Intersphincteric Resection Research Articles

A comparative study on the short-term clinical outcomes of Da Vinci SP versus Da Vinci Xi for rectal cancer surgery.

The Da Vinci SP robot system was recently introduced, but its safety and feasibility for rectal cancer compared with the currently used robot system have not been reported. This was a single-centre retrospective study. Data from patients who underwent abdominal total mesorectal excision (TME) from October 2015 to October 2022 were analysed. After propensity score matching, the short-term outcomes were compared. A total of 56 patient data were analysed. Intersphincteric resection was more common in the SP group (7 cases (25%) vs. 0 case (0%), p=0.001). The operation time was significantly shorter in SP (184 vs. 227.5min, p<0.0001), but the docking time was similar. The postoperative complications were similar. There were no differences in the postoperative pain score and length of hospital stay. The SP robotic system for abdominal TME has acceptable short-term and is safe and technically feasible.

Endoscopic ultrasound-guided colo-colostomy for the treatment of benign complete occlusion of colonic anastomosis: a case series and description of technique.

The incidence of benign colonic anastomotic stricture is approximately 2% in patients undergoing left hemicolectomy or anterior resection and as high as 16% in patients undergoing low anterior or intersphincteric resection. In the majority, rather than complete occlusion, a stenosis forms, which can be managed with endoscopic balloon dilatation, a self-expanding metallic stent or endoscopic electroincision. In the less common scenario of a completely occluded colonic anastomosis, surgery is often required. In this study, we aim to describe the technique we used to treat this condition non-operatively METHOD: We describe a case series of three patients with benign complete occlusion of their colorectal anastomosis and how we managed them nonoperatively with a colonic/rectal endoscopic ultrasound (EUS) anastomosis technique and a Hot lumen-apposing metallic stent. We demonstrate that the technical and clinical success for this technique is 100%. We believe that the technique we describe is effective and safe. It should be widely reproducible in centres with expertise in interventional EUS, given the similarity to well-established procedures such as EUS-guided gastroenterostomy. Patient selection and timing of reversal of ileostomy need careful consideration, especially in patients with a history of keloid formation. Given the shorter hospital stay and reduced invasiveness of this technique, we believe it should be considered for all patients who have complete benign occlusion of a colonic anastomosis. However, given the small number of cases and short period of follow-up, the long-term outcome of this technique is not known. More studies with higher power and a longer period of follow-up should be conducted to further ascertain the effectiveness of this technique.

Risk factors, quality of life, and oncological effects of refractory anastomotic leakage for laparoscopic intersphincteric resection.

Refractory anastomotic leakage (RAL) after intersphincteric resection (ISR) usually leads to failure of protective stoma reversal in ultralow rectal cancers. The aim of this study is to assess the risk factors and oncological outcomes of both anastomotic leakage (AL) and RAL, and quality of life (QoL) of RAL after laparoscopic ISR (LsISR). A total of 371 ultralow rectal cancer patients with LsISR were enrolled from a tertiary colorectal surgery referral center. Risk factors for AL and RAL were identified by logistic regression. Three-year disease-free survival (DFS) of AL and RAL was analyzed by the Cox regression. QoL of RAL group (compared with non-RAL group) was assessed using the European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-CR29 questionnaires. The rates of AL and RAL after LsISR accounted for 8.4% (31/371) and 4.6% (17/371) in this cohort, respectively. Non-left colic artery preservation (odds ratio [OR]=3.491, P=0.009), neoadjuvant chemoradiotherapy (nCRT) (OR=6.038, P<0.001), and lower anastomosis height (OR=5.271, P=0.010) were independent risk factors for AL, while nCRT (OR=11.602, P<0.001) was the only independent risk factor for RAL. Male (hazard ratio [HR]=1.989, P=0.014), age>60years (HR=1.877, P=0.018), and lymph node metastasis (HR=2.125, P=0.005) were independent risk factors of poor 3-year DFS, but not RAL (P=0.646). RAL patients have significantly worse global health status, worse emotional and social function scores at the late postoperative stage, and worse urinary and sexual function at the early postoperative stage (all P<0.05). Neoadjuvant chemoradiotherapy was an independent risk factor for RAL after LsISR. RAL shows similar oncological outcomes, but with poor QoL.

