The short-term outcomes of robotic sphincter-preserving surgery for rectal cancer: comparison with open and laparoscopic surgery using a propensity score analysis

Robotic surgery is associated with a decreased risk of circumferential resection margin positivity compared with conventional laparoscopic surgery in patients with rectal cancer undergoing mesorectal excision: A systematic review and meta-analysis

OBJECTIVE

To investigate whether robotic surgery (RS) decreases the risk of circumferential resection margin (CRM) positivity compared with conventional laparoscopic surgery (LS) in patients with rectal cancer (RC) undergoing mesorectal excision (ME).

BACKGROUND

Although it is well known that CRM positivity affects postoperative outcomes in patients with RC undergoing ME, few studies have investigated whether RS is superior to conventional LS for the risk of CRM positivity.

METHODS

We performed a comprehensive electronic search of the literature up to December 2022 to identify studies that compared the risk of CRM positivity between patients with RC undergoing robotic and conventional laparoscopic surgery. A meta-analysis was performed using random-effects models to calculate risk ratios (RRs) and 95 % confidence intervals (CIs), and heterogeneity was analyzed using I2 statistics.

RESULTS

Eighteen studies, consisting of 4 randomized controlled trials (RCTs) and 14 propensity score matching (PSM) studies, involved a total of 9203 patients with RC who underwent ME were included in this meta-analysis. The results demonstrated that RS decreased the overall risk of CRM positivity (RR, 0.82; 95 % CI, 0.73-0.92; P = 0.001; I2 = 0 %) compared with conventional LS. Results of a meta-analysis of the 4 selected RCTs also showed that RS decreased the risk of CRM positivity (RR, 0.62; 95 % CI, 0.43-0.91; P = 0.01; I2 = 0 %) compared with conventional LS.

CONCLUSIONS

This meta-analysis revealed that RS is associated with a decreased risk of CRM positivity compared with conventional LS in patients with RC undergoing ME.

The role of robotic-assisted surgery in the management of rectal cancer: a systematic review and meta-analysis

BACKGROUND

Rectal cancer poses a significant global health burden. There is a lack of concrete evidence concerning the benefits of robotic-assisted surgery (RAS) for rectal cancer surgery as compared to laparoscopic and open techniques. To address this gap, we conducted a meta-analysis to assess the intraoperative, postoperative, and safety outcomes of robotic surgery in this context.

RESEARCH METHODOLOGY

A search of MEDLINE, Scopus and the Cochrane Library. Randomized and non-randomized studies up to February 2, 2024 comparing robotic surgery versus laparoscopic or open surgery for rectal cancer. The outcomes of interest were operative time, blood loss, harvested lymph nodes, conversion rate, postoperative hospital stay, survival to hospital discharge, urinary retention rate, and anastomotic leakage rate. A random-effects meta-analysis was performed to pool means and dichotomous data to derive weighted mean differences and odds ratios, respectively.

RESULTS

A total of 56 studies were shortlisted after the study selection process with a total of 25 458 rectal cancer patients. From the intraoperative outcomes, RAS was significantly associated with an increased operative time (WMD: 41.04, P <0.00001), decreased blood loss (WMD: -24.56, P <0.00001), decreased conversion rates (OR: 0.39, P <0.00001), lesser stay at the hospital (WMD: -1.93, P <0.00001), and no difference was found in lymph nodes harvested. Similarly, RAS group had a significantly greater survival to hospital discharge (OR: 1.90, P =0.04), decreased urinary retention rate (OR: 0.59, P =0.002), and no difference was seen in anastomotic leakage rate.

CONCLUSION

RAS demonstrates favorable outcomes for rectal cancer patients, contributing to global prevention and control efforts, health promotion, and addressing non-communicable disease risk factors. Further research and public awareness are needed to optimize RAS utilization in this context.

Learning curve of robotic rectal surgery using risk-adjusted cumulative summation: a 5-year institutional experience

PURPOSE

Outline learning phases of robot-assisted laparoscopic surgery for rectal cancer and compare surgical and clinical outcomes between each phase of robot-assisted laparoscopic surgery and the mastery phase of conventional laparoscopic surgery.

METHODS

From 2015 to 2020, 210 patients underwent rectal cancer surgery at Sendai Medical Center. We performed conventional laparoscopic surgery in 110 patients and, laparoscopic surgery in 100 patients. The learning curve was evaluated using the cumulative summation method, risk-adjusted cumulative summation method, and logistic regression analysis.

