Clinical Efficacy and Pathological Outcomes of Transanal Endoscopic Intersphincteric Resection for Low Rectal Cancer

doi:10.21203/rs.3.rs-3241936/v1

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Research Article

Clinical Efficacy and Pathological Outcomes of Transanal Endoscopic Intersphincteric Resection for Low Rectal Cancer

https://doi.org/10.21203/rs.3.rs-3241936/v1

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Purpose

Transanal endoscopic intersphincteric resection (ISR) surgery currently lacks sufficient clinical research and reporting. In this study, we present the surgical outcomes, perioperative complications, and pathological findings based on the transanal endoscopic ISR surgeries performed in our center, aiming to contribute to the clinical application and development of this technique.

Methods

This study utilized a retrospective case series study design. Clinical and pathological data of patients with low rectal cancer who underwent transanal endoscopic ISR at the First Affiliated Hospital of Xiamen University from May 2018 to May 2023 were collected. All patients underwent transanal endoscopic ISR as the surgical approach. We conducted a study to report on the perioperative recovery status, postoperative complications, and pathological specimen characteristics of this group of patients.

Results

This study included a total of 45 eligible cases, with no perioperative deaths. The overall incidence of early complications was 22.22%, with a rate of 4.44% for Clavien-Dindo ≥ III. Two patients (4.4%) developed anastomotic leakage after surgery, including one case of grade A and one case of grade B. Postoperative pathological examination confirmed negative circumferential resection margin (CRM) and distal resection margin (DRM) in all patients. The distance between the tumor lower margin and DRM was found to be 2.30 ± 0.62 cm. Transanal endoscopic ISR surgery consistently yields excellent quality pathological specimens.

Conclusions

Transanal endoscopic ISR is safe and feasible, providing a clear anatomical view. It is associated with a low incidence of postoperative complications and achieves favorable pathological outcomes, making it worthy of further research and application.

Intersphincteric resection

Transanal

Rectal cancer

Complications

Endoscopic

As an advanced technique for ultra-low rectal cancer with the aim of sphincter preservation, intersphincteric resection (ISR) has been widely used in clinical practice. ISR surgery involves the removal of part or all of the internal sphincter while preserving the external sphincter, enabling patients to retain voluntary bowel function and significantly improving their postoperative quality of life compared to Abdominoperineal Resection (APR). Additionally, ISR ensures oncological safety[1, 2]. Studies have shown that most patients achieve satisfactory anal continence after surgery. In 1994, Schiessel et al. proposed the technique of ISR for ultra-low rectal cancer, pushing the boundaries of sphincter preservation surgery and gradually gaining widespread recognition[3]. In 2003, Rullier et al. first reported laparoscopic ISR[4], and in 2017, Kiyasu et al. reported a case of transanal endoscopic ISR for treating rectal cancer in a patient with coexisting prostatic hyperplasia, demonstrating the safety and feasibility of transanal endoscopic ISR[5]. Currently, the transabdominal approach for ISR remains the most commonly utilized surgical method in current clinical practice, with fewer reports on transanal endoscopic ISR. However, transanal endoscopic ISR offers unique anatomical advantages, particularly in terms of distal tumor margin and neural function preservation.

In recent years, our center has conducted extensive research and accumulated experience in transanal endoscopic ISR procedures. In this study, we present the surgical outcomes, perioperative complications, and pathological findings based on the transanal endoscopic ISR surgeries performed in our center, aiming to contribute to the clinical application and development of this technique.

Study design

Inclusion criteria: (1) Biopsy-proven rectal adenocarcinoma patients who underwent transanal endoscopic ISR. (2) Tumor height of 2–5 cm from the anal verge based on magnetic resonance imaging (MRI) and intraoperative measurement. (3) Tumors that did not involve the external anal sphincter, as confirmed by MRI. Exclusion criteria: (1) Patients with missing surgical and pathological data. (2) Preoperative imaging examinations revealing distant metastases. (3) Patients with bleeding or bowel obstruction perforation requiring emergency surgery. (4) Preoperative anal sphincter dysfunction. The study was approved by the Ethics Committee at the First Affiliated Hospital of Xiamen University.