Should anorectal manometry be routine before stoma reversal in patients after an intersphincteric resection?

Anorectal manometry (ARM) is sometimes performed before ostomy reversal in patients with an intersphincteric resection (ISR) to predict bowel function. However, no clinical predictive data exist regarding its utility. The single-centre, retrospective data of ISR patients who had an ARM prior to ostomy reversal, and bowel functional assessment with the low anterior resection syndrome (LARS) and Wexner incontinence scores at least 6 months after reversal, were considered. Correlation statistics were performed with each of the manometric parameters and functional outcome categories. Eighty-nine patients were included. The median basal and squeeze pressures were 41 and 100 mmHg, respectively. Any LARS (score ≥20) and major incontinence (score ≥11) was observed in 51.7% and 16.9%, respectively. None of the manometric parameters (median basal or maximum squeeze pressure, anal canal length, volume at urge and the ability to expel) correlated with LARS or incontinence. Anorectal manometry (ARM) before ostomy reversal to predict bowel function at 6 months or beyond was not helpful in patients with an ISR and diverting stoma. No manometric parameter correlated with the LARS or Wexner incontinence scores.

Long-term outcomes and failure patterns after laparoscopic intersphincteric resection in ultralow rectal cancers

Long-term outcomes and failure patterns after laparoscopic intersphincteric resection in ultralow rectal cancers

Clinical application and standardized implementation of intersphincteric resection

Intersphincteric resection (ISR) is the ultimate sphincter-preserving surgical technique for low rectal cancer. To promote the standardized implementation of ISR, this review discusses the important issues regarding the clinical application of ISR with reference to the latest Chinese expert consensus on ISR. In terms of ISR-related pelvic anatomy of the rectum/anal canal, hiatal ligament is not identical with the anococcygeal ligament. At the level where the rectourethralis muscle continuously extends to the posteroinferior area of the membranous urethra from the rectum, the neurovascular bundle is identified between the posterior edge of rectourethralis muscle and the anterior edge of the longitudinal muscle of the rectum. This knowledge is crucial to detect the anterior dissection plane during ISR at the levator hiatus level. The indication criteria for ISR included: (1) stage I early low rectal cancer; (2) stage II-III low rectal cancer undergoing neoadjuvant treatment, and supra-anal tumors and juxta-anal tumors of stage ycT3NxM0, or intra-anal tumors of stage ycT2NxM0. However, signet ring cell carcinoma, mucinous adenocarcinoma and undifferentiated carcinoma should be contraindicated to ISR. For locally advanced low rectal cancer (especially anteriorly located tumor), neoadjuvant treatment should be carried out in a standardized manner. However, it should be recognized that neoadjuvant chemoradiotherapy was a risk factor for poor anal function after ISR. For surgical approaches for ISR, including transanal, transabdominal, and transanal transabdominal approaches, the choice should be based on oncological safety and functional consequences. While ensuring the negative margin, maximal preservation of rectal walls and anal canal contributs to better postoperative anorectal function. Careful attention must be paid to complications regarding ISR, with special focus on the anastomotic complications. The incidence of low anterior resection syndrome (LARS) was higher than 40%. However, this issue is often neglected by clinicians. Thus, management and rehabilitation strategies for LARS with longer follow-ups were required.

Advances in functional assessment and bowel rehabilitation following intersphincteric resection for low rectal cancer

Intersphincteric resection (ISR) has been performed as an ultimate sphincter-sparing strategy in selected patients with low rectal cancer. Accumulating evidence suggests that ISR may be an interesting alternative to abdominoperineal resection to avoid a permanent stoma without compromising oncological outcomes. However, bowel dysfunction is a most common consequence of ISR not to be neglected. To date, limited clinical research has reported functional and quality of life outcomes according to patient-reported outcome measures. Also, data concerning management of low anterior resection syndrome are scarce due to lack of quality evidence. Therefore, this review provides an up-to-date summary of systematic assessment (including function, quality of life, manometry and morphology) and bowel rehabilitation for ISR patients. Postoperative anal function is often assessed by a combination of scales, including the Incontinence Assessment Scale, the Gastrointestinal Function Questionnaire, the Specific LARS Assessment Scale and the Faecal Diary. The condition-specific Quality of Life Scale is more appropriate for Quality-of-life measures in fecal incontinence after ISR. Patients' physiological function after ISR can be assessed using water- or high-resolution solid-state anorectal manometry. Anatomical and morphological changes can be assessed using defecography and 3D endorectal ultrasound. Electrical stimulation and biofeedback, pelvic floor exercises, rectal balloon training, transanal irrigation and sacral neuromodulation are all options for post-operative rehabilitation.

