Free-Viewpoint Video in Open Surgery: Development of Surgical Arena 360.

OBJECTIVE: We aimed to apply the free-viewpoint video technology developed and introduced mainly for sports spectators to an open surgical video recording system. DESIGN: Prospective feasibility study. SETTING: University of Tsukuba Hospital, Ibaraki, Japan. PARTICIPANTS: Patients who underwent open pancreaticoduodenectomy for pancreatic cancer between December 2022 and March 2023 were included. The gastrojejunal anastomosis was the subject of the recording. RESULTS: Four surgeries were recorded with Surgical Arena 360, which is the free-viewpoint video system that we developed. The feasibility of performing a series of surgical procedures without interrupting the surgeon's line of sight or manipulation was demonstrated in all cases. CONCLUSIONS: Our study revealed that Surgical Arena 360, an open surgical video recording system developed by applying free-viewpoint video technology, can provide new insights into surgical support and clinical knowledge to surgeons by enabling secure capture of the open surgical field from multiple angles.

Intraoperative artificial intelligence system identifying liver vessels in laparoscopic liver resection: a retrospective experimental study.

BACKGROUND: The precise recognition of liver vessels during liver parenchymal dissection is the crucial technique for laparoscopic liver resection (LLR). This retrospective feasibility study aimed to develop artificial intelligence (AI) models to recognize liver vessels in LLR, and to evaluate their accuracy and real-time performance. METHODS: Images from LLR videos were extracted, and the hepatic veins and Glissonean pedicles were labeled separately. Two AI models were developed to recognize liver vessels: the "2-class model" which recognized both hepatic veins and Glissonean pedicles as equivalent vessels and distinguished them from the background class, and the "3-class model" which recognized them all separately. The Feature Pyramid Network was used as a neural network architecture for both models in their semantic segmentation tasks. The models were evaluated using fivefold cross-validation tests, and the Dice coefficient (DC) was used as an evaluation metric. Ten gastroenterological surgeons also evaluated the models qualitatively through rubric. RESULTS: In total, 2421 frames from 48 video clips were extracted. The mean DC value of the 2-class model was 0.789, with a processing speed of 0.094 s. The mean DC values for the hepatic vein and the Glissonean pedicle in the 3-class model were 0.631 and 0.482, respectively. The average processing time for the 3-class model was 0.097 s. Qualitative evaluation by surgeons revealed that false-negative and false-positive ratings in the 2-class model averaged 4.40 and 3.46, respectively, on a five-point scale, while the false-negative, false-positive, and vessel differentiation ratings in the 3-class model averaged 4.36, 3.44, and 3.28, respectively, on a five-point scale. CONCLUSION: We successfully developed deep-learning models that recognize liver vessels in LLR with high accuracy and sufficient processing speed. These findings suggest the potential of a new real-time automated navigation system for LLR.

Deep learning-based vessel automatic recognition for laparoscopic right hemicolectomy.

BACKGROUND: In laparoscopic right hemicolectomy (RHC) for right-sided colon cancer, accurate recognition of the vascular anatomy is required for appropriate lymph node harvesting and safe operative procedures. We aimed to develop a deep learning model that enables the automatic recognition and visualization of major blood vessels in laparoscopic RHC. MATERIALS AND METHODS: This was a single-institution retrospective feasibility study. Semantic segmentation of three vessel areas, including the superior mesenteric vein (SMV), ileocolic artery (ICA), and ileocolic vein (ICV), was performed using the developed deep learning model. The Dice coefficient, recall, and precision were utilized as evaluation metrics to quantify the model performance after fivefold cross-validation. The model was further qualitatively appraised by 13 surgeons, based on a grading rubric to assess its potential for clinical application. RESULTS: In total, 2624 images were extracted from 104 laparoscopic colectomy for right-sided colon cancer videos, and the pixels corresponding to the SMV, ICA, and ICV were manually annotated and utilized as training data. SMV recognition was the most accurate, with all three evaluation metrics having values above 0.75, whereas the recognition accuracy of ICA and ICV ranged from 0.53 to 0.57 for the three evaluation metrics. Additionally, all 13 surgeons gave acceptable ratings for the possibility of clinical application in rubric-based quantitative evaluations. CONCLUSION: We developed a DL-based vessel segmentation model capable of achieving feasible identification and visualization of major blood vessels in association with RHC. This model may be used by surgeons to accomplish reliable navigation of vessel visualization.

Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy versus R0 resection for resectable colorectal cancer with peritoneal metastases and low peritoneal cancer index scores: a collaborative observational study from Korea and Japan.

BACKGROUND: The benefits of hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreductive surgery (CRS) for colorectal cancer with peritoneal metastasis (CPM) remain controversial. R0 resection without peritoneal stripping might be as effective as CRS plus HIPEC. The authors aimed to compare the long-term oncological outcomes of patients with CPM and peritoneal cancer index (PCI) scores less than or equal to 6 who underwent R0 resection in Japan with those who underwent CRS plus HIPEC in Korea. MATERIALS AND METHODS: This international, retrospective cohort study was conducted in Korea and Japan using a prospectively collected clinical database. Patients who underwent surgery from July 2014 to December 2021 for CPM with a PCI score of less than or equal to 6 and completeness of the cytoreduction score-0 were included. The primary outcome was relapse-free survival (RFS), and the secondary outcomes were overall survival, peritoneal RFS (PRFS), and postoperative outcomes. RESULTS: The 3-year RFS was significantly longer in the CRS+HIPEC group than in the R0 resection group: 35.9% versus 6.9% ( P <0.001); 31.0% versus 6.7% ( P =0.040) after propensity score matching. The median PRFS was significantly longer in the CRS+HIPEC group than in the R0 resection group: 24.5 months versus 17.2 months ( P =0.017). The 3-year overall survival and postoperative complications did not significantly differ between the two groups. CONCLUSIONS: RFS and PRFS rates were significantly prolonged after CRS plus HIPEC, whereas postoperative complications and length of hospital stay were not increased. Therefore, curative CRS plus HIPEC may be considered a treatment strategy for selected patients with resectable CPM and low PCI scores.

Automatic surgical phase recognition-based skill assessment in laparoscopic distal gastrectomy using multicenter videos.

BACKGROUND: Gastric surgery involves numerous surgical phases; however, its steps can be clearly defined. Deep learning-based surgical phase recognition can promote stylization of gastric surgery with applications in automatic surgical skill assessment. This study aimed to develop a deep learning-based surgical phase-recognition model using multicenter videos of laparoscopic distal gastrectomy, and examine the feasibility of automatic surgical skill assessment using the developed model. METHODS: Surgical videos from 20 hospitals were used. Laparoscopic distal gastrectomy was defined and annotated into nine phases and a deep learning-based image classification model was developed for phase recognition. We examined whether the developed model's output, including the number of frames in each phase and the adequacy of the surgical field development during the phase of supra-pancreatic lymphadenectomy, correlated with the manually assigned skill assessment score. RESULTS: The overall accuracy of phase recognition was 88.8%. Regarding surgical skill assessment based on the number of frames during the phases of lymphadenectomy of the left greater curvature and reconstruction, the number of frames in the high-score group were significantly less than those in the low-score group (829 vs. 1,152, P < 0.01; 1,208 vs. 1,586, P = 0.01, respectively). The output score of the adequacy of the surgical field development, which is the developed model's output, was significantly higher in the high-score group than that in the low-score group (0.975 vs. 0.970, P = 0.04). CONCLUSION: The developed model had high accuracy in phase-recognition tasks and has the potential for application in automatic surgical skill assessment systems.

Can the Single-stapling Technique Following Intersphincteric Resection with Transanal Total Mesorectal Excision Become the New Standard Anastomosis?

