evaluates the feasibility of a resected specimen processing method that allows CRM measurement. Fifty patients with rectal cancer were enrolled. Resected specimens were processed as previously reported. The primary outcomes were CRM measurement and the rate of CRM positivity. The secondary outcomes were the quality of total mesorectal excision, the possibility to visualize and sample the tumor, the number of harvested lymph nodes, and comparison between the pathological CRM and preoperative mesorectal fascia (MRF) involvement. This study was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry under identification number UMIN000031735. The CRM was measurable in all patients and found to be positive in three (6%). We confirmed tumor localization, sampled the tumor, and measured the distal margin in all patients. A median of 20 lymph nodes were harvested. The concordance rate between preoperative MRF involvement and pathological CRM status was 90%. A semi-opened rectal specimen with transverse slicing is a feasible method for measuring the CRM.

Development and Validation of the Optimal Circumferential Resection Margin in Pathological T3 Esophageal Cancer: A Multicenter, Retrospective Study.

The clinical significance of circumferential resection margin (CRM) in esophageal squamous cell carcinoma (ESCC) remains unclear. Optimal CRM for predicting the recurrence of pathological T3 ESCC was investigated. Seventy-three patients were retrospectively investigated in the development cohort. Patients were divided into CRM-negative and CRM-positive groups, and clinicopathological factors and survival outcomes were compared between the groups. The cutoff value was validated in another validation cohort (n = 99). Receiver operating characteristic analysis in the development cohort showed the cutoff value of CRM was 600 μm. In the validation cohort, patients in the CRM-positive group showed a significantly higher rate of locoregional recurrence (p = 0.006) and worse recurrence-free survival (RFS) (p < 0.001) than those in the CRM-negative group. Multivariate analysis identified positive CRM as an independent predictive factor for poor RFS (hazard ratio, 2.695; 95% confidence interval, 1.492-4.867; p = 0.001). The predictive value of our criteria of positive CRM for RFS was higher than that of the Royal College of Pathologists (RCP) and the College of American Pathologists (CAP) criteria. Stratified analysis in the neoadjuvant chemotherapy groups also revealed that the rate of locoregional recurrence was higher in the CRM-positive group than in the CRM-negative group both in the pathological N0 and N1-3 subgroups. CRM of 600 μm can be the optimal cutoff value rather than the RCP and CAP criteria for predicting locoregional recurrence after esophagectomy. These results may support the impact of perioperative locoregional control of locally advanced ESCC.

Positive circumferential resection margin in locally advanced esophageal cancer: an updated systematic review and meta-analysis.

The impact of positive circumferential resection margin on prognosis in esophageal cancer is under controversy. Previous systematic reviews and meta-analyses had limitations. This updated systematic review and meta-analysis aimed to assess the prognostic impact of positive circumferential resection margin in esophageal cancer.PubMed and Web of Science were searched for studies investigating the association between circumferential resection margin status and prognosis in esophageal cancer. Study population were focused on T3 and/or T4a patients. Study selection was based on availability of survival information (Kaplan-Meier curves and adjusted analysis). Random-effects models were used to summarize hazard ratios for overall survival and disease-free survival.According to College of American Pathologists criteria, circumferential resection margin-positive patients had shorter median overall survival (P < 0.0001) and shorter median disease-free survival (P < 0.0001) compared with circumferential resection margin-negative patients. The pooled hazard ratios for overall survival and disease-free survival were 2.06 (95% confidence interval, 1.68-2.53; P < 0.0001) and 2.00 (95% confidence interval, 1.41-2.84; P < 0.0001), respectively. According to the Royal College of Pathologists criteria, circumferential resection margin-positive patients had shorter median overall survival (P < 0.0001) and shorter median disease-free survival (P < 0.0001) compared with circumferential resection margin-negative patients. The pooled hazard ratios for overall survival and disease-free survival were 1.31 (95% confidence interval, 1.16-1.48; P < 0.0001) and 1.31 (95% confidence interval, 1.09-1.57; P < 0.0001), respectively.ompared with negative circumferential resection margin, positive circumferential resection margin is associated with worse survival outcomes in esophageal cancer.

