Robotic approach to colonic resection: For some or for all patients?

The robotic approach is rapidly gaining momentum in colorectal surgery. Its benefits in pelvic surgery have been extensively discussed and are well established amongst those who perform minimally invasive surgery. However, the same cannot be said for the robotic approach for colonic resection, where its role is still debated. Here we aim to provide an extensive debate between selective and absolute use of the robotic approach for colonic resection by combining the thoughts of experts in the field of robotic and minimally invasive colorectal surgery, dissecting all key aspects for a critical view on this exciting new paradigm in colorectal surgery.

Robotic transanal minimally invasive surgery (r-TAMIS): perioperative and short-term outcomes for local excision of rectal cancers.

BACKGROUND: Transanal minimally invasive surgery (TAMIS) is an advanced technique for excision of early rectal cancers. Robotic TAMIS (r-TAMIS) has been introduced as technical improvement and potential alternative to total mesorectal excision (TME) in early rectal cancers and in frail patients. This study reports the perioperative and short-term oncological outcomes of r-TAMIS for local excision of early-stage rectal cancers. METHODS: Retrospective analysis of a prospectively collected r-TAMIS database (July 2021-July 2023). Demographics, clinicopathological features, short-term outcomes, recurrences, and survival were investigated. RESULTS: Twenty patients were included. Median age and body mass index were 69.5 (62.0-77.7) years and 31.0 (21.0-36.5) kg/m2. Male sex was prevalent (n = 12, 60.0%). ASA III accounted for 66.7%. Median distance from anal verge was 7.5 (5.0-11.7) cm. Median operation time was 90.0 (60.0-112.5) minutes. Blood loss was minimal. There were no conversions. Median postoperative stay was 2.0 (1.0-3.0) days. Minor and major complication rates were 25.0% and 0%, respectively. Seventeen (85.0%) patients had an adenocarcinoma whilst three patients had an adenoma. R0 rate was 90.0%. Most tumours were pT1 (55.0%), followed by pT2 (25.0%). One patient (5.0%) had a pT3 tumour. Specimen and tumour maximal median diameter were 51.0 (41.0-62.0) mm and 21.5 (17.2-42.0) mm, respectively. Median specimen area was 193.1 (134.3-323.3) cm2. Median follow-up was 15.5 (10.0-24.0) months. One patient developed local recurrence (5.0%). CONCLUSIONS: r-TAMIS, with strict postoperative surveillance, is a safe and feasible approach for local excision of early rectal cancer and may have a role in surgically unfit and elderly patients who refuse or cannot undergo TME surgery. Future prospective multicentre large-scale studies are needed to report the long-term oncological outcomes.

Laparoscopic D3 oncological resection in splenic flexure cancer: Technical details and its impact on long-term survival.

AIM: The applicability of laparoscopic D3 oncological resection for splenic flexure cancer (SFC) surgery has not been fully explored due to technical difficulties and variations in surgical procedure. The aim of this work is to describe the feasibility of performing laparoscopic D3 resection in SFC and its impact on long-term survival. METHOD: A retrospective study on 47 out of 52 consecutive patients who underwent elective laparoscopic colectomy for SFC from December 2006 until December 2019 at Korea University Anam Hospital was performed. Data on patients' demographic and clinical features, surgical procedures, intraoperative and postoperative complications, pathological features and follow-up were collected. Categorical data are expressed as frequencies (n) and percentages (%). Continuous data are expressed as mean ± standard deviation and median (range). The Kaplan-Meier test was used to determine the overall survival (OS), progression-free survival (PFS) and disease-free survival (DFS). RESULTS: The median age of patients was 67.0 years (range 27-87 years) and 72.3% were men. Ten (21.3%) patients presented with an obstructing tumour and underwent an elective laparoscopic colectomy, while 68.1% of patients presented with Stage II and III disease. The conversion rate was 4.3% and the morbidity rate was 31.9%. There was one postoperative death secondary to splenic infarction and anastomotic leak leading to multi-organ failure. Four deaths occurred due to disease progression during a median follow-up of 63.8 months. The rate of recurrence was 20%, the 5-year OS was 89.6% and the 5-year PFS was 72.9%. After R0 resection, the 5-year OS was 91.5% and the 5-year DFS was 74.5%. CONCLUSION: Laparoscopic D3 colectomy for SFC is feasible, with an acceptable morbidity and long-term oncological outcome when performed by highly skilled laparoscopic colorectal surgeons with knowledge of the complex anatomy around the splenic flexure. Further randomized trials should be performed to determine the advantage of laparoscopic D3 colectomy over conventional colectomy for SFC.