For transanal total mesorectal excision (TaTME), the indication for single-stapling technique (SST) has been expanded to include lower anastomosis, even in intersphincteric resection (ISR). We focused on the anastomotic techniques following ISR with TaTME and examined the feasibility and safety of the SST below the anorectal junction (ARJ). Data on postoperative anastomosis-related complications and anorectal function was evaluated in comparison to conventional manual hand-sewn coloanal anastomosis in ISR with TaTME. We examined patients with 3-6 cm tumors from the anal verge who underwent ISR with TaTME between January 2018 and March 2020, and whose anastomotic line was located below the ARJ. Postoperative short-term outcomes and anorectal functions were compared. We also analyzed the effects of various factors on major low anterior resection syndrome (LARS) using multivariate logistic regression analysis. In total, 87 patients-48 in the hand-sewn anastomosis group and 39 in the SST group-were included in this study. SST below the ARJ in ISR with TaTME did not exacerbate surgical outcomes, including anastomosis-related complications. The SST group had a significantly lower LARS score as compared to the hand-sewn anastomosis group, and the proportion of major LARS was significantly lower. Only hand-sewn anastomosis was identified as a statistically significant independent risk factor for major LARS. In TaTME, SST below the ARJ was safe and feasible and had a lower negative impact on postoperative anastomosis-related complications and anorectal function as compared to hand-sewn anastomosis. Thus, SST is a promising anastomotic option for patients with low-lying rectal tumors.

Transanal Total Mesorectal Excision for Rectal Cancer: Toward Standardization of the Surgical Technique.

Laparoscopic surgery is widely used for rectal cancer; however, this technique is challenging due to tapering of the mesorectum in the pelvis, and the forward angle of the distal rectum, which renders this part of the rectum less accessible from the abdominal cavity. Hence, concerns regarding its safety and curability have been raised, particularly for inadequate distal and circumferential resection margins. Recently, transanal total mesorectal excision (TaTME), which involves endoscopic total mesorectal excision (TME) retrogradely from the anal side, has attracted attention worldwide as a solution to these problems. TaTME is superior to the conventional laparoscopic approach for rectal cancer in terms of both oncological and functional preservations. However, a shallow learning curve caused by the unfamiliar anatomical view from the anal side can pose challenges. Therefore, an efficient educational system needs to be established. Randomized controlled trials comparing conventional laparoscopic TME with TaTME are ongoing to demonstrate the usefulness of TaTME. This article reviews changes in the surgical treatment of rectal cancer, with a focus on TaTME, and describes the indications, surgical techniques, and training curricula for TaTME.

Risk factors for postoperative delirium in elderly patients undergoing gastroenterological surgery: A single-center retrospective study.

Aim: To investigate the risk factors for postoperative delirium among elderly patients undergoing elective surgery for gastroenterological cancer. Methods: From May 2020 to March 2022, patients ≥75 years old with gastroenterological cancer who underwent radical surgery were enrolled. The geriatric assessment, including evaluations of frailty, physical function, nutrition status, and cognitive function, was conducted preoperatively. The confusion assessment method was used to diagnose postoperative delirium. A multivariate logistic regression analysis was used to determine risk factors for postoperative delirium. Results: A total of 158 patients were eligible for inclusion in this study. Of these 53 patients (34%) developed postoperative delirium. In the univariate analysis, the age, regular use of sleeping drugs and benzodiazepine, Charlson Comorbidity Index score, performance status, Fried's frailty score, Vulnerable Elders Survey-13 score, grip weakness, Short Physical Performance Battery (SPPB) score, Mini Nutritional Assessment Short-Form score, and Mini-Mental State Examination score were statistically associated with the incidence of postoperative delirium. In the multivariate analysis, a SPPB score ≤9, Mini Nutritional Assessment score ≤11, a Mini-Mental State Examination score ≤24, and regular use of benzodiazepine were found to be independent preoperative risk factors for postoperative delirium. Conclusion: Certain findings during the preoperative geriatric assessment, especially low SPPB, Mini Nutritional Assessment Short-Form and Mini-Mental State Examination scores, and regular use of benzodiazepine were risk factors for postoperative delirium in elderly patients undergoing gastroenterological surgery.