Chinese expert consensus on intersphincteric resection for low rectal cancer (2023 edition)

Intersphincteric resection (ISR) is the ultimate sphincter-preserving surgical technique for low rectal cancer. Accurate preoperative diagnosis and staging, appropriate selection of surgical approaches and technique, standardized perioperative management, and postoperative rehabilitation are the keys to ensuring the oncological effect and functional preservation of ISR. To date, there is still a lack of standardized guidance on the clinical implementation of ISR in China. Therefore, based on the latest evidence from literature, expert experience, and the intervention situation in China, the Chinese Society of Colorectal Surgery, Chinese Society of Surgery, Chinese Medical Association organized domestic experts in colorectal surgery to discuss and produce "Chinese expert consensus on intersphincteric resection for low rectal cancer (2023 edition)". This consensus focuses on definition, classification, related pelvic anatomy, operational techniques, postoperative complications, and long-term oncological and functional outcomes, and aims to guide the standardized clinical practice of ISR in the operation of low rectal cancer in China.

Anatomical and histological investigation of the area anterior to the anorectum passing through the levator hiatus

Objective: To document the anatomical structure of the area anterior to the anorectum passing through the levator hiatus between the levator ani slings bilaterally. Methods: Three male hemipelvises were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. (1) The anatomical assessment was performed in three ways; namely, by abdominal followed by perineal dissection, by examining serial cross-sections, and by examining median sagittal sections. (2) The series was stained with hematoxylin and eosin to enable identification of nerves, vessels, and smooth and striated muscles. Results: (1) It was found that the rectourethralis muscle is closest to the deep transverse perineal muscle where the longitudinal muscle of the rectum extends into the posteroinferior area of the membranous urethra. The communicating branches of the neurovascular bundle (NVB) were identified at the posterior edge of the rectourethralis muscle on both sides. The rectum was found to be fixed to the membranous urethra through the rectourethral muscle, contributing to the anorectal angle of the anterior rectal wall. (2) Serial cross-sections from the anal to the oral side were examined. At the level of the external anal sphincter, the longitudinal muscle of the rectum was found to extend caudally and divide into two muscle bundles on the oral side of the external anal sphincter. One of these muscle bundles angled dorsally and caudally, forming the conjoined longitudinal muscle, which was found to insert into the intersphincteric space (between the internal and external anal sphincters). The other muscle bundle angled ventrally and caudally, filling the gap between the external anal sphincter and the bulbocavernosus muscle, forming the perineal body. At the level of the superficial transverse perineal muscle, this small muscle bundle headed laterally and intertwined with the longitudinal muscle in the region of the perineal body. At the level of the rectourethralis and deep transverse perineal muscle, the external urethral sphincter was found to occupy an almost completely circular space along the membranous part of the urethra. The dorsal part of the external urethral sphincter was found to be thin at the point of attachment of the rectourethralis muscle, the ventral part of the longitudinal muscle of the rectum. We identified a venous plexus from the NVB located close to the oral and ventral side of the deep transverse perineal muscle. Many vascular branches from the NVB were found to be penetrating the longitudinal muscle and the ventral part of rectourethralis muscle at the level of the apex of the prostate. The rectourethral muscle was wrapped ventrally around the membranous urethra and apex of the prostate. The boundary between the longitudinal muscle and prostate gradually became more distinct, being located at the anterior end of the transabdominal dissection plane. (3) Histological examination showed that the dorsal part of the external urethral sphincter (striated muscle) is thin adjacent to the striated muscle fibers from the deep transverse perineal muscle and the NVB dorsally and close by. The rectourethral muscle was found to fill the space created by the internal anal sphincter, deep transverse perineal muscle, and both levator ani muscles. Many tortuous vessels and tiny nerve fibers from the NVB were identified penetrating the muscle fibers of the deep transverse perineal and rectourethral muscles. The structure of the superficial transverse perineal muscle was typical of striated muscle. These findings were reconstructed three-dimensionally. Conclusions: In intersphincteric resection or abdominoperineal resection for very low rectal cancer, the anterior dissection plane behind Denonvilliers' fascia disappears at the level of the apex of the prostate. The prostate and both NVBs should be used as landmarks during transanal dissection of the non-surgical plane. The rectourethralis muscle should be divided near the rectum side unless tumor involvement is suspected. The superficial and deep transverse perineal muscles, as well as their supplied vessels and nerve fibers from the NVB. In addition, the cutting direction should be adjusted according to the anorectal angle to minimize urethral injury.