RESULTS

The risk-adjusted cumulative summation learning curve was divided into three phases: phase 1 (cases 1-48), phase 2 (cases 49-80), and phase 3 (cases 81-100). Duration of hospital stay (13.1 days vs. 18.0 days, respectively; p = 0.016) and surgery (209.1 min vs. 249.5 min, respectively; p = 0.045) were significantly shorter in phase 3 of the robot-assisted laparoscopic surgery group than in the conventional laparoscopic surgery group. Blood loss volume was significantly lower in phase 1 of the robot-assisted laparoscopic surgery group than in the conventional laparoscopic surgery group (17.7 ml vs. 79.7 ml, respectively; p = 0.036). The International Prostate Symptom Score was significantly lower in the robot-assisted laparoscopic surgery group (p = 0.0131).

CONCLUSIONS

Robot-assisted laparoscopic surgery for rectal cancer was safe and demonstrated better surgical and clinical outcomes, including a shorter hospital stay, less blood loss, and a shorter surgical duration, than conventional laparoscopic surgery. After experience with at least 80 cases, tactile familiarity can be acquired from visual information only (visual haptic feedback).

CLINICAL TRIAL REGISTRATION

UMIN reference no. UMIN000019857.

Surgical outcomes of robotic, laparoscopic, and open low anterior resection after preoperative chemoradiotherapy for patients with advanced lower rectal cancer

PURPOSE

We investigated the surgical outcomes of robotic low anterior resection (LAR) for lower rectal cancer after preoperative chemoradiotherapy (pCRT).

METHODS

A total of 175 patients with lower rectal cancer who underwent LAR after pCRT between 2005 and 2020 were stratified into open (OS, n = 65), laparoscopic (LS, n = 64), and robotic surgery (RS, n = 46) groups. We compared the clinical, surgical, and pathological results among the three groups.

RESULTS

The RS and LS groups had less blood loss than the OS group (p < 0.0001). The operating time in the RS group was longer than in the LS and OS groups (p < 0.0001). The RS group had a significantly longer mean distal margin than the LS and OS groups (25.4 mm vs. 20.7 mm and 20.3 mm, respectively; p = 0.026). There was no significant difference in the postoperative complication rate among the groups. The local recurrence rate in the RS group was comparable to those in the LS and OS groups.

CONCLUSION

Robotic LAR after pCRT was performed safely for patients with advanced lower rectal cancer. It provided a longer distal margin and equivalent local control rates.

Analysis of bowel function, urogenital function, and long-term follow-up outcomes associated with robotic and laparoscopic sphincter-preserving surgical approaches to total mesorectal excision in low rectal cancer: a retrospective cohort study

OBJECTIVE

The present study comparatively analyzed short-term clinical effectiveness and long-term follow-up endpoints associated with robotic-assisted sphincter-preserving surgery (RAS) and laparoscopic-assisted sphincter-preserving surgery (LAS) when used to treat low rectal cancer.

METHOD

Within such a single-center retrospective cohort analysis, low rectal cancer patients that underwent RAS (n=200) or LAS (n=486) between January 2015 and beginning of July 2018 were enrolled.

RESULTS

The mean operative durations in the RAS and LAS cohorts were 249±64 min and 203±47 min, respectively (P<0.001). Temporary ileostomy rates in the RAS and LAS cohorts were 64.5% and 51.6% (P = 0.002). In addition, major variations across such cohorts regarding catheter removal timing, time to liquid intake, time to first leaving bed, and length of hospitalization (all P<0.001). This distal resection margin distance within the RAS cohort was diminished in comparison to LAS cohort (P=0.004). For patients within the LAS cohort, the time required to recover from reduced urinary/female sexual function was > 6 months post-surgery (P<0.0001), whereas within the RAS cohort this interval was 3 months (P<0.0001). At 6 months post-surgery, male sexual function within RAS cohort was improved in comparison to LAS cohort (P<0.001). At 6 months post-surgery, Wexner scores revealed similar results (P<0.001). No major variations within overall or disease-free survival were identified across these cohorts at 3 or 5 years post-surgery.