Endpoints

The primary endpoints included postoperative complication occurrence and pathological specimen characteristics. The secondary endpoint was perioperative recovery status.

Complications are classified according to the Clavien-Dindo (CD) classification system[6]. The diagnosis and severity grading of anastomotic leakage will follow the 2010 criteria established by the International Study Group of Rectal Cancer (ISREC)[7].

Surgery procedure

All surgeries were performed by two surgical groups simultaneously, a group starting from the abdominal direction and a group starting from the anal direction. The primary surgeons for all cases had extensive experience in rectal cancer curative surgeries, performing over 200 cases of rectal cancer curative surgery each year. The surgeries were classified into partial ISR, subtotal ISR, or total ISR based on the distance between the tumor margin and the anal verge[3, 8]. For cases where the distance between the tumor lower edge and the dentate line was ≥ 2cm, partial ISR was performed, while for cases with a distance of 1-2cm, subtotal ISR was performed. Total ISR was performed when the tumor was located within 1cm of the dentate line. Figure 1A and 1B illustrate the surgical resection range.

The abdominal portion is performed under laparoscopic guidance, involving the preservation of the left colic artery and D3 lymph node dissection. A routine clearance of 253 lymph node groups is performed. The dissection extends anteriorly to the level of the seminal vesicles and posteriorly to the level of the sacral fascia.

In the transanal portion, the single-port laparoscopic platform used in this study was the STAR-PORT soft single-port laparoscopic platform produced by Xiamen SAIKEDA Medical Equipment company. The insufflator used in this study was the AirSeal™ constant pressure insufflator (ConMed, 525 French Road, Utica, New York, USA), typically providing a carbon dioxide insufflation pressure of 8–10 mmHg through the anal cavity. The energy devices used in this study were mainly electrocautery hooks. Low-energy electrocautery hooks were commonly used for incising the intestinal wall and muscle tissue to identify the intersphincteric space (ISS). In cases where the anatomical plane was unclear, an ultrasonic scalpel was promptly employed to separate and locate the correct surgical plane. The appropriate choice of energy devices contributed to achieving more precise dissection. The patient's position and surgical instruments are shown in Figs. 2A, 2B, and 2C.

The intraoperative illustrations are shown in Fig. 3A-3I. The LoneStar retractor was used to open the anus, and the distal rectum was sterilized. For patients undergoing modified ISR, a circular incision was made in the rectal wall or anal mucosa, with the incision line located 2 cm away from the tumor on the tumor side. The incision line was arc-shaped towards the tumor's opposite side, with a lateral margin of about 1 cm, while preserving the normal inner sphincter and dentate line on the tumor's opposite side. Under direct vision, the anal canal, inner sphincter, and combined longitudinal muscle were incised to expose the ISS. To ensure the safety of the circumferential resection margin (CRM), the surgical principle was to free the outer side of the ISS, while removing the inner sphincter and combined longitudinal muscle. At 1 cm from the tumor's distal end, the bowel lumen was closed using purse-string sutures to avoid the risk of tumor cell shedding during the operation and to ensure the principles of aseptic and tumor-free surgery.

After achieving a sufficient exposure, the STAR-PORT was inserted into the ISS, and a CO² pneumoperitoneum was established. The ISS was dissected in the sequence of "posterior, lateral, and anterior." First, the posterior ISS was opened, and part of the hiatal ligament and anococcygeal ligament's ventral layer were exposed. Continue to separate the remaining posterior hiatal ligament towards the 3 o'clock to 9 o'clock positions, and then cut the hiatal ligament to access the superior space of the levator ani. After clear exposure of the anococcygeal ligament, cut the ventral side of the anal coccygeal ligament close to the anterior rectal wall, completing the dissection of the posterior half of the ISS. During the dissection of the anterior ISS, the rectourethral muscle was cut close to the anterior rectal wall to reduce damage to the cavernous nerves in the rectourethral muscle and preserve urinary and reproductive functions. At the same time, care was taken to protect the neurovascular bundles (NVB) at the 2 o'clock and 10 o'clock positions and the pelvic plexus nerves in the rectal lateral space. After cutting the rectourethral muscle, the dissection should be conducted close to the posterior aspect of the prolapsed organ, and the surgical view should be gradually lowered until meeting with the abdominal group, to avoid damaging organs such as the prostate. For female patients, the surgeon could use their fingers to enter the vagina and guide the separation between the rectum and the posterior vaginal wall, reducing the risk of damaging the posterior vaginal wall.