Artificial intelligence for the recognition of key anatomical structures in laparoscopic colorectal surgery.

To prevent intraoperative organ injury, surgeons strive to identify anatomical structures as early and accurately as possible during surgery. The objective of this prospective observational study was to develop artificial intelligence (AI)-based real-time automatic organ recognition models in laparoscopic surgery and to compare its performance with that of surgeons. The time taken to recognize target anatomy between AI and both expert and novice surgeons was compared. The AI models demonstrated faster recognition of target anatomy than surgeons, especially novice surgeons. These findings suggest that AI has the potential to compensate for the skill and experience gap between surgeons.

Automatic Surgical Skill Assessment System Based on Concordance of Standardized Surgical Field Development Using Artificial Intelligence.

Importance: Automatic surgical skill assessment with artificial intelligence (AI) is more objective than manual video review-based skill assessment and can reduce human burden. Standardization of surgical field development is an important aspect of this skill assessment. Objective: To develop a deep learning model that can recognize the standardized surgical fields in laparoscopic sigmoid colon resection and to evaluate the feasibility of automatic surgical skill assessment based on the concordance of the standardized surgical field development using the proposed deep learning model. Design, Setting, and Participants: This retrospective diagnostic study used intraoperative videos of laparoscopic colorectal surgery submitted to the Japan Society for Endoscopic Surgery between August 2016 and November 2017. Data were analyzed from April 2020 to September 2022. Interventions: Videos of surgery performed by expert surgeons with Endoscopic Surgical Skill Qualification System (ESSQS) scores higher than 75 were used to construct a deep learning model able to recognize a standardized surgical field and output its similarity to standardized surgical field development as an AI confidence score (AICS). Other videos were extracted as the validation set. Main Outcomes and Measures: Videos with scores less than or greater than 2 SDs from the mean were defined as the low- and high-score groups, respectively. The correlation between AICS and ESSQS score and the screening performance using AICS for low- and high-score groups were analyzed. Results: The sample included 650 intraoperative videos, 60 of which were used for model construction and 60 for validation. The Spearman rank correlation coefficient between the AICS and ESSQS score was 0.81. The receiver operating characteristic (ROC) curves for the screening of the low- and high-score groups were plotted, and the areas under the ROC curve for the low- and high-score group screening were 0.93 and 0.94, respectively. Conclusions and Relevance: The AICS from the developed model strongly correlated with the ESSQS score, demonstrating the model's feasibility for use as a method of automatic surgical skill assessment. The findings also suggest the feasibility of the proposed model for creating an automated screening system for surgical skills and its potential application to other types of endoscopic procedures.

Short-term outcomes following intracorporeal vs. extracorporeal anastomosis after laparoscopic right and left-sided colectomy: a propensity score-matched study.

BACKGROUND: To compare the short-term outcomes of patients undergoing intracorporeal anastomosis (IA) during laparoscopic colectomy to those undergoing extracorporeal anastomosis (EA). METHODS AND MATERIALS: The study was a single-centre retrospective propensity score-matched analysis conducted. Consecutive patients who underwent elective laparoscopic colectomy without the double stapling technique between January 2018 and June 2021 were investigated. The main outcome was overall postoperative complications within 30 days after the procedure. The authors also performed a sub-analysis of the postoperative results of ileocolic anastomosis and colocolic anastomosis, respectively. RESULTS: A total of 283 patients were initially extracted; after propensity score matching, there were 113 patients in each of the IA and EA groups. There were no differences in patient characteristics between the two groups. The IA group had a significantly longer operative time than the EA group (208 vs. 183 min, P =0.001). The rate of overall postoperative complications was significantly lower in the IA group ( n =18, 15.9%) than in the EA group ( n =34, 30.1%; P =0.02), especially in colocolic anastomosis after left-sided colectomy (IA: 23.8% vs. EA: 59.1%; P =0.03). Postoperative inflammatory marker levels were significantly higher in the IA group on postoperative day 1 but not on postoperative day 7. There was no difference in the postoperative lengths of hospital stay between the two groups, and no deaths occurred. CONCLUSION: The data suggest that performing IA during laparoscopic colectomy can potentially reduce the risk of postoperative complications, especially in colocolic anastomosis after left-sided colectomy.