CONCLUSION

Robotic sphincter-preserving surgery is a safe and effective surgical technique in low rectal patients in terms of postoperative oncological safety and long-term endpoints. And the RAS strategy provides certain additional benefits with respect to short-term urogenital/anorectal functional recovery in treated patients compared to LAS.

Robotic-Assisted vs. Standard Laparoscopic Surgery for Rectal Cancer Resection: A Systematic Review and Meta-Analysis of 19,731 Patients

Simple Summary

Surgery remains a mainstay of combined modality treatment at patients with rectal cancer; however, there is a growing interest in using laparoscopic techniques (LG); including robotic-assisted techniques (RG). Therefore, we have prepared a meta-analysis of the literature regarding the safety and efficacy of robotic versus laparoscopic approaches in patients undergoing curative surgery for rectal cancer. The results indicate a number of advantages of RG in terms of both safety and efficacy. Operative time in the RG group was shorter and associated with a statistically significantly lower conversion of the procedure to open surgery. RG technique provided a shorter duration of hospital stay and lowered urinary risk retention. No differences were found between these techniques regarding TNM stage; N stage or lymph nodes harvested. Survival to hospital discharge or 30-day overall survival rate was 99.6% in RG vs. 98.8% for LG.

Abstract

Robotic-assisted surgery is expected to have advantages over standard laparoscopic approach in patients undergoing curative surgery for rectal cancer. PubMed, Cochrane Library, Web of Science, Scopus and Google Scholar were searched from database inception to 10 November 2021, for both RCTs and observational studies comparing robotic-assisted versus standard laparoscopic surgery for rectal cancer resection. Where possible, data were pooled using random effects meta-analysis. Forty-Two were considered eligible for the meta-analysis. Survival to hospital discharge or 30-day overall survival rate was 99.6% for RG and 98.8% for LG (OR = 2.10; 95% CI: 1.00 to 4.43; p = 0.05). Time to first flatus in the RG group was 2.5 ± 1.4 days and was statistically significantly shorter than in LG group (2.9 ± 2.0 days; MD = −0.34; 95%CI: −0.65 to 0.03; p = 0.03). In the case of time to a liquid diet, solid diet and bowel movement, the analysis showed no statistically significant differences (p > 0.05). Length of hospital stay in the RG vs. LG group varied and amounted to 8.0 ± 5.3 vs. 9.5 ± 10.0 days (MD = −2.01; 95%CI: −2.90 to −1.11; p < 0.001). Overall, 30-days complications in the RG and LG groups were 27.2% and 19.0% (OR = 1.11; 95%CI: 0.80 to 1.55; p = 0.53), respectively. In summary, robotic-assisted techniques provide several advantages over laparoscopic techniques in reducing operative time, significantly lowering conversion of the procedure to open surgery, shortening the duration of hospital stay, lowering the risk of urinary retention, improving survival to hospital discharge or 30-day overall survival rate.

Robotic and robotic-assisted vs laparoscopic rectal cancer surgery: A meta-analysis of short-term and long-term results

The usage of robotic surgery in rectal cancer (RC) is increasing, but there is an ongoing debate as to whether it provides any benefit. This study conducted a meta-analysis of rectal cancer surgery for short-term and long-term outcome by Robotic and robotic-assisted surgery (RS) vs laparoscopic surgery (LS).Pubmed, Embase, Ovid, CNKI, Cochrane Library and Web of Science databases were searched. Studies clearly documenting a comparison of short-term and long-term effect between RS and LS for RC were selected. Lymph node harvested, operation time, hospital stay, circumferential resection margins（CRM), complications, 3-year disease-free survival (DFS) and 5-year DFS parameters were evaluated. All data were performed by Review Manager 5.3 software. Nine studies were collected that included 1436 cases in total, 716 (49.86%) in the RS group, 720(50.14%) in the LS group. Compared with LS, RS was associated with longer operation time (MD 35.19, 95%CI [7.57, 62.81]; P = 0.01), but similar hospital stay (MD -0.43, 95%CI [-0.87,0.01]; P = 0.05).Lymph node harvested, CRM, complications, 3-year DFS, 5-year DFS had no significance difference between RS and LS groups（MD -0.67，95%CI[-1.53，0.19]；P = 0.13；MD 0.86，95%CI[0.54,1.37]；P = 0.52；MD 0.97，95%CI [0.73,1.29]；P = 0.86；MD 0.94，95%CI[0.60,1.48]；P = 0.79；MD 0.88，95%CI[0.52,1.47]；P = 0.61 respectively）.RS is feasible and safe for RC. It has an advantage in short -term outcome and a similar effect in long-term outcome compared with LS.