Digestive tract reconstruction can be performed using hand-sewn anastomosis or stapler anastomosis. For patients undergoing hand-sewn anastomosis, the colon wall was fully sutured to the corresponding site of the rectum at the 3, 6, 9, and 12 o'clock positions with 4 full-thickness sutures. Then, the pre-placed 4 sutures were threaded from the outside to the inside and fully sutured to the corresponding site of the colon tube, followed by necessary reinforcement to complete digestive tract reconstruction. Patients were diverted with a loop ileostomy. Placement of a drainage tube in the pelvic cavity is a routine procedure. All surgical procedures adhere to the basic principles outlined in relevant clinical guidelines[9].

EAS: External anal sphincter

IAS: Internal anal sphincter

LAM: Levator ani muscle

ISS: Intersphincteric space

LL: Conjoint longitudinal muscle layer

ACL: Anococcygeal ligament

MR: Mesorectum

RUM: Rectourethralis muscle

SV: Seminal vesicle

Follow-up

After surgery, all patients undergo regular follow-up, which includes methods such as telephone consultations, outpatient visits, and inpatient examinations. Patients are followed up regularly every 3 months in the first 2 years and every 6 months thereafter. The follow-up examinations mainly include laboratory blood tests, computed tomography scans, and physical examinations. Endoscopy is recommended once a year after the operation.

Statistical analysis

Normally distributed continuous data are presented as mean ± standard deviation (SD), while skewed distributed continuous data are presented as median (range). Categorical data are presented as frequencies and percentages. Data analysis was performed using SPSS 26.0 statistical software.

Patient characteristics

Table 1 shows the demographics and clinical characteristics. According to the inclusion and exclusion criteria, a total of 45 patients who underwent transanal endoscopic ISR between May 2018 to May 2023 were included in this study (Fig. 4). The median distance between the tumors and the anal verges was 3.87 cm (range, 2.30–5.00 cm). Twelve patients (26.67%) had received neoadjuvant chemoradiotherapy. All patients underwent transanal endoscopic ISR surgery successfully according to the preoperative plan, and there were no perioperative deaths.

Table 1

Preoperative characteristic of 45 patients with rectal cancer who underwent transanal endoscopic ISR
Characteristic	Data
Gender, n (%)
Female	16 (35.56%)
Male	29 (64.44%)
Age, mean ± SD (year)	57.91 ± 12.571
BMI, mean ± SD (kg/m²)	23.39 ± 3.41
Weight, mean ± SD (kg)	64.13 ± 11.40
Hight, mean ± SD (cm)	163.93 ± 6.93
Hypertension, n (%)	9 (20.00%)
Diabetic, n (%)	6 (13.33%)
ASA grading, n (%)
I	4 (8.89%)
II	33 (73.33%)
III	8 (17.78%)
Neoadjuvant chemoradiotherapy, n (%)
No	33 (73.33%)
Yes	12 (26.67%)
Height from anal verge, M (range) (cm)	3.87 (2.50-5.00)
BMI: Body mass index ASA: American society of anesthesiologists

Perioperative results

It took a median of 221.22 min (range,120–345 min) to complete the whole procedure. Median intraoperative blood loss was 49.11 mL (range, 20–300 mL), median postoperative hospital stay was 10.29 days (range, 5–24 days), median time to resumption of oral intake was 5.47 days (range, 2–18 days), median duration of gastric tube placement was 1.18 days (range, 0–3 days), and median duration of abdominal drainage tube placement was 8.76 days (range, 4–21 days). Refer to Table 2.