Side-to-side choledochoduodenostomy for common bile duct stones.

The management of lower rectal cancers is a therapeutic challenge both from the oncological and functional viewpoints. The aim of this study is to assess the oncological results and postoperative morbidity after transanal total mesorectal excision (TaTME) for low rectal cancer.In this monocentric retrospective study, we compared the quality of carcinologic resection and the morbidity-mortality between a group of 20 patients undergoing TaTME and 21 patients treated by abdomino-perineal resection (APR) between 2016 to 2019.More patients had a positive circumferential resection margin (CRM) (≤ 1 mm) in the APR group (47.6% vs. 5%; P < 0.0036). The difference in the rates of grades I-II and III-IV complications (Clavien-Dindo classification) between the two groups was not statistically significant (50% vs. 57.1% and 5% vs. 9.5% in TaTME and APR, respectively; P = 0.7579, P = 1.00). The median follow-up was longer in the TaTME group (20 months vs. 11 months; P = 0.58). The local recurrence rate did not differ between the two groups (5% vs. 4.8%; P = 1.00)TaTME provides a reliable total mesorectal resection with an acceptable CRM. However, like any new technique, it requires experience and the learning curve is long.

Robotic versus laparoscopic surgery for middle and low rectal cancer (REAL): Short-term outcomes of a multicenter randomized controlled trial.

14 Background: Robotic surgery for rectal cancer is gaining popularity, but persuasive evidence on long-term oncological outcomes is lacking. This multicenter randomized controlled trial compared robotic and conventional laparoscopic surgery regarding surgical quality and long-term oncological outcomes among patients with middle and low rectal cancer. Methods: This superiority trial was undertaken at 11 hospitals in 8 Chinese provinces. Patients with middle (&gt; 7–12 cm from anal verge) or low (0–7 cm from anal verge) rectal adenocarcinoma, cT1–T3 N0–1 or ycT1–T3 Nx after preoperative radio-/chemoradiotherapy, and no evidence of distant metastasis were enrolled and randomly assigned in a 1:1 ratio to receive robotic or conventional laparoscopic surgery. Secondary (short-term) end points (surgical quality, pathological radicality, and postoperative recovery) were compared using modified intention-to-treat (mITT) analysis. Three-year locoregional recurrence rate as the primary endpoint is expected by the end of 2023. This trial was registered with ClinicalTrials.gov (NCT02817126). Results: Between July 2016 and December 2020, 1240 patients were enrolled; 1180 were included in the mITT analysis (591 in robotic and 589 in laparoscopic group). There were significantly more sphincter-preserving surgeries (low anterior resections) performed in the robotic group (83.1% vs. 76.9%, p = 0.008). With more macroscopic complete resections (95.4% vs. 91.9%, p = 0.012), robotic surgery had better integrity of the mesorectal fascia, and had lower circumferential resection margin positivity rate (4.0% vs. 7.1%, difference = -3.1%, 95% confidence interval = -6.0% to -0.5%, p = 0.023) and more lymph nodes harvested (median, 15.0 vs. 14.0, p = 0.004). Robotic surgery also reduced the open conversion rate (1.7% vs. 3.9%, p = 0.021), estimated blood loss (median, 40.0 ml vs. 50.0 ml, p &lt; 0.001), intraoperative complication rate (5.4% vs. 8.7%, p = 0.029), and 30-day postoperative complication rate (Clavien-Dindo grade II or higher, 16.1% vs. 22.9%, p = 0.003), leading to better postoperative recovery and shorter postoperative hospital stay (median, 7.0 days vs. 8.0 days, p &lt; 0.001). The 30-day postoperative mortality was similar between the two groups (0.2% vs. 0.2%, p &gt; 0.999). Conclusions: Robotic surgery for middle and low rectal cancer significantly reduced surgical injury, improved oncological radicality, and promoted postoperative recovery compared with conventional laparoscopic surgery. Clinical trial information: NCT02817126.

Omission of neoadjuvant radiotherapy for clinical T2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins.