Survival outcomes following salvage abdominoperineal resection for recurrent and persistent anal squamous cell carcinoma.

INTRODUCTION: The primary treatment for locoregional failure following chemoradiotherapy for squamous cell carcinoma of the anus (SCCA) is salvage abdominoperineal resection (APR). However, it is necessary to distinguish between recurrent and persistent diseases because of their varied pathologies. We aimed to clarify the survival outcomes following salvage APR for recurrent and persistent diseases and investigate the significance of salvage APR. MATERIALS AND METHODS: This multicentre retrospective cohort study used clinical data from 47 hospitals. All patients were diagnosed with SCCA and underwent definitive radiotherapy as the primary treatment between 1991 and 2015. Overall survival (OS) was compared between the following cohorts: salvage APR for recurrence, salvage APR for persistence, non-salvage APR for recurrence, and non-salvage APR for persistence. RESULTS: Five-year OS of salvage APR for recurrence, salvage APR for persistence, non-salvage APR for recurrence, and non-salvage APR for persistence were 75% (46%-90%), 36% (21%-51%), 42% (21%-61%), and 47% (33%-60%), respectively. OS of salvage APR for the recurrent disease was significantly higher than that for persistent disease (p = 0.00597). For recurrent disease, OS following salvage APR was significantly higher than that following non-salvage APR (p = 0.0204); however, for persistent disease, there was no significant difference between salvage and non-salvage APR (p = 0.928). CONCLUSION: Survival outcomes following salvage APR for persistent disease were significantly worse than that for recurrent disease. Salvage APR did not improve survival outcomes for persistent disease compared to non-salvage APR. These results will elicit a review of persistent disease treatment strategies.

A comparative study of stoma-related complications from diverting loop ileostomy or colostomy after colorectal surgery.

PURPOSE: Even though minor, stoma-related complications significantly impact quality of life, they are often excluded from clinical analyses that compare short-term postoperative outcomes of loop ileostomy and loop colostomy. This study compares stoma-related complications between loop ileostomy and loop colostomy after rectal resection, including minor complications, and discusses the characteristics of diverting stoma types. METHODS: A retrospective review was conducted in patients who underwent diverting stoma construction after rectal resection. Data on patient background and postoperative short-term outcomes, including stoma-related complications and morbidity after stoma closure, were collected and compared between loop ileostomy and loop colostomy groups. Morbidities of all severity grades were targeted for analysis. RESULTS: A total of 47 patients (27 loop ileostomy, 20 loop colostomy) underwent diverting stoma construction following rectal resection. Overall stoma-related complications, incidence of skin irritation, high-output stoma, and outlet obstruction were significantly higher in the loop ileostomy group but high-output stoma and outlet obstruction were absent in the loop colostomy group. Regarding morbidity after stoma closure, operation times and surgical site infections were significantly higher in the loop colostomy group while anastomotic leakage after diverting stoma closure occurred (2 cases; 15%) in the loop colostomy group but not the loop ileostomy group. CONCLUSION: Because stoma-related complications were significantly higher in the loop ileostomy group, and even these minor complications may impair QOL, early loop ileostomy closure is recommended. For loop colostomy, stoma-related morbidities are lower but post-closure leakage is a calculated risk.

Automatic purse-string suture skill assessment in transanal total mesorectal excision using deep learning-based video analysis.