In this group of patients, 10 patients (22.2%) experienced postoperative complications, including 8 patients (17.78%) of CD grade I-II and 2 patients (4.44%) of CD grade III-IV. There were no cases of CD grade V. Two patients (4.4%) developed anastomotic leakage after the surgery, which were successfully treated with abdominal drainage, irrigation, or antibiotic therapy. Three patients (6.67%) developed postoperative intestinal obstruction, 1 patient (2.22%) experienced urinary retention, 1 patient (2.22%) developed pelvic abscess, 6 patients (13.33%) had lung infection, and 1 patient (2.22%) had pleural effusion. All complications were successfully managed with appropriate treatment. There were no readmissions or perioperative deaths within 30 days.

Table 2

Perioperative results of 45 patients with rectal cancer who underwent transanal endoscopic ISR
Characteristic	Data
Operative time, M (range) (min)	221.22 (120–345)
Intraoperative blood loss, M (range) (ml)	49.11 (20–300)
Anastomotic technique, n (%)
Stapled	19 (42.22%)
Manual	26 (57.78%)
Ileostomy or colostomy, n (%)
Yes	45 (100%)
No	0
Postoperative hospital stay, M (range) (d)	10.29 (5–24)
Time to first soft diet, M (range) (d)	5.47 (2–18)
Removal of abdominal drainage, M (range) (d)	8.76 (4–21)
Removal of gastric tube, M (range) (d)	1.18 (0–3)
Overall postoperative complications	10 (22.22%)
Anastomotic leakage, n (%)
Grade A	1 (2.22%)
Grade B	1 (2.22%)
Grade C	0
Intestinal obstruction	3 (6.67%)
Urinary retention	1 (2.22%)
Pelvic abscess	1 (2.22%)
Pulmonary infection	6 (13.33%)
Pleural effusion	1 (2.22%)
Clavien–Dindo classifification
Dindo I–II	8 (17.78%)
Dindo III–IV	2 (4.44%)
Dindo V	0
Readmission within 30 days, n (%)	0
Death within 30 days, n (%)	0

Pathological results

As shown in Table 3, among the 45 included patients, postoperative pathological examination revealed negative CRM and distal resection margin (DRM) in all patients. The distance between the tumor lower margin and DRM was found to be 2.30 ± 0.62 cm. The mean diameter of the tumors was 2.86 cm (range, 0.80–4.60 cm), with a median of 19.56 (range, 8–40) lymph nodes retrieved and a median of 0.91 (range, 0–7.0) positive lymph nodes. According to the AJCC staging system, the postoperative pathological TNM stages were as follows: stage I in 24 cases (53.33%), stage II in 7 cases (15.56%), and stage III in 14 cases (31.11%).

Table 3

Pathologic results of 45 patients with rectal cancer who underwent transanal endoscopic ISR
Characteristic	Data
Pathological T stage, n (%)
T1	3 (6.67%)
T2	32 (71.11%)
T3	10 (22.22%)
Pathological N stage, n (%)
N0	31 (68.89%)
N1	10 (22.22%)
N2	4 (8.89%)
Pathological TNM stage, n (%)
I	24 (53.33%)
II	7 (15.56%)
III	14 (31.11%)
Tumor size, M (range) (cm)	2.86 (0.80–4.60)
Number of lymph nodes harvested, M (range)	19.56 (8–40)
Number of positive lymph nodes, M (range)	0.91 (0–7.0)
Length between tumor and DRM, mean ± SD (cm)	2.30 ± 0.62
CRM status, n (%)
Positive	0
Negative	45 (100%)
DRM status, n (%)
Positive	0
Negative	45 (100%)
CRM: circumferential resection margin DRM: distal resection margin TNM: Tumor-node-metastasis Tumors were classifed according to the American Joint Committee on Cancer (AJCC) TNM system

Our Research Findings

Transanal endoscopic ISR as an emerging technique for the treatment of ultra-low rectal cancer has gradually been adopted in clinical practice in recent years. With the magnified view provided by the endoscope, transanal endoscopic ISR allows for tumor excision through the anal canal approach, offering significant advantages over transabdominal ISR in terms of determining the distal margin and preserving the neurovascular bundle surrounding the rectum.