International standardization and optimization group for intersphincteric resection (ISOG-ISR): modified Delphi consensus on anatomy, definition, indication, surgical technique, specimen description and functional outcome.

AIM: Intersphincteric resection (ISR) is an oncologically complex operation for very low-lying rectal cancers. Yet, definition, anatomical description, operative indications and operative approaches to ISR are not standardized. The aim of this study was to standardize the definition of ISR by reaching international consensus from the experts in the field. This standardization will allow meaningful comparison in the literature in the future. METHOD: A modified Delphi approach with three rounds of questionnaire was adopted. A total of 29 international experts from 11 countries were recruited for this study. Six domains with a total of 37 statements were examined, including anatomical definition; definition of intersphincteric dissection, intersphincteric resection (ISR) and ultra-low anterior resection (uLAR); indication for ISR; surgical technique of ISR; specimen description of ISR; and functional outcome assessment protocol. RESULTS: Three rounds of questionnaire were performed (response rate 100%, 89.6%, 89.6%). Agreement (≥80%) reached standardization on 36 statements. CONCLUSION: This study provides an international expert consensus-based definition and standardization of ISR. This is the first study standardizing terminology and definition of deep pelvis/anal canal anatomy from a surgical point of view. Intersphincteric dissection, ISR and uLAR were specifically defined for precise surgical description. Indication for ISR was determined by the rectal tumour's maximal radial infiltration (T stage) below the levator ani. A new surgical definition of T3isp was reached by consensus to define T3 low rectal tumours infiltrating the intersphincteric plane. A practical flowchart for surgical indication for uLAR/ISR/abdominoperineal resection was developed. A standardized ISR surgical technique and functional outcome assessment protocol was defined.

Utility of near infrared fluorescent cholangiography in detecting biliary structures during challenging minimally invasive cholecystectomy.

BACKGROUND: Surgeons can minimize the risk of bile duct injury (BDI) during challenging mini-invasive cholecystectomy through technical standardization by means of a precise anatomical landmark identification (Critical View of Safety) and advanced technology for biliary visualization. Among these systems, the adoption of magnified stereoscopic 3-dimensional view provided by robotic platforms and near infrared fluorescent cholangiography (NIRF-C) is the most promising. METHODS: In this prospective cohort study, we evaluated all consecutive minimally invasive cholecystectomies (laparoscopic and robotic) performed with NIRF-C between May 2022 and January 2023 at General Surgery Unit, Department of Health Sciences, University of Milan, San Paolo Hospital (Milan, Italy). Inclusions criteria were as follows: (1) acute cholecystitis (emergency group), (2) history of chronic cholecystitis or complicated cholelithiasis (deferred urgent group), (3) difficult cases (patients affected by cirrhosis, with scleroatrophic gallbladder or BMI > 35 kg/m2). For each group, the detection rate and visualization order of the main biliary structures were reported (cystic duct, CD; common hepatic duct, CHD; common bile duct, CBD; and CD-CHD junction). RESULTS: A total of 101 consecutive patients were enrolled, including 83 laparoscopic and 18 robotic cholecystectomies. All patients were stratified into three subgroups: (a) emergency group (n = 33, 32.7%), (b) deferred urgent group (n = 46, 45.5%), (c) difficult group (n = 22, 21.8%). Visualization of at least one biliary structure was possible in 94.1% of cases (95/101). Interestingly, all four main structures were detected in 43.6% of cases (44/101). The CD was the structure identified most frequently, being recognized in 91/101 patients (90.1%), followed by CBD (83.2%), CHD (62.4%), and CD-CHD junction (52.5%). In the subset of patients that underwent emergency surgery for AC, the CD-CHD confluence was identified in only 45.5% of cases. However, early and precise identification of CBD (75.8%) and CD (87.9%) allowed safe isolation, clipping, and transection of the cystic duct. In the deferred urgent group, the CBD and the CD were easily identified as first structure in a high percentage of cases (65.2% and 41.3% respectively), whereas the CD-CHD junction was the third structure to be identified in 67.4% of cases, the highest value among the three subgroups. In the difficult group, NIRF-C did not prove to be a useful tool for biliary visualization. The rates of failure of visualization were elevated: CBD (27.3%), CD (18.2%), CHD (54.5%), and CD-CHD (68.2%). CONCLUSIONS: NIRF-C is a powerful real-time diagnostic tool to detect CBD and CD during minimally invasive cholecystectomy, especially when inflammation due to acute or chronic cholecystitis subverted the anatomy of the hepatoduodenal ligament.