Importance of comprehensive management of anastomotic site after ultra-low anal sphincter-preservation surgery

Intersphincteric resection (ISR) surgery increases the rate of anal sphincter preservation in patients with ultra-low rectal cancers. However, the anastomotic site of ISR surgery is at risk for structural healing complications such as anastomotic leakage, anastomotic dehiscence, secondary anastomotic stenosis, chronic presacral sinus, rectovaginal fistula, and rectourethral fistula, which can lead to a persistent defunctioning ostomy or a secondary permanent colostomy. This article systematically describes the preoperative high-risk factors and characteristics of anastomotic site structural healing complications after ISR surgery, as well as the management of the anastomotic site during various stages including hospitalization, from discharge to one month after surgery, from one month after surgery to before stoma reversal, and after stoma reversal. This is to provide a clearer understanding of the risks associated with the anastomotic site at different stages of the healing process and to timely detect and actively manage related complications, thereby reducing the rate of permanent colostomy and truly achieving the dual goals of "survival benefit" and "quality of life improvement" in ISR surgery.

Techniques and classification of intersphincteric resection for ultra-low rectal cancer

ISR is the most widely used anal-preserving operation for ultra-low rectal cancer. It can be divided into total ISR, subtotal ISR and partial ISR according to the resection range of internal sphincter. The advantage of ISR is that it can preserve the sphincter while ensuring the safety of oncology for ultra-low rectal cancer, representing the state of the art. However, it still needs to face the problem that the quality of life will decline due to poor postoperative anal function. The conformal sphincter-preserving operation (CSPO) is a functional anal-preserving surgery improved on the basis of ISR. It is superior to ISR in the postoperative anal function and patients' quality of life. So it can be a new choice for ultra-low rectal cancer.

Meta-analysis comparing long-term outcomes of intersphincteric resection versus abdominoperineal resection for low rectal cancer

Objective: To compare the long-term outcomes of intersphincteric (trans-internal and external) sphincter resection (ISR) and abdominoperineal proctocolectomy (APR) for low-grade rectal cancer. Methods: We used a meta-analytic approach to compare these procedures . Published reports comparing ISR and APR for low rectal cancer in Pubmed, Medline, EMBASE and Cochrane, China Knowledge Network (CNKI), China Biomedical Literature Database, and Vipers databases between January 2005 and January 2023 were searched and those meeting the eligibility criteria were selected for extraction of data for analysis. Inclusion criteria were as follows: (1) all reports comparing ISR and APR for low rectal cancer before January 2023; and (2) prospective randomized controlled studies or well-designed cohort studies. Exclusion criteria were as follows: (1) full text not available; (2) duplicate publications, missing primary outcome indicators, and unknown data; and (3) invalid statistical analysis. Results: Sixteen studies with 2498 patients were included in this study. Compared with the APR group, patients in the ISR group were relatively younger (weighted mean difference [WMD]=-1.82, 95%CI=-2.94 to -0.70, P=0.01), had tumors farther from the anal verge (WMD=0.43, 95%CI=0.18 to 0.67, P<0.01), and lower pathological T-stage (T3-4 stage: OR=0.54, 95%CI=0.36 to 0.81, P<0.01). In contrast, there were no statistically significant differences between the two groups in gender (P=0.78), body mass index (P=0.77), or pathological N stage (P=0.09). Compared with the APR group, patients in the ISR group had a lower rate of postoperative complications (OR=0.77, 95%CI=0.60 to 0.99, P=0.04), shorter hospital stay (WMD=-4.30, 95%CI=-7.07 to -1.53, P<0.01), higher 5-year overall survival (HR=0.54, 95%CI=0.33 to 0.88, P=0.01), and higher 5-year disease-free survival (HR=0.65, 95%CI=0.47 to 0.90, P<0.01). Five-year locoregional failure (HR=0.66, 95%CI=0.40 to 1.10, P=0.11) and time to surgery (WMD=-9.71, 95%CI=-41.89 to 22.47, P=0.55) did not differ significantly between the two groups. Conclusion: ISR is a safe and effective alternative to APR for early-stage low-grade rectal cancer.