As an established technique for sphincter preservation in the treatment of ultra-low rectal cancer, ISR has shown promising results in various studies. Research indicates that achieving a 1 cm DRM and a 1 mm CRM in ISR can lead to a 5-year disease-free survival (DFS) rate of 80.2% and a local recurrence (LR) rate of 5.8%[10]. For experienced surgical teams, oncological outcomes are completely safe and assured. In a comparative study by Koyama et al. between APR and transabdominal ISR[11], the LR rate in the APR group of 33 patients was 12.1%, while the ISR group of 77 patients had a lower LR rate of 7.8%. Moreover, the 5-year overall survival (OS) rate for the APR group was 51.2%, which was lower than the 76.4% rate for the ISR group. In another large-scale study on survival prognosis in low rectal cancer, the 3-year cumulative LR rate was 3.9% for the APR group and 7.3% for the ISR group, while the 5-year OS rate was 67.9% for the APR group and 69.9% for the ISR group[2]. Similarly, in a retrospective comparative study conducted by Kim, which included a total of 624 patients with rectal cancer undergoing low anterior resection (LAR) and ISR, the results showed no statistically significant differences in the 5-year OS, DFS, and LR between the LAR group and ISR group[12]. In a comparative study by Kang et al. on transanal total mesorectal excision (TaTME) combined with ISR versus APR[13], the 3-year DFS was 86.3% in the TaTME combined with ISR group and 75.1% in the ISR group. The 3-year OS was 96.7% in the TaTME combined with ISR group and 94.2% in the APR group, with no statistically significant differences between the two surgical approaches in terms of 3-year DFS and OS for the patients. The above-mentioned studies collectively suggest that both traditional transabdominal ISR and transanal endoscopic ISR achieve comparable oncological outcomes to APR and even show potential for better survival prognosis in some studies. From an oncological safety perspective, both approaches are completely feasible.

The average postoperative hospital stay for patients in this group was 10.29 (5–24) days, with most patients having their gastric tubes removed on the second day after surgery. Our study found an overall postoperative complication rate of 22.22%, and the incidence of major complications (CD ≥ 3) was low (4.44%). Pulmonary infections being the most common complication, possibly related to the older age of the patients. Previous studies have consistently shown that the incidence of postoperative complications after ISR ranges from 17.2–25.8%[14, 15], which is consistent with the findings of our study. Three cases of intestinal obstruction occurred during the perioperative period, and early mobilization of patients and avoiding prolonged bed rest could further reduce the occurrence rate. Considering multiple research results, the incidence of anastomotic leakage after surgery for low rectal cancer is mostly between 5.3% and 13.9%[16–18]. In our study, only two patients experienced anastomotic leakage, with an incidence rate of 4.44%, significantly lower than the aforementioned results. We believe this is related to the excellent preservation of vascular and neural bundles achieved through the transanal endoscopic approach, which reduces the risk of ischemia in the vicinity of the anastomosis.

One patient experienced urinary retention, and reviewing the surgical video, we found that it might be related to intraoperative damage to the genitourinary nerves. The patient was treated with catheterization and appropriate bladder function exercises, resulting in a good recovery. However, it is worth noting that in our study, the incidence rate of perioperative urinary retention was only 2.22%. Based on the comparison with several previous studies on transabdominal approach surgeries, we found that the incidence of urinary dysfunction during the perioperative period was mostly between 3.1% and 41.0%[19–21], significantly higher than that observed in our transanal endoscopic ISR study. This notable difference can be attributed to the favorable exposure and preservation of the genitourinary nerves achieved through the transanal endoscopic approach during the dissection, as opposed to the traditional transabdominal approach. Therefore, we can observe the significant advantages of transanal endoscopic ISR in preserving patients' genitourinary function.