Robotic approach may be associated with a lower risk of lung metastases compared to laparoscopic approach for mid-low rectal cancer after neoadjuvant chemoradiotherapy: a multivariate analysis on long-term recurrence patterns.

PURPOSE: Describe differences on recurrence patterns of mid-low rectal cancers treated with neoadjuvant chemoradiotherapy and low anterior resection between laparoscopic and robotic approach. METHODS: Patients were identified from a prospectively maintained institutional database between 2006 and 2019. Demographics, clinicopathological features, recurrence, and survival were investigated. Cox regression analysis was performed for risk factor analysis. RESULTS: A total of 160 patients (36 laparoscopic and 124 robotic) were included. Systemic recurrence rate was higher in laparoscopic group (27.8 vs 12.1%, p = 0.023). Liver recurrence was similar (11.1 vs 4.0%). Lung recurrence was higher after laparoscopy (19.4 vs 6.5%, p = 0.019). Time to lung recurrence was shorter after laparoscopy (13.0 months, IQR 4.0-20.0) compared to robotic (23.5 months, IQR 17.0-42.7) with no statistical significance. Time to liver recurrence was similar between laparoscopy (19.5 months, IQR 4.7-37.5) and robotic (19.0 months, IQR 10.5-33.0). Median overall survival after lung recurrence was different (p = 0.021) between laparoscopy (19.0 months, IQR 16.0-67.0) and robotic (74.0 months, IQR 50.2-112.2). OS after liver recurrence was similar between groups. Overall survival and lung disease-free survival were different between the two groups (p = 0.032 and p = 0.020), while liver disease-free survival and local recurrence-free survival were not. Laparoscopy (p = 0.030; HR 3.074, 95% CI: 1.112-8.496) was a risk factor for lung disease-free survival on multivariate analysis. CONCLUSION: Lung recurrences were less frequent and with better overall survival in the robotic group. Liver recurrences were not influenced by choice of approach. Trials are needed to investigate why the robotic approach affects distant metastasis control.

Hereditary colorectal cancer syndromes and the COVID-19 pandemic: results from a survey conducted in patients enrolled in a dedicated registry.

PURPOSE: The coronavirus 2019 (COVID-19) pandemic has had profound consequences also for non-infected patients. This study aimed to evaluate the impact of the pandemic on the quality of life of a population with hereditary gastrointestinal cancer predisposition syndromes and on the surveillance/oncological care program of patients enrolled in a dedicated registry. METHODS: The study was conducted by means of an online self-report survey during the first Italian national lockdown. The survey comprised four sections: demographics; perception/knowledge of COVID-19; impact of the COVID-19 pandemic on surveillance and cancer care; health status (SF-12 questionnaire). RESULTS: 211 complete questionnaires were considered. 25.12% of respondents reported being not at all frightened by COVID-19, 63.98% felt "not at all" or "a little" more fragile than the healthy general population, and 66.82% felt the coronavirus to be no more dangerous to them than the healthy general population. 88.15% of respondents felt protected knowing they were monitored by a team of dedicated professionals. CONCLUSION: Patients with hereditary gastrointestinal cancer predisposition syndromes reported experiencing less fear related to COVID-19 than the healthy general population. The study results suggest that being enrolled in a dedicated registry can reassure patients, especially during health crises.

Chemoradiation and consolidation chemotherapy for rectal cancer provides a high rate of organ preservation with a very good long-term oncological outcome: a single-center cohort series.