BACKGROUND: Purse-string suture in transanal total mesorectal excision is a key procedural step. The aims of this study were to develop an automatic skill assessment system for purse-string suture in transanal total mesorectal excision using deep learning and to evaluate the reliability of the score output from the proposed system. METHODS: Purse-string suturing extracted from consecutive transanal total mesorectal excision videos was manually scored using a performance rubric scale and computed into a deep learning model as training data. Deep learning-based image regression analysis was performed, and the purse-string suture skill scores predicted by the trained deep learning model (artificial intelligence score) were output as continuous variables. The outcomes of interest were the correlation, assessed using Spearman's rank correlation coefficient, between the artificial intelligence score and the manual score, purse-string suture time, and surgeon's experience. RESULTS: Forty-five videos obtained from five surgeons were evaluated. The mean(s.d.) total manual score was 9.2(2.7) points, the mean(s.d.) total artificial intelligence score was 10.2(3.9) points, and the mean(s.d.) absolute error between the artificial intelligence and manual scores was 0.42(0.39). Further, the artificial intelligence score significantly correlated with the purse-string suture time (correlation coefficient = -0.728) and surgeon's experience (P< 0.001). CONCLUSION: An automatic purse-string suture skill assessment system using deep learning-based video analysis was shown to be feasible, and the results indicated that the artificial intelligence score was reliable. This application could be expanded to other endoscopic surgeries and procedures.

Deep-learning-based semantic segmentation of autonomic nerves from laparoscopic images of colorectal surgery: an experimental pilot study.

BACKGROUND: The preservation of autonomic nerves is the most important factor in maintaining genitourinary function in colorectal surgery; however, these nerves are not clearly recognisable, and their identification is strongly affected by the surgical ability. Therefore, this study aimed to develop a deep learning model for the semantic segmentation of autonomic nerves during laparoscopic colorectal surgery and to experimentally verify the model through intraoperative use and pathological examination. MATERIALS AND METHODS: The annotation data set comprised videos of laparoscopic colorectal surgery. The images of the hypogastric nerve (HGN) and superior hypogastric plexus (SHP) were manually annotated under a surgeon's supervision. The Dice coefficient was used to quantify the model performance after five-fold cross-validation. The model was used in actual surgeries to compare the recognition timing of the model with that of surgeons, and pathological examination was performed to confirm whether the samples labelled by the model from the colorectal branches of the HGN and SHP were nerves. RESULTS: The data set comprised 12 978 video frames of the HGN from 245 videos and 5198 frames of the SHP from 44 videos. The mean (±SD) Dice coefficients of the HGN and SHP were 0.56 (±0.03) and 0.49 (±0.07), respectively. The proposed model was used in 12 surgeries, and it recognised the right HGN earlier than the surgeons did in 50.0% of the cases, the left HGN earlier in 41.7% of the cases and the SHP earlier in 50.0% of the cases. Pathological examination confirmed that all 11 samples were nerve tissue. CONCLUSION: An approach for the deep-learning-based semantic segmentation of autonomic nerves was developed and experimentally validated. This model may facilitate intraoperative recognition during laparoscopic colorectal surgery.

Two-team lateral lymph node dissection assisted by the transanal approach for locally advanced lower rectal cancer: comparison with the conventional transabdominal approach.

BACKGROUND: An optimal surgical approach to lateral lymph node dissection (LLND) remains controversial. With the recent popularity of transanal total mesorectal excision, a two-team procedure combining the transabdominal and transanal approaches was established as a novel approach to LLND. This study aimed to clarify the safety and feasibility of two-team LLND (2team-LLND) and compare its short-term outcomes with those of conventional transabdominal LLND (Conv-LLND). METHODS: Between April 2013 and March 2020, 463 patients diagnosed with primary locally advanced rectal cancer underwent a transanal total mesorectal excision; among them, 93 patients who underwent bilateral prophylactic LLND were included in this single-center, retrospective study. Among these patients, 50 and 43 patients underwent Conv-LLND (the Conv-LLND group) and 2team-LLND (the 2team-LLND group), respectively. The short-term outcomes, including the operation time, blood loss volume, number of complications, and number of harvested lymph nodes, were compared between the two groups. RESULTS: The intraoperative and postoperative complications in the 2team-LLND group were equivalent to those in the Conv-LLND group; furthermore, the incidence of postoperative urinary retention in the 2team-LLND group was acceptably low (9%). Compared with the Conv-LLND group, the 2team-LLND group had a significantly shorter operation time (P = 0.003), lower median blood loss (P = 0.02), and higher number of harvested lateral lymph nodes (P = 0.0005). CONCLUSION: The intraoperative and postoperative complications of 2team-LLND were comparable with those of Conv-LLND. Thus, 2team-LLND was safe and feasible for advanced lower rectal cancer. Moreover, it was superior to Conv-LLND in terms of the operation time, blood loss volume, and number of harvested lateral lymph nodes. Therefore, it can be a promising LLND approach.