Transanal total mesorectal excision versus laparoscopic intersphincteric resection for low rectal cancer: a propensity score matching analysis.

Anus-preserving surgery for low rectal cancer has always been a serious difficulty for surgeons. Transanal total mesorectal excision (TaTME) and laparoscopic intersphincteric resection (ISR) are commonly used Anus-preserving surgeries for low rectal cancer. The aim of this study was to compare the clinical use of two surgical methods. A total of 152 patients with low rectal cancer were treated with taTME in 75 cases and ISR in 77 cases. After propensity score matching, 46 patients in each group were included in the study. Perioperative outcomes, anal function scores (Wexner incontinence score) and quality of life scores (EORTC QLQ C30, EORTC QLQ CR38) at least 1year after surgery were compared between the two groups. There were no significant differences between the two groups in terms of surgical outcomes, pathological examination of surgical specimens, postoperative recovery, and postoperative complications, except for patients in the taTME group who had their indwelling catheters removed later. Anal Wexner incontinence score was lower in taTME group than ISR group (P < 0.05). On the EORTC QLQ-C30 scale, the physical function and role function scores in the ISR group were lower than those in the taTME group (P < 0.05), while the fatigue, pain symptoms, and constipation scores in the ISR group were higher than those in the taTME group (P < 0.05). On the EORTC QLQ-CR38 scale, the scores of gastrointestinal symptoms and defecation problems in the ISR group were higher than those in the taTME group (P < 0.05). Compared with ISR surgery, taTME surgery is comparable in terms of surgical safety and short-term efficacy, and has better long-term anal function and quality of life. From the perspective of long-term anal function and quality of life, taTME surgery is a better surgical method for the treatment of low rectal cancer.

How to reasonably deal with zero-events in meta-analysis of surgery-related outcomes? Oncologic outcomes of intersphincteric resection vs. abdominoperineal resection for lower rectal cancer: a systematic review and meta-analysis.

How to reasonably deal with zero-events in meta-analysis of surgery-related outcomes? Oncologic outcomes of intersphincteric resection vs. abdominoperineal resection for lower rectal cancer: a systematic review and meta-analysis.

Single-Port Robotic Intersphincteric Resection for the Treatment of Rectal Cancer.

The da Vinci Single-port (SP) system is designed to facilitate single-incision robotic surgery in a narrow space. We developed a new procedure of intersphincteric resection (ISR) using the SP platform and evaluated the technical safety and feasibility of this procedure for the treatment of very low rectal cancer. Eleven rectal cancer patients who underwent SP robotic ISR between August 2020 and July 2021 were included. Patients' clinical characteristics, operative and pathologic findings of the patients were retrospectively analyzed. The median tumor height was 3cm (range, 2-4cm). A single docking was performed, and the median docking time was 3min 10sec (range, 2min 50sec-3min 30sec). The median total operation time was 210min (range, 150-280min), and the median time of pelvic dissection was 57min (range, 45-68min). All patients presented with negative distal resection margins [median 1cm (range, 0.5-2.0cm)], and only one patient had less than 1mm of circumferential resection margin (0.9mm). Our initial experience suggests that SP robotic ISR is safe and feasible.