AIM: To report long-term oncological outcomes and organ preservation rate with a chemoradiotherapy-consolidation chemotherapy (CRT-CNCT) treatment for locally advanced rectal cancer (LARC). METHOD: Retrospective analysis of prospectively maintained database was performed. Oncological outcomes of mid-low LARC patients (n=60) were analyzed after a follow-up of 63 (50-83) months. Patients with clinical complete response (cCR) were treated with the watch-and-wait (WW) protocol. Patients who could not achieve cCR were treated with total mesorectal excision (TME) or local excision (LE). RESULTS: Thirty-nine (65%) patients who achieved cCR were treated with the WW protocol. TME was performed in 15 (25%) patients and LE was performed in 6 (10%) patients. During the follow-up period, 10 (25.6%) patients in the WW group had regrowth (RG) and 3 (7.7%) had distant metastasis (DM). Five-year overall survival (OS) and disease-free survival (DFS) were 90.1% and 71.6%, respectively, in the WW group. Five-year OS and DFS were 94.9% (95% CI: 88-100%) and 80% (95% CI: 55.2-100%), respectively, in the RG group. For all patients (n=60), 5-year TME-free DFS was 57.3% (95% CI: 44.3-70.2%) and organ preservation-adapted DFS was 77.5% (95% CI: 66.4-88.4%). For the WW group (n=39), 5-year TME-free DFS was 77.5% (95% CI: 63.2-91.8%) and organ preservation-adapted DFS was 85.0% (95% CI: 72.3-97.8%). CONCLUSION: CRT-CNCT provides cCR as high as 2/3 of LARC patients. Regrowths, developed during follow-up, can be successfully salvaged without causing oncological disadvantage if strict surveillance is performed.

Risk factors for metachronous colorectal cancer in Lynch syndrome patients: a registry-based observational mono-institutional study cohort.

BACKGROUND: Risk factors for metachronous colorectal cancer (mCRC) in Lynch Syndrome (LS) patients are essential for colorectal cancer (CRC) treatment strategy to perform not only a curative but also preventive surgery. The aim of this study was to evaluate the risk factors for mCRC development in LS patients to define the patient subset that may benefit an extended curative and preventive surgical resection. METHODS: Patient's clinical history, oncological, molecular and follow-up were collected retrospectively from the Hereditary Digestive Tumors Registry at the National Cancer Institute of Milan. The age-related cumulative risk of mCRC was calculated using the Kaplan-Meier method. Factors significantly associated with mCRC were analyzed with a Cox regression model. Overall and specific competitive risks were also calculated. RESULTS: In a total of 1346 CRC patients, 159 (11.8%) developed a mCRC after a mean follow-up of 138 months from the primary tumor. The independent risk factors reported by a multivariate analysis were: pathogenetic variants in MLH1 and MSH2 (HR 2.96 and 1.91, respectively) and history of colorectal adenomas (HR 1.54); whereas female sex and extended surgery were protective (HR 0.59 and 0.79, respectively). CONCLUSIONS: Among a high-risk population for CRC, in particular LS, an extended surgery may be considered in CRC patients with specific risk factors (MLH1 or MSH2 germline pathogenic variants, history of colorectal adenomas) to reduce the risk of mCRC development.

Robotic Approach to Paediatric Gastrointestinal Diseases: A Systematic Review.

INTRODUCTION: The use of minimally invasive surgery (MIS) for paediatric surgery has been on the rise since the early 2000s and is complicated by factors unique to paediatric surgery. The rise of robotic surgery has presented an opportunity in MIS for children, and recent developments in the reductions in port sizes and single-port surgery offer promising prospects. This study aimed to present a systematic overview and analysis of the existing literature around the use of robotic platforms in the treatment of paediatric gastrointestinal diseases. MATERIALS AND METHODS: In accordance with the PRISMA Statement, a systematic review on paediatric robotic gastrointestinal surgery was conducted on Pubmed, Cochrane, and Scopus. A critical appraisal of the study was performed using the Newcastle Ottawa Scale. RESULTS: Fifteen studies were included, of which seven were on Hirschsprung's disease and eight on other indications. Included studies were heterogeneous in their populations, age, and sex, but all reported low incidences of intraoperative complications and conversions in their robotic cohorts. Only one study reported on a comparator cohort, with a longer operative time in the robotic cohort (180 vs. 152 and 156 min, p < 0.001), but no significant differences in blood loss, length of stay, intraoperative complications, postoperative complications, or conversion. CONCLUSIONS: Robotic surgery may play a role in the treatment of paediatric gastrointestinal diseases. There is limited data available on modern robotic platforms and almost no comparative data between any robotic platforms and conventional minimally invasive approaches. Further technological developments and research are needed to enhance our understanding of the potential that robotics may hold for the field of paediatric surgery.