PurposeFor moderately advanced rectal cancers with safe circumferential margins, the oncologic benefit of neoadjuvant radiotherapy must be reconsidered because of the possibility of overtreatment, resulting in complications from radiotoxicity. To evaluate the oncologic safety of the omission of neoadjuvant radiotherapy for moderately advanced rectal cancers, we evaluated and compared the prognoses of patients who underwent radical resection with and without neoadjuvant radiotherapy for T2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins.MethodsWe retrospectively enrolled 66 patients who underwent radical resection for clinical (c) T2N1 and T3N0/1 middle and low rectal cancers between 2008 and 2014. Patients with distant metastasis; cT4, cN2, or positive lateral pelvic lymph nodes; positive circumferential resection margin; signet-ring cell carcinoma; cT1/2N0; or those who had received adjuvant radiotherapy were excluded. The clinical and pathological characteristics and 5-year oncologic outcomes of the no-radiotherapy (n = 34) and radiotherapy (n = 32) groups were compared.ResultsThe rates of abdominoperineal resection and ileostomies and the proportion of patients who received adjuvant chemotherapy were significantly higher in the radiotherapy group. There were no significant differences in tumor location, clinical stage, surgery type, pathologic N stage, anastomotic leakage, or long-term oncologic outcomes including 5-year disease-free survival, overall survival, and local recurrence and distant metastasis rates between both groups.ConclusionThe oncologic benefit of neoadjuvant radiotherapy for cT2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins is considered unclear, and it can be omitted to prevent radiotoxicity and facilitate prompt essential treatment.

Role of Donuts and Safe Resection Margins in Rectal Cancer Surgery

Resection margins in rectal cancer surgery have a pivotal role in assessing the adequacy of surgery as well as playing an important role in determining the prognosis for the patient. With better understanding of tumor biology, more importance is being laid on circumferential resection margin (CRM) rather than distal/proximal resection margin. Positive CRM is an important predictor for increased local recurrence rates. The length of safe distal resection margin in rectal cancer surgery has reduced significantly over the past few decades, with no significant change in the prognosis of patients. To avoid permanent stoma, more and more sphincter saving procedures are being performed, and this has been made possible as a result of more and more use of staplers. While using staplers, donuts are produced from the two resected ends and there is controversy whether these should be sent for histopathological examination or not. In this article, we discuss the importance of resection margins and donuts in rectal cancer surgery.

Variation in the volume-outcome relationship after rectal cancer surgery in the United States: Retrospective study with implications for regionalization

BackgroundPrevious studies have demonstrated improved outcomes for patients with rectal cancer treated at higher-volume hospitals. However, little is known whether heterogeneity in this effect exists. The objective was to test whether the effect of increased annual rectal cancer resection volume on outcomes is consistent across all hospitals treating rectal cancer. MethodsAdult stage I to III patients who underwent surgical resection for rectal adenocarcinoma from 2004 to 2016 were identified in the National Cancer Database. ResultsWe included 120,522 patients treated at 763 hospitals in this retrospective cohort study. Higher volume was linearly and incrementally related to outcomes in unadjusted analyses. In adjusted models, for an average patient at the average hospital, the effect of increasing the annual caseload of rectal cancer resections by 20 resections per year was associated with 8%, (hazard ratio = 0.92, 95% confidence interval = 0.87, 0.97), 18% (odds ratio = 0.82, 95% confidence interval = 0.70, 0.98), and 16% (odds ratio = 0.84, 95% confidence interval = 0.73, 0.95) relative reductions in 5-year overall survival, 30-, and 90-day mortality, respectively, and with a 19% (odds ratio = 1.19, 95% confidence interval = 1.04, 1.36) relative increase in the rate of neoadjuvant chemoradiation. These effects varied by individual hospitals such that 39% of hospitals do not see any benefit in 5-year overall survival associated with higher volumes. Increased volume was associated with lower positive circumferential resection margin rates at 19% of the hospitals. ConclusionThis study confirms that higher-volume hospitals have improved outcomes after rectal cancer surgery. However, there exists significant variation in these effects induced by individual within-hospital effects. Regionalization policies may need to be flexible in identifying the hospitals that would achieve enhanced benefits from treating a larger volume of patients.