Robotic Surgery in Rectal Cancer

Rectal cancer is an important cause of morbidity and mortality worldwide. The most effective and curative treatment is surgery, and the standard procedure is total mesorectal excision, initially performed by open surgery and posteriorly by minimally invasive techniques. Robotic surgery is an emerging technology that is expected to overcome the limitations of the laparoscopic approach. It has several advantages, including a stable camera platform with high definition three-dimensional image, flexible instruments with seven degrees of freedom, a third arm for fixed retraction, fine motion scaling, excellent dexterity, ambidextrous capability, elimination of physiological tremors and better ergonomics, that facilitate a steady and precise tissue dissection. The main technical disadvantages are the loss of tactile sensation and tensile feedback and the complex installation process. The aim of the present study is to review the importance and benefits of robotic surgery in rectal cancer, particularly in comparison with the laparoscopic approach. Intraoperative estimated blood loss, short and long-term outcomes as well as pathological outcomes were similar between robotic and laparoscopic surgery. The operative time is usually longer in robotic surgery and the high costs are still its major drawback. Robotic surgery for rectal cancer demonstrated lower conversion rate to open surgery and benefits in urinary and sexual functions and has been established as a safe and feasible technique.

Potential urinary function benefits of initial robotic surgery for rectal cancer in the introductory phase

We aimed to evaluate the advantages and disadvantages of initial robotic surgery for rectal cancer in the introduction phase. This study retrospectively evaluated patients who underwent initial robotic surgery (n = 36) vs. patients who underwent conventional laparoscopic surgery (n = 95) for rectal cancer. We compared the clinical and pathological characteristics of patients using a propensity score analysis and clarified short-term outcomes, urinary function, and sexual function at the time of robotic surgery introduction. The mean surgical duration was longer in the robot-assisted laparoscopy group compared with the conventional laparoscopy group (288.4 vs. 245.2 min, respectively; p = 0.051). With lateral pelvic lymph node dissection, no significant difference was observed in surgical duration (508.0 min for robot-assisted laparoscopy vs. 480.4 min for conventional laparoscopy; p = 0.595). The length of postoperative hospital stay was significantly shorter in the robot-assisted laparoscopy group compared with the conventional laparoscopy group (15 days vs. 13.0 days, respectively; p = 0.026). Conversion to open surgery was not necessary in either group. The International Prostate Symptom Score was significantly lower in the robot-assisted laparoscopy group compared with the conventional laparoscopy group. Moderate-to-severe symptoms were more frequently observed in the conventional laparoscopy group compared with the robot-assisted laparoscopy group (p = 0.051). Robotic surgery is safe and could improve functional disorder after rectal cancer surgery in the introduction phase. This may depend on the surgeon’s experience in performing robotic surgery and strictly confined criteria in Japan.

State of the art in robotic rectal surgery: marginal gains worth the pain?

After their first introduction in the 1990s to overcome the limitations of conventional laparoscopic surgery, especially in confined spaces such as the pelvis, telemanipulators (i.e., master-slave manipulators) have gained popularity and acceptance among gastrointestinal surgeons. These complex, interventional surgical devices use multiple technologies, such as 3-D advanced imaging, tremor reduction and 7-degree movement. Superior instrument dexterity, stable precise vision and accessibility to narrow confined spaces make these devices well suited for colorectal surgery. The drive for innovations in the field of surgical robotics will leverage novel robots driven by data, image integration, and artificial intelligence. However, if this vision is to be realized, lessons must be learned from the current literature and clinical trials. The feasibility and safety of robotic rectal surgery is now well established; increasing evidence suggests that when compared to laparoscopic rectal surgery, robotic approaches might offer superior peri-operative outcomes. Notably, the marginal gains achieved with the use of robotics in rectal cancer surgery are linked with structured training and standardization of operative techniques. With decreasing costs and wider availability of new systems, it is foreseeable that robotic surgical systems will be an integral part of colorectal practice.