Laparoscopic versus Open Emergency Surgery for Right Colon Cancers.

BACKGROUND: A laparoscopic approach to right colectomies for emergency right colon cancers is under investigation. This study compares perioperative and oncological long-term outcomes of right colon cancers undergoing laparoscopic or open emergency resections and identifies risk factors for survival. METHODS: Patients were identified from a prospectively maintained institutional database between 2009 and 2019. Demographics, clinicopathological features, recurrence, and survival were investigated. Cox regression analysis was performed for risk factor analysis. RESULTS: A total of 202 right colectomies (114 open and 88 laparoscopic) were included. ASA III-IV was higher in the open group. The conversion rate was 14.8%. Laparoscopic surgery was significantly longer (156 vs. 203 min, p < 0.001); pTNM staging did not differ. Laparoscopy was associated with higher lymph node yield, and showed better resection clearance (R0, 78.9 vs. 87.5%, p = 0.049) and shorter postoperative stay (12.5 vs. 8.0 days, p < 0.001). Complication rates and grade were similar. The median length of follow-up was significantly higher in the laparoscopic group (20.5 vs. 33.5 months, p < 0.001). Recurrences were similar (34.2 vs. 36.4%). Open surgery had lower five-year overall survival (OS, 27.1 vs. 51.7%, p = 0.001). Five-year disease-free survival was similar (DFS, 55.8 vs. 56.5%). Surgical approach, pN, pM, retrieved LNs, R stage, and complication severity were risk factors for OS upon multivariate analysis. Pathological N stage and R stage were risk factors for DFS upon multivariate analysis. CONCLUSIONS: A laparoscopic approach to right colon cancers in an emergency setting is safe in terms of perioperative and long-term oncological outcomes. Randomized control trials are required to further investigate these results.

Stereotactic Navigation-Assisted Laparoscopic Resection of Challenging Low Pelvic Tumors: A Case Series.

(1) Introduction: The laparoscopic approach to low pelvic tumors is challenging and hindered by suboptimal tumor visualization and dissection, with possible oncological failure. Stereotactic navigation provides real-time image guidance that may optimize safety, accuracy, and precision when dissecting challenging low pelvic tumors. (2) Methods: Preoperative CT images were acquired with eight skin-fixed fiducials and loaded into a navigation system. A patient tracker was mounted on the bed side. Patient-to-image paired point registration was performed, and an instrument tracker was mounted on a laparoscopic instrument and calibrated for instrument tracking. Surgical operations were performed with real-time stereotactic navigation assistance. (3) Results: Three patients underwent stereotactic navigation surgery. Fiducial registration errors were good to optimal (±1.9, ±3.4, and ±3.4 mm). Lesions were easily identified and targeted with real-time navigation. Surgeries were uneventful. Histopathology examinations identified one retro-rectal schwannoma, one lateral pelvic recurrence from rectal adenocarcinoma, and one advanced anal canal carcinoma. No navigation-related complications, readmissions, or postoperative mortalities were observed. (4) Conclusions: The application of laparoscopic stereotactic navigation surgery to complex low pelvic tumors is feasible and could impact oncological surgical quality by enabling tumor targeting and ensuring resection margins. Further wider series are needed to confirm stereotactic navigation's impact on challenging low pelvic tumors.

Robotic beyond total mesorectal excision (TME) for locally advanced or recurrent rectal cancer: a systematic review protocol.

INTRODUCTION: The surgical treatment for locally advanced or recurrent rectal cancer requires oncological clearance with a pelvic exenteration or a beyond total mesorectal excision (TME). The aim of this systematic review is to explore the safety and feasibility of robotic surgery in locally advanced and recurrent rectal cancer by evaluating perioperative outcomes, oncological clearance rates, and survival and recurrence rates postrobotic beyond TME surgery. METHODS: The systematic review will include studies published until the end of December 2023. The MEDLINE, EMBASE and Scopus databases will be searched. The screening process, study selection, data extraction, quality assessment and analysis will be performed by two independent reviewers. Discrepancies will be resolved by consensus with a third independent reviewer. The risk of bias will be assessed with validated scores. The primary outcomes will be oncological clearance, overall and disease-free survival, and local and systemic recurrence rates post robotic or robot-assisted beyond TME surgery for locally advanced or recurrent rectal cancer. Secondary outcomes will include perioperative outcomes. ETHICS AND DISSEMINATION: No ethical approval is required for this systematic review as no individual patient cases are studied requiring access to individual medical records. The results of the systematic review will be disseminated with conference presentations and peer-reviewed paper publications. PROSPERO REGISTRATION OF THE STUDY: CRD42023408098.