Quality Indicators of Transanal Total Mesorectal Excision (TaTME) for Rectal Cancer

Abstract Introduction Transanal total mesorectal excision (TaTME) has revolutionized the surgical techniques for lower-third rectal cancer. The aim of the present study was to analyze the outcomes of quality indicators of TaTME for rectal cancer compared with laparoscopic TME (LaTME). Methods A cohort prospective study with 50 (14 female and 36 male) patients, with a mean age of 67 (range: 55.75 to 75.25) years, who underwent surgery for rectal cancer. In total, 20 patients underwent TaTME, and 30, LaTME. Every TaTME procedure was performed by experienced colorectal surgeons. The sample was divided into two groups (TaTME and LaTME), and the quality indicators of the surgery for rectal cancer were analyzed. Results There were no statistically significant differences regarding the patients and the main characteristics of the tumor (age, gender, American Society of Anesthesiologists [ASA] score, body mass index [BMI], tumoral stage, neoadjuvant therapy, and distance from the tumor to the external anal margin) between the two groups. The rates of: postoperative morbidity (TaTME: 35%; LaTME: 30%; p = 0.763); mortality (0%); anastomotic leak (TaTME: 10%; LaTME: 13%; p = 0.722); wound infection (TaTME: 0%; LaTME: 3.3%; p = 0.409); reoperation (TaTME: 5%; LaTME: 6.6%; p = 0.808); and readmission (TaTME: 5%; LaTME: 0%; p = 0.400), as well as the length of the hospital stay (TaTME: 13.5 days; LaTME: 11 days; p = 0.538), were similar in both groups. There were no statistically significant differences in the rates of positive circumferential resection margin (TaTME: 5%; LaTME: 3.3%; p = 0.989) and positive distal resection margin (TaTME: 0%; LaTME: 3.3%; p = 0.400), the completeness of the TME (TaTME: 100%; LaTME: 100%), and the number of lymph nodes harvested (TaTME: 15; LaTME: 15.5; p = 0.882) between two groups. Conclusion Transanal total mesorectal excision is a safe and feasible surgical procedure for middle/lower-third rectal cancer.

Local Recurrence and Disease-Free Survival After Transanal Total Mesorectal Excision: Results From the International TaTME Registry.

The oncologic safety of transanal total mesorectal excision (TaTME) for rectal cancer has recently been questioned, with high local recurrence (LR) rates reported in Dutch and Norwegian experiences. The objective of this study was to evaluate the oncologic safety of TaTME in a large cohort of patients with primary rectal cancer, primarily in terms of LR, disease-free survival (DFS), and overall survival (OS). This was a prospective international registry cohort study, including all patients who underwent TaTME for primary rectal adenocarcinoma from February 2010 through December 2018. The main endpoints were 2-year LR rate, pattern of LR, and independent risk factors for LR. Secondary endpoints included 2-year DFS and OS rates. Kaplan-Meier survival analysis was used to calculate actuarial LR, DFS, and OS rates. A total of 2,803 patients receiving primary TaTME were included, predominantly men (71%) with a median age of 65 years (interquartile ratio, 57-73 years). After a median follow-up of 24 months (interquartile ratio, 12-38 months), the 2-year LR rate was 4.8% (95% CI, 3.8%-5.8%) with a unifocal LR pattern in 99 of 103 patients (96%). Independent risk factors for LR were male sex, threatened resection margin on baseline MRI, pathologic stage III cancer, and a positive circumferential resection margin on final histopathology. The 2-year DFS and OS rates were 77% (95% CI, 75%-79%) and 92% (95% CI, 91%-93%), respectively. This largest TaTME cohort to date supports the oncologic safety of the TaTME technique for rectal cancer in patients treated in units that contributed to an international registry, with an acceptable 2-year LR rate and a predominantly unifocal LR pattern.