The role of image-guided volume-adapted high-dose-rate endorectal brachytherapy boost in total neoadjuvant treatment of distal locally advanced rectal cancer.

3611 Background: Endorectal brachytherapy has been used as palliative or preoperative treatment for advanced or locally advanced rectal cancer, with moderate radiation induced toxicity. This study aimed to explore the efficacy of high-dose-rate 192Ir brachytherapy combined with external beam radiotherapy (EBRT) in total neoajuvant treatment (TNT) of distal rectal cancer. Methods: From January 2017 to December 2022, eligible rectal adenocarcinoma patients were assessed as clinical stage II -III, with primary tumor located in distal rectum (≤5 cm from anal verge). The local staging was determined using endorectal ultrasound and magnetic resonance imaging (MRI). In addition, cases included in this study underwent preoperative semiweekly endorectal brachytherapy of 8-12Gy/2-3F/1-1.5w, followed by EBRT of 45-50.4Gy/25-28F, fluorouracil-based concurrent and consolidation chemotherapy. The brachytherapy was image-guided volume-adapted, and delivered by multi-channel 192Ir source applicators with different diameters. Radiation proctitis was graded from 0 to 4 using Radiation Therapy Oncology Group (RTOG) criteria. Results: A total of 40 cases were enrolled in this retrospective study, biopsy-proven and diagnosed as clinical stage II (n = 8), stage III (n = 32). The rates of T4 and positive circumferential resection margin (CRM) were 35% and 87.5% respectively. The median value of the interval from completion of radiotherapy to operation was 86 days (interquartile range: 75-98 days). After neoadjuvant treatment, 2 cases were undergoing the watch-and-wait strategy with sustained clinical complete response (cCR), 38 patients received operation and R0 resection rate was 97.4%. The pathological complete response (pCR) rate was 28.9%, and major pathological regression rate was 67.5%. The theoretical rate of anus preservation was 62.5%, including 6 of 21 cases underwent abdominoperineal resection but achieved pCR, 17 cases underwent low anterior resection or intersphincteric resection, and 2 cases with sustained cCR. After a median follow-up of 37 months (range 12-68 months), the 3-year disease-free survival, local-regional reccurence-free survival and overall survival was 81.1% (95%CI: 64.3%-91.2%), 94.9% (95%CI: 80.6%-98.5%) and 96.9% (95%CI: 82.1%-99.4%), respectively. No patients experienced Grade ≥3 radiation proctitis. The median Wexner fecal incontinence score of anus-preserving cases was 1 (range 0-8). Subgroup analysis showed that the complete response rate (pCR or sustained cCR) was lower in cases received 2 fractions brachytherapy than those received 3 fractions (27.8% vs 36.4%). Conclusions: The addition of image-guided volume-adapted high-dose-rate 192Ir endorectal brachytherapy boost to TNT could improve the pathological tumor response and anus preservation rate in distal locally advanced rectal cancer.

Comparison of anal function and quality of life after conformal sphincter preservation operation and intersphincteric resection of very low rectal cancer: a multicenter, retrospective, case–control analysis

PurposeConformal sphincter preservation operation (CSPO) is a sphincter preservation operation for very low rectal cancers. Compared to intersphincteric resection (ISR), CSPO retains more dentate line and distal rectal wall, and also avoids damaging the nerves in the intersphincteric space. This study aimed to compare the postoperative anal function and quality of life between the CSPO and ISR.MethodPatients with low rectal cancer undergoing CSPO (n = 117) and ISR (n = 66) were included from Changhai and Huashan Hospital, respectively, between 2011 and 2020. A visual analog scale (range 0–10) was utilized to evaluate satisfaction with anal function and quality of life. The anal function was evaluated with Wexner scores and low anterior resection syndrome (LARS) score. Quality of life was evaluated with the EORTC QLQ-C30 and QLQ-CR38.ResultsThe CSPO group had more male patients (65.8% vs. 50%, p = 0.042), more preoperative chemoradiotherapy (33.3% vs. 10.6%, p < 0.001), lower tumor position (3.45 ± 1.13 vs. 4.24 ± 0.86 cm, p < 0.001), and more postoperative chemotherapy (65% vs. 13.6%, p < 0.001) compared to the ISR group. In addition, CSPO patients had shorter postoperative stay (6.63 ± 2.53 vs. 7.85 ± 4.73 days, p = 0.003) and comparable stoma reversal rates within 1 year after surgery (92.16% vs. 96.97%, p = 0.318). Multivariable analysis showed that CSPO significantly contributed to higher satisfaction with anal function (beta = 1.752, 95% CI 0.776–2.728) and with quality of life (beta = 1.219, 95% CI 0.374–2.064), but not to Wexner, LARS score, or EORTC QLQ-C30 and QLQ-CR38.ConclusionCSPO improved the satisfaction with anal function and quality of life but utilized more preoperative chemoradiotherapy. CSPO may be an alternative choice for patients with very low rectal cancers in better physical health and with higher requirements for anal function and quality of life.