Single-center comparative study of short-term outcomes of transanal and laparoscopic total mesorectal excisions for low and middle rectal cancers.

BACKGROUND: Transanal total mesorectal excision is a promising surgical treatment for rectal cancer. However, evidence regarding the differences in outcomes between the transanal and laparoscopic total mesorectal excisions is scarce. We compared the short-term outcomes of transanal and laparoscopic total mesorectal excisions for low and middle rectal cancers. METHODS: This retrospective study included patients who underwent low anterior or intersphincteric resection for middle (5-10 cm) or low (< 5 cm) rectal cancer at the National Cancer Center Hospital East, Japan, from May 2013 to March 2020. Primary rectal adenocarcinoma was confirmed histologically. Circumferential resection margins (CRMs) of resected specimens were measured; margins ≤ 1 mm were considered positive. The operative time, blood loss, hospitalization length, postoperative readmission rate, and short-term treatment results were compared. RESULTS: Four hundred twenty-nine patients were divided into two mesorectal excision groups: transanal (n = 295) and laparoscopic (n = 134). Operative times were significantly shorter in the transanal group than in the laparoscopic group (p < 0.001). The pathological T stage and N status were not significantly different. The transanal group had significantly lower positive CRM rates (p = 0.04), and significantly lower incidence of the Clavien-Dindo grade III (p = 0.02) and IV (p = 0.03) complications. Both groups had distal margin positivity rates of 0%. CONCLUSIONS: Compared to laparoscopic, transanal total mesorectal excision for low and middle rectal cancers has lower incident postoperative complication and CRM-positivity rates, demonstrating the safety and usefulness of local curability for middle and low rectal cancers.

Single-stapling technique versus hand-sewn anastomosis in inter-sphincteric resection with transanal total mesorectal excision (Super SST): protocol for a multicentre randomized clinical trial.

BACKGROUND: Currently, hand-sewn anastomosis is the standard procedure for inter-sphincteric resection (ISR); however, distal purse-string suturing during transanal total mesorectal excision (TaTME) has allowed a single-stapling technique (SST). Although it was originally intended for cases requiring anastomosis of 2 cm or more above the anorectal junction (ARJ), SST could be safely performed in ISR. The aim of this trial is to determine the superiority of SST over hand-sewn anastomosis in ISR with TaTME. METHODS: The Super SST trial is a multicentre randomized clinical trial comparing stapled and hand-sewn anastomoses in ISR with TaTME. The trial will recruit patients scheduled for TaTME with anastomosis below the ARJ, who will be allocated 1:1 to receive either hand-sewn or stapled anastomosis. The primary endpoint is anastomosis-related complications within 30 postoperative days. Secondary endpoints include all early and late complications, operating time, reoperation, mortality rate, length of postoperative hospital stay, readmission, incidence of anal pain and rectal mucosal prolapse, length of temporary stoma retention, the proportion of patients with a temporary stoma at 1 year after surgery, and anorectal function at 1 year after surgery. CONCLUSION: This trial will provide important clinical insights for new and promising anastomotic options for patients with very low rectal cancer. Registration number: UMIN000047818 (https://www.umin.ac.jp/ctr/index-j.htme).