EP.TU.370A 5-year re-audit of quality indicators for potentially curative rectal cancer resections by a single surgeon

Abstract Aim High quality operations with low rates of tumour perforation and circumferential resection margin (CRM) positivity are associated with improved long-term outcomes following surgery for rectal cancer. Previous audit has demonstrated lower rates of tumour perforation and CRM positivity by a single surgeon compared to the published standards. Our aim is to re-audit this surgeons’ outcomes for curative rectal resections. Methods Data was collected retrospectively for all potentially curative rectal resections over a 5-year period performed by a single surgeon using a local database and electronic care records. The CRM status and tumour perforation status were considered. Other end points included the rate of local recurrence, survival and length of stay. Results Fifty-one patients underwent rectal resections with curative intent, with a median age of 67. Complete resection (R0) was achieved in 94.1% of cases; 3.92% were found to have nodes less than 1mm from the margin and 1.96% were found to have tumour deposit less than 1mm from the margin – these cases were considered to be an R1 resection. Tumour perforation was present in 3.92% of cases, all of which had occurred pre-operatively. Local recurrence was found in 5.88% of cases and 90-day mortality was 1.96%. Median length of hospital stay was 7 days. Conclusion Our data demonstrates sustained high quality surgical outcomes with low tumour perforation rates and CRM positivity rates which compare favourably with the published standards to date. Local recurrence rates are comparable to published standards and 90-day mortality continues to be low.

EP.TU.947Rectosigmoid Cancer Resection in a District General Hospital – A single centre experience

Abstract Aims To identify common factors amongst patients who had undergone rectosigmoid cancer resections Materials &amp; Methods This is a single centre retrospective study including patients who underwent recto-sigmoid cancer resections by a senior colo-rectal surgeon from year 2012 to 2018. Patients’ data were identified through a local trust database. Patients’ variables were subjected to Mann Whitney, Chi Square analysis and survival function plots. Results Of the 102 patients, we observed a mean age of 66 years with a slight male sex predisposition(58%) . Two-thirds were referred through the 2 week-wait GP pathway with predominant symptoms being bleeding and change in bowel habits (70 and 60% respectively). Male sex was associated with longer length of stay (LoS), younger age at surgery, higher T-staging and tumour size. Patients who had laparoscopic surgery converted to open and those with stoma had the longest LoS. Histological results of higher Dukes, T and N stage were associated with higher patient mortality rates. Advanced N and Dukes staging were also related to higher propensity of disease recurrence with new metastases. In those with positive circumferential resection margin (CRM) on histology, there were higher correlation with local and distal disease recurrences as well as higher post-op mortality rate (all the above had p-values &amp;lt;0.05). Conclusion The factors identified in previous large scale studies do correlate with our experience in a district general hospital and identification of sub-groups of patients at higher risk of adverse outcomes can be identified in further studies.

EP.TU.1069Improved Perioperative and Survival Outcomes for Minimally Invasive Rectal Surgery

Abstract Aim Although laparoscopic colon cancer surgery has been widely embraced as current evidence demonstrates comparable oncological results with open surgery, similar evidence is lacking for laparoscopic rectal cancer surgery. We present the outcomes of patients undergoing laparoscopic and open total mesorectal excision (TME) for rectal cancer in our unit. Methods We retrospectively analysed data collected for patients who underwent laparoscopic and open TME from January 2014 to December 2018. Sociodemographic, perioperative, circumferential resection margin (CRM) positivity, locoregional recurrence and survival data were analysed. Results 260 (144 laparoscopic and 116 open) were included. Median age in the laparoscopic group was 69 years and in the open group 68 years. Neoadjuvant therapy was given in 21 patients (14.6%) in laparoscopic and 13 (11.2%) in the open group (p = 0.42). CRM was positive in 16 cases (11.1%) laparoscopic and 32 (27.6%) open (p = 0.0007;95%CI:6.9-26.2). No statistically significant difference in anastomotic leak rate was observed both groups (4.9% laparoscopic vs 4.3% open;p=0.82). Surgical site infection was significantly more in open cases (13% vs 5.6% laparoscopic,p=0.04). Similar locoregional recurrence rates were observed in both groups (18% laparoscopic vs 19% open,p=0.84). Median follow up was 34 months or more allowed for Disease-free (DFS) and overall survival (OS) to be analysed for 144 of 260 patients. DFS and OS were better in laparoscopic (73% and 94%) compared to open (68% and 85% respectively) (p = 0.40 and p = 0.015 respectively). Conclusion From an oncological perspective, laparoscopic surgery for rectal cancer is safe with additional perioperative and survival benefits compared to open surgery.