Comparison of pathologic outcomes of robotic and open resections for rectal cancer: A systematic review and meta-analysis

Objective

The application of robotic surgery for rectal cancer is increasing steadily. The purpose of this meta-analysis is to compare pathologic outcomes among patients with rectal cancer who underwent open rectal surgery (ORS) versus robotic rectal surgery (RRS).

Methods

We systematically searched the literature of EMBASE, PubMed, the Cochrane Library of randomized controlled trials (RCTs) and nonrandomized controlled trials (nRCTs) comparing ORS with RRS.

Results

Fourteen nRCTs, including 2711 patients met the predetermined inclusion criteria and were included in the meta-analysis. Circumferential resection margin (CRM) positivity (OR: 0.58, 95% CI, 0.29 to 1.16, P = 0.13), number of harvested lymph nodes (WMD: −0.31, 95% CI, −2.16 to 1.53, P = 0.74), complete total mesorectal excision (TME) rates (OR: 0.93, 95% CI, 0.48 to 1.78, P = 0.83) and the length of distal resection margins (DRM) (WMD: −0.01, 95% CI, −0.26 to 0.25, P = 0.96) did not differ significantly between the RRS and ORS groups.

Conclusion

Based on the current evidence, robotic resection for rectal cancer provided equivalent pathological outcomes to ORS in terms of CRM positivity, number of harvested lymph nodes and complete TME rates and DRM.

Outcomes of Minimally Invasive Versus Open Proctectomy for Rectal Cancer: A Propensity-Matched Analysis of Bi-National Colorectal Cancer Audit Data

BACKGROUND

Minimally invasive surgery is commonly used in the treatment of rectal cancer, despite the lack of evidence to support oncological equivalence or improved recovery compared with open surgery.

OBJECTIVE

This study aims to analyze prospectively collected data from a large Australasian colorectal cancer database.

DESIGN

This is a retrospective cohort study using propensity score matching.

SETTING

This study was conducted using data supplied by the Bi-National Colorectal Cancer Audit.

PATIENTS

A total of 3451 patients who underwent open (n = 1980), laparoscopic (n = 1269), robotic (n = 117), and transanal total mesorectal excision (n = 85) for rectal cancer were included in this study.

MAIN OUTCOME MEASURE

The primary outcome was positive margin rates (circumferential resection margin and/or distal resection margin) in patients treated with curative intent.

RESULTS

Propensity score matching yielded 1132 patients in each of the open and minimally invasive surgery groups. Margin positivity rates and lymph node yields did not differ between groups. The open group had a significantly lower total complication rate (27.6% vs 35.8%, p < 0.0001), including a lower rate of postoperative small-bowel obstruction (1.2% vs 2.5%, p = 0.03). The minimally invasive surgery group had significantly lower wound infection rate (2.9% vs 5.0%, p = 0.02) and a shorter length of hospital stay (8 vs 9 days, p < 0.0001). There was no difference in 30-day mortality.

LIMITATIONS

Results are limited by the quality of registry data entries.

CONCLUSION

In this patient population, minimally invasive proctectomy demonstrated similar margin rates in comparison with open proctectomy, with a reduced length of stay but a higher overall complication rate. See Video Abstract at http://links.lww.com/DCR/B190. RESULTADOS DE LA PROCTECTOMÍA MÍNIMA INVASIVA VERSUS ABIERTA PARA EL CÁNCER DE RECTO: UN ANÁLISIS DE PROPENSIÓN DE LOS DATOS BINACIONALES DE AUDITORÍA DEL CÁNCER COLORRECTAL: La cirugía mínima invasiva, frecuentemente se utiliza en el tratamiento del cáncer rectal, a pesar de la falta de evidencia que respalde la equivalencia oncológica o la mejor recuperación, en comparación con la cirugía abierta.El estudio tiene como objetivo analizar datos prospectivamente obtenidos, de una gran base de datos de cáncer colorrectal de Australia.Estudio de cohorte retrospectivo utilizando el emparejamiento de puntaje de propensión.Este estudio se realizó utilizando datos proporcionados por la Auditoría Binacional del Cáncer Colorrectal.Se incluyeron en este estudio un total de 3451 pacientes que se trataron de manera abierta (n = 1980), laparoscópica (n = 1269), robótica (n = 117) y taTME (n = 85) para cáncer rectal.Los resultados primarios fueron de tasas de margen positivas (margen de resección circunferencial y/o margen de resección distal) en pacientes con intención curativa.La coincidencia de puntaje de propensión arrojó 1132 pacientes en cada uno de los grupos de cirugía abierta y mínima invasiva. Las tasas de positividad del margen y los rendimientos de los ganglios linfáticos no difirieron entre los dos grupos. El grupo abierto tuvo una tasa de complicaciones totales significativamente menor (27.6% vs 35.8%, p <0.0001), incluida una tasa menor de obstrucción postoperatoria del intestino delgado (1.2% vs 2.5%, p = 0.03). El grupo de cirugía mínimamente invasiva tuvo una tasa de infección de la herida significativamente menor (2.9% frente a 5.0%, p = 0,02) y una estancia hospitalaria más corta (8 frente a 9 días, p <0.0001). No hubo diferencias en la mortalidad a los 30 días.Los resultados están limitados por la calidad de la entrada de datos de registro.En esta población de pacientes, la proctectomía mínima invasiva demostró tasas de margen similares en comparación con la proctectomía abierta, con una estadía reducida pero una tasa más alta de complicaciones en general. Consulte Video Resumen en http://links.lww.com/DCR/B190. (Traducción-Dr. Fidel Ruiz Healy).