Tumor radical resection is a crucial factor determining surgical outcomes; otherwise, it may significantly impact patients' postoperative survival and risk of recurrence. The DRM, CRM, and number of lymph nodes removed are all essential indicators of the achieved surgical radicality. In this study, all patients had negative DRM and CRM, with the tumor DRM distance being 2.30 ± 0.62 cm, indicating high-quality surgical specimens. One significant advantage of the transanal endoscopic approach for ISR is that it can precisely ensure a safe distance of the DRM while achieving optimal sphincter preservation. Generally, during the surgery, we usually perform purse-string sutures 1 cm away from the tumor distal end under direct vision. This step not only seals the tumor distal end to avoid potential tumor cell shedding risk but also ensures that all patients have a DRM of more than 1 cm. After closing the distal end of the rectum, we typically make a circular incision 1 cm away from the purse-string suture to determine the resection line. Therefore, in most cases, most patients can ensure a DRM of 2 cm or more. For patients who cannot achieve a 2 cm DRM, we usually perform an intraoperative tissue rapid frozen pathology examination to ensure an unequivocally negative DRM.

In recent years, studies have found that rectal cancer rarely infiltrates the distal margin. Research has confirmed that there is no statistically significant difference in LR and OS between a 2 cm DRM and a 5 cm DRM[22, 23]. Therefore, a 2 cm DRM is also widely accepted as the margin distance by many surgeons. Further research has revealed that in the majority of low rectal cancers, tumor cells infiltrate the distal margin to a distance less than 1 cm. In a meta-analysis involving 5,574 patients, it was found that there was no statistically significant difference in LR and OS between a DRM ༞1 cm and a DRM ༜1 cm[24]. Another study on prognostic factors after ISR found that a DRM ༜1 cm was not an independent risk factor for patients' postoperative local recurrence(LR) and OS[25]. For extremely precious distal rectum segments close to the dentate line, we believe that a DRM ༞1 cm is sufficient to ensure oncological safety.

In a meta-analysis by Martin et al. that included 14 studies comprising a total of 1289 cases of rectal cancer ISR[15], the overall negative rate of CRM was 96.0%, and the R0 resection rate was 97%. This study also demonstrated that the status of CRM independently influenced the survival prognosis of ISR patients. In contrast, our research demonstrates that transanal endoscopic ISR results in excellent quality of pathological specimens. We believe that this is mainly due to the unique advantage of transanal endoscopy in distinguishing the rectal-anal structures during the surgical pathway. Additionally, the total number of lymph nodes removed during the surgery in this group was 19.56 (8–40). Because the abdominal portion of the procedure is consistent with the traditional laparoscopic approach for ISR, the lymph node retrieval is comparable to the traditional transabdominal approach[26, 27].

Surgical Skills and Experiences

There is a physiological curvature in the anatomy of the rectum, which makes it challenging to achieve precise localization of the DRM during ISR through an transabdominal approach[28, 29]. Moreover, for patients with pelvic narrowing, the separation of the ISS can be even more challenging. In the traditional laparoscopic ISR procedure, the transanal portion requires direct visualization for the separation of the distal rectum and ISS. However, the clarity of the visual field is still not as good as with transanal endoscopy. In our center, we applied the transanal endoscopic ISR technique for the treatment of ultralow rectal cancer. With the high-definition magnification provided by the transanal endoscope and the expansion of the port, the visual field can be better exposed, making the separation of the ISS simpler, more accurate, and facilitating precise localization of the distal resection margin. Under the transanal endoscopic view, both the radial fibers of the combined longitudinal muscle and the internal anal sphincter can be clearly displayed. The use of an electric cautery allows for the distinct identification of the contracting red external anal sphincter and the non-contracting white internal anal sphincter.