1441 Real-World Comparison of Curative Open, Laparoscopic and Robotic Resections for Sigmoid and Rectal Cancer - Single Center Experience

Abstract Aim There is an increase in the utilization of robotic surgery in addition to traditional open or laparoscopic approaches. The aim of this study is to compare the short-term outcomes for open, laparoscopic, and robotic surgery for rectal and sigmoid cancer. Method One hundred and forty-seven patients (open n = 48, laparoscopic n = 49, robotic n = 50) undergoing curative resections by two surgeons, using a standardized technique, between 2013 and 2020 were included. Data analyzed included patient demographics, tumor characteristics, length of stay, post-operative outcomes, and pathologic surrogates of oncologic results, including total mesorectal excision (TME) quality, circumferential resection margin (CRM) involvement and lymph node (LN) yield. Results Median age of population was 68 years (IQR 59-73), majority (68%) were males. Median distance from anal verge in robotic surgery group was 8 cm, compared to 15 and 14.5 cm in the open and laparoscopic groups respectively, p = 0.029, (laparoscopic vs robotic, p = 0.005 and open vs robotic, p = 0.027). Proportion of patients who received neoadjuvant radiotherapy in robotic surgery group was higher, p = 0.04. In sub-group of tumors between 3 and 7 cm from anal verge more patients in the robotic surgery group had sphincter preservation, p = 0.006. Length of stay, maximum C-reactive protein, and white blood cell rise favored minimally invasive approaches compared to open surgery. There were no differences in post-operative complications, lymph node yield or CRM positivity rate between the three groups. Conclusions Robotic surgery approach is safe and allows sphincter preservation without compromising TME quality in rectal cancer surgery.

Short-Term Outcomes with Standardized Transperineal Minimally Invasive Abdominoperineal Excision for Rectal Cancer

BackgroundTransperineal abdominoperineal excision (TpAPE) is an emerging approach for low rectal cancers but is technically challenging. Based on an anatomical study we conducted previously, we have standardized the TpAPE procedure. Here, we aimed to validate the feasibility of the standardized TpAPE by investigating the short-term outcomes. MethodsFrom January 2018 to November 2020, a total of 405 patients underwent laparoscopic or robotic rectal resection for rectal cancer in our institution. For the current study, we analyzed data for the 31 patients who underwent TpAPE. The abdominal phase was performed synchronously with the perineal phase using either a laparoscopic or robotic approach. Short-term outcomes included operative and pathological results. ResultsOf the 31 cases, we identified anterior quadrant tumor invasion in 21. Most of the cases were advanced, with 6 staged as cT3 and 20 as T4. Of the 27 cases not involving distant metastasis, neoadjuvant therapy was performed in 19. No inadvertent rectal perforation or urethral injury was found intraoperatively. The median procedural duration to specimen removal was 250 min (interquartile range, 204–287), and the median intraoperative blood loss was 10 ml (interquartile range, 5–40). Regarding postoperative complications, perineal wound infection developed in 11 cases. A positive circumferential resection margin was found in 3, corresponding to the positive rate of 9.7%. These three cases were among the first 12 cases involving standardized TpAPE. ConclusionsThe current results indicate that TpAPE can be performed safely and might represent a useful option for low rectal cancer resection.