Robotic surgery for colorectal disease: review of current port placement and future perspectives

Purpose

As robotic surgery is increasingly performed in patients with colorectal diseases, understanding proper port placement for robotic colorectal surgery is necessary. This review summarizes current port placement during robotic surgery for colorectal diseases and provides future perspective on port placements.

Methods

PubMed were searched from January 2009 to December 2018 using a combination of the search terms “robotic” [MeSH], “colon” [MeSH], “rectum” [MeSH], “colorectal” [MeSH], and “colorectal surgery” [MeSH]. Studies related to port placement were identified and included in the current study if they used the da Vinci S, Si, or Xi robotic system and if they described port placement.

Results

This review included 77 studies including a total of 3,145 operations. Fifty studies described port placement for left-sided and mesorectal excision; 17, 3, and 7 studies assessed port placement for right-sided colectomy, rectopexy, transanal surgery, respectively; and one study assessed surgery with reduced port placement. Recent literatures show that the single-docking technique included mobilization of the second and third robotic arms for the different parts without movement of patient cart and similar to previous dual or triple-docking technique. Besides, use of the da Vinci Xi system allowed a more simplified port configuration.

Conclusion

Robot-assisted colorectal surgery can be efficiently achieved with successful port placement without movement of patient cart dependent on the type of surgery and the robotic system.

Security and Radical Assessment in Open, Laparoscopic, Robotic Colorectal Cancer Surgery: A Comparative Study

Purpose:

This retrospective study was designed to assess the safety and effectiveness of open, laparoscopic, robotic colorectal cancer surgery.

Methods:

Three hundred patients with colorectal cancer who underwent curative resection in the First Affiliated Hospital of Zhengzhou University between February 2014 and May 2016 were included. Patients were classified into open surgery group, laparoscopic surgery group, and robot-assisted group.

Results:

The blood loss in laparoscopic surgery group was less than that in open surgery group, and the blood loss in robot-assisted group less was than the open surgery group. The number of lymph node dissection in robot-assisted group was significantly larger than that in the open group (P < .05). The distance between the lower edge of the tumor group and the distal margin in robotic group was longer than that of the laparoscopic surgery group and the open group (P < .05). Three (2.8%) cases of urinary retention occurred in the open surgery group, 4 (3.92%) cases in the laparoscopic surgery group, and 1 (1.1%) case in the robot-assisted group, while 2 (1.87%) cases of sexual dysfunction occurred in the open surgery group, 2 (1.96%) cases in the laparoscopic surgery group, and 1 (1.1%) case in the robot-assisted group. The urinary retention and sexual dysfunction rate did not differ between the 3 groups (P > .05), but the minimally invasive group showed a certain advantage over the open group.

Conclusion:

Compared to the traditional open surgery, minimally invasive surgery (especially in robot-assisted group) has advantages such as less intraoperative bleeding, rapid postoperative recovery, and radical cure; open group, laparoscopic surgery group, and robot-assisted group have a similar incidence of postoperative complications, but reduction in the incidence of anastomotic leakage and intestinal obstruction. Robot-assisted group has the potential advantage for pelvic autonomic nerve protection.