Perioperative and long-term oncological outcomes of robotic versus laparoscopic total mesorectal excision: a retrospective study of 672 patients.

Although there's growing information about the long-term oncological effects of robotic surgery for rectal cancer, the procedure is still relatively new. This study aimed to assess the long-term oncological results of total mesorectal excision (TME) performed laparoscopically versus robotically in the setting of rectal cancer. Restrospective analysis of a prospectively maintained database. A total of 489 laparoscopic (L-TME) and 183 robotic total mesorectal excisions (R-TME) were carried out by a single surgeon between 2013 and 2023. The groups were compared in terms of perioperative and long-term oncological outcomes. In the R-TME and L-TME groups, male sex predominated (75.4% and 57.3%, respectively), although the robotic group was significantly greater (p = 0.008). There was no conversion in R-TME group, whereas three (0.6%) converted to open surgery in L-TME group. The R-TME group had a statistically significant higher number of distal rectal tumors (85%) compared to the L-TME group (54.6%). Only three (1.7%) patients in the R-TME group received abdomineperineal resection (APR); in contrast, 25 (5%) patients in the L-TME group received APR (p < 0.001). For R-TME, the mean follow-up was 70.7 months (range 18-138) and for L-TME, it was 60 months (range 14-140). Frequency of completed mesorectum was significantly greater in R-TME group (98.9% vs 94.2%, p < 0.001). The 5 year overall survival rates for R-TME and L-TME groups were 89.6% and 88.7%, respectively. The 5 year disease-free survival for R-TME and L-TME groups were 84.1% and 81.1%, respectively. The local recurrences rates were 7.6% and 6.3%, respectively in R-TME and L-TME groups (p = 0.274). R-TME is characterized by no conversion and improved mesorectal integrity. R-TME had longer operation time. The long-term oncological outcomes were comparable between groups.

Detection and Real-Time Surgical Assessment of Colorectal Liver Metastases Using Near-Infrared Fluorescence Imaging during Laparoscopic and Robotic-Assisted Resections.

BACKGROUND: The European Association of Endoscopic Surgery (EAES) recommends, with strong evidence, the use of indocyanine green (ICG) fluorescence imaging combined with intraoperative ultrasound (IOUS) to improve identification of superficial liver tumors. This study reports the use of ICG for the detection of colorectal liver metastases (CRLMs) during minimally invasive liver resection. METHODS: A single-center consecutive series of minimally invasive (laparoscopic and robotic) hepatic resections for CRLMs was prospectively evaluated (April 2019 and October 2023). RESULTS: A total of 25 patients were enrolled-11 undergoing laparoscopic and 14 undergoing robotic procedures. The median age was 65 (range 50-85) years. Fifty CRLMs were detected: twenty superficial, eight exophytic, seven shallow (<8 mm from the hepatic surface), and fifteen deep (>10 mm from the hepatic surface) lesions. The detection rates of CRLMs through preoperative imaging, laparoscopic ultrasound (LUS), ICG fluorescence, and combined modalities (ICG and LUS) were 88%, 90%, 68%, and 100%, respectively. ICG fluorescence staining allowed us to detect five small additional superficial lesions (not identified with other preoperative/intraoperative techniques). However, two lesions were false positive fluorescence accumulations. All rim fluorescence pattern lesions were CRLMs. ICG fluorescence was used as a real-time guide to assess surgical margins during parenchymal-sparing liver resections. All patients with integrity of the fluorescent rim around the CRLM displayed a radical resection during histopathological analysis. Four patients (8%) with a protruding rim or residual rim patterns had positive resection margins. CONCLUSIONS: ICG fluorescence imaging can be integrated with other conventional intraoperative imaging techniques to optimize intraoperative staging. Rim fluorescence proved to be a valid indicator of the resection margins: by removing the entire fluorescent area, a tumor-negative resection (R0) is achieved.