450 FACTORS AFFECTING CIRCUMFERENTIAL RESECTION MARGIN AFTER ESOPHAGECTOMY AND ITS PROGNOSTIC SIGNIFICANCE-LARGE SINGLE CENTRE EXPERIENCE

Abstract The evidence regarding the importance of circumferential resection margin (CRM) as a prognostic factor after esophagectomy is inconclusive in the era of neoadjuvant therapy. We retrospectively analysed our prospectively maintained database for factors that affect CRM positivity, and whether a positive CRM affects event free and overall survival. 2843 patients underwent esophagectomy with curative intent from October 2004 to 2019 at our centre. CRM was analysed as negative, close but technically free (&amp;lt;1 mm) and involved. Methods Data on the following variables was retrospectively extracted from prospective database. CRM status was noted for clinic-radiological T and N stage, level of growth, histology, differentiation grade and neoadjuvant treatment. Intra-operative details such as surgical procedure, approach, surgeon grade, lymphadenectomy and resection status were analysed. On final histopathology; proximal and distal margins, lymph node positivity, lymphovascular invasion(LVI), tumour regression grade(TRG) were analysed. The effect of CRM on development of recurrence and overall survival was evaluated. CRM data was available for 2439 (85.78%) patients. 71.2% of the patients received neoadjuvant chemotherapy. Factors were analysed separately for both close and positive margins. Results 75.8% had negative, 15.6% close and 8.6% positive CRM. Univariately, T stage, adenocarcinoma, poor differentiation, transhiatal approach, R+ resection, positive margins, TRG &amp;gt; 3, LVI and upfront surgery predicted positive CRM. On multivariate, negative CRM was seen in T1/T2 stage [OR 0.325, 95% CI-0.144-0.732, p = 0.007], squamous carcinoma [OR 0.574, 95% CI-0.351-0.958, p = 0.027], R0 resection [OR 0.228, 95% CI-0.086-0.599, p = 0.003] while positive CRM was seen in upfront surgery [OR 2.32, 95% CI-1.55-3.46, p &amp;lt; 0.001], positive nodes [OR 1.748, 95% CI-1.19-2.56, p = 0.004] and LVI [OR 2.73, 95% CI-1.87-3.98, p &amp;lt; 0.001]. Median event-free survival in CRM negative was 64 months compared to 14 months in CRM positive (p &amp;lt; 0.001). Conclusion Positive CRM involvement is a prognostic indicator in patients undergoing esophagectomy and associated with worse event-free and overall survival. CRM-positive disease in esophageal cancer may represent residual tumor, advanced disease, aggressive biology, or poor response to neoadjuvant treatment. All attempts should be made to achieve a clear circumferential resection margin. More evidence is needed to evaluate if adjuvant therapy is justified in these patients and the type of therapy also needs to be determined.

Is There an Optimal Definition for a Positive Circumferential Resection Margin in Locally Advanced Esophageal Cancer?

Two definitions of a positive circumferential resection margin (CRM) in esophageal cancer coexist: one by the College of American Pathologists (CAP) (CRM = 0 mm) and another by the Royal College of Pathologists (RCP) (CRM ≤ 1 mm). This study aimed to evaluate the prognostic value of both definitions in esophageal cancer and to identify a new cutoff value for the CRM to predict survival. Patients who underwent curative esophageal resection for locally advanced (≥ pT3) adenocarcinoma or squamous cell carcinoma were selected from 2007 to 2016. The CRM was reassessed using an ocular micrometer. Overall survival (OS) and disease-free survival were estimated with uni- and multivariate analyses. The study enrolled 283 patients: 48 with a positive CRM according to the CAP definition and 171 with a positive CRM according to the RCP definition. In the multivariate analysis, a positive CRM according to both definitions was significantly associated with a poor OS (CAP: hazard ratio [HR], 2.26, p < 0.001; RCP: HR, 1.42, p = 0.035). A CRM of 0 mm was predictive of a worse OS and DFS than a CRM of 1 mm or less (p < 0.0001), whereas no significant difference was found between a CRM greater than 1 mm and a CRM of 1 mm or less, indicating that the CAP definition was more accurate for predicting prognosis and recurrence. New cutoff CRM values of 100 µm in squamous cell carcinoma and 200 µm in adenocarcinoma were optimal for predicting OS. The CAP definition was more accurate for predicting prognosis and recurrence. The study identified a new cutoff value of CRM according to histologic type.