Our experience is generally to start by freeing the posterior ISS, then proceed to free the space on both sides, and finally move to the anterior ISS. When freeing the posterior and lateral ISS, as we enter the space above the levator ani muscle, we closely adhere to the rectal posterior wall and cut the abdominal layer of the anococcygeal ligament. The Hiatal ligament forms a U-shaped closure of the puborectal hiatus, and it has a firm texture, while the tissues at the 5 o'clock and 7 o'clock positions of the lithotomy position are relatively weak. We believe that the optimal approach is to first open the posterior ISS and dissect towards the head side to expose a portion of the Hiatal ligament and the anterior aspect of the anorectal ligament. Then, in a U-shaped manner, we continue separating the remaining posterior Hiatal ligament, with the separation extending approximately from the 3 o'clock to 9 o'clock positions of the lithotomy position, allowing access to the puborectal hiatus in this area by cutting the Hiatal ligament. After the posterior Hiatal ligament is cut, we proceed to closely dissect the rectal posterior wall to cut the abdominal layer of the anococcygeal ligament.

When separating the anterior ISS, our experience involves using a low-energy setting on the electric cautery, which effectively reduces bleeding and nerve damage. There is generally a weak area in the levator ani muscle, regardless of whether in males or females. In males, this weak area is usually located between the 11 and 1 o'clock positions, and in females, it is between the 10 and 2 o'clock positions[30]. During the dissection of the anterior ISS, this weak point can be used as a starting point to locate the rectourethral muscle, which is situated behind the external sphincter ring. After dividing the fibers of the rectourethral muscle, the Denonvilliers' fascia can be reached, and the urethra in males or the posterior wall of the vagina in females can be exposed, entering the pre-rectal space. During the dissection of the anterior ISS, it is necessary to approach the rectal anterior wall to divide the rectourethral muscle and minimize damage to the cavernous nerves, thereby preserving the patient's urinary and reproductive functions. Careful identification and protection of the neurovascular bundle (NVB) at the 2 o'clock and 10 o'clock positions, as well as the pelvic plexus nerves within the lateral rectal space, are essential. These nerves play a critical role in preserving postoperative sexual function for the patients[31–33]. By paying close attention to identification and employing gentle techniques, it is possible to minimize damage to these crucial nerve structures, thereby maximizing the preservation of postoperative sexual function for the patients. Preserving sexual and urinary function for patients with low rectal cancer is one of the challenging aspects of the surgery[34]. However, utilizing the visual and angle advantages of transanal endoscopy allows for excellent protection of the aforementioned sexual and urinary-related organs and nerves. This is of significant importance in safeguarding pelvic autonomic nerve function.

Throughout the entire surgical procedure, the surgeon should strictly adhere to the principles of total mesorectal excision and consistently emphasize the awareness of meticulous vascular and nerve dissection and protection. Only in this way can the advantages of the transanal endoscopic approach for ISR be fully maximized.

In summary, this study provides a report on the transanal endoscopic ISR surgeries performed at our center in recent years. The study found that transanal endoscopic ISR offers excellent surgical visualization and facilitates the protection of the perirectal vasculature and nerves. The procedure has minimal postoperative complications, yields high-quality pathological specimens, and demonstrates excellent oncological outcomes. This research holds valuable implications for the widespread implementation of the transanal endoscopic ISR technique. However, further investigations with larger sample sizes are still warranted.

Ethics approval and consent to participate

This study has been approved by the Ethics Committee at the First Affiliated Hospital of Xiamen University. Patient consent was waived due to the retrospective character of the study, and it was approved by the Ethics Committee at the First Affiliated Hospital of Xiamen University. All procedures performed in studies involving human participants were conducted according to the ethical standards of the institutional research committee and the Helsinki declaration and later revision.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Funding

This research is supported by the Natural Science Foundation of Fujian Province (2021J011360) and Medical Innovation Project of Fujian Provincial Health Commission (2021CXB019).

Authors' Contributions

Study conception and design: Jun You, Qingqi Hong. Formal analysis and Writing original draft: Zhiwen Xu. Manuscript editing: Jingtao Zhu, Haoyu Bai. All authors have read and approved the fnal manuscript.

Acknowledgments

The authors thank all of the people who contributed to this study.

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No competing interests reported.

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Clinical Efficacy and Pathological Outcomes of Transanal Endoscopic Intersphincteric Resection for Low Rectal Cancer

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