Comparison of functional and oncological outcome of conformal sphincter preservation operation, low anterior resection, and abdominoperineal resection in very low rectal cancer: a retrospective comparative cohort study with propensity score matching.

Conformal sphincter preservation operation (CSPO) procedure is a sphincter preservation procedure for preserving the anal canal function for very low rectal cancers. This study investigated the functional and oncological outcome of conformal sphincter preservation operation by comparing with low anterior resection (LAR) and abdominoperineal resection (APR). This is a retrospective comparative study. Patients who received conformal sphincter preservation operation (n=52), low anterior resection (n=54), or abdominoperineal resection (n=69) were included between 2011 and 2016 in a tertiary referral hospital. Propensity score matching was applied to adjust the baseline characteristics which may influence the choice of the surgical procedure. Twenty-one pairs of conformal sphincter preservation operation vs. low anterior resection and 29 pairs of conformal sphincter preservation operation vs. abdominoperineal resection were selected. The first group had a higher tumor location than the second group. Compared with the low anterior resection group, the conformal sphincter preservation operation group had shorter distal resection margins; however, no significant differences were identified in daily stool frequency, Wexner incontinence score, local recurrence, distant metastasis, overall survival, and disease-free survival between both groups. Compared with the abdominoperineal resection group, the conformal sphincter preservation operation group had shorter operative time and shorter postoperative hospital stay. No significant differences were identified in local recurrence, distant metastasis, overall survival, and disease-free survival. Conformal sphincter preservation operation is oncologically safe compared to APR and LAR, and has similar functional findings to LAR. Studies comparing CSPO with intersphincteric resection should be performed.

Low anterior resection syndrome.

Low anterior resection syndrome (LARS) is the distressful defecatory functional problem after sphincter-saving surgery for rectal cancer. Although the symptoms of fecal urgency, frequency, and incontinence may develop in most of the patients after surgery, there is no definitive treatments for LARS. Multifactorial etiologies and various risk factors have been identified, but the reduction of storage capacity in the rectum is one of the main reasons for LARS. Anal sphincter muscle or nerve damage during rectoanal resection or anastomosis construction, and intersphincteric resection for low-lying tumors or hand-sewing anastomosis, are the absolute risk factors for LARS. Preoperative radiotherapy, postoperative complications, such as anastomosis leakage, or longer duration of stoma, are also risk factors. The severity of LARS can be confirmed using the LARS score questionnaire. The questionnaire has been translated to numerous language versions including Korean and have been validated. Diverse empirical treatments, such as loperamide, fiber, probiotics, or enema, have been tried, but the safety and efficacy have not been verified yet. The 5-Hydroxytryptamine (5-HT) receptor antagonist, ramosetron, used for diarrhea-dominant irritable bowel syndrome, is one potential drug for relieving the symptoms of major LARS. A randomized-controlled trial suggested the use of ramosetron could be safe and efficacious for patients who have major LARS after sphincter-saving rectal cancer surgery. Novel techniques or drugs for relieving the symptoms of LARS should be developed more and further studies are necessary.

Transanal Conformal Resection Is Associated with a Better Postoperative Anorectal Function Compared with Intersphincteric Resection for Low Rectal Cancer

Transanal Conformal Resection Is Associated with a Better Postoperative Anorectal Function Compared with Intersphincteric Resection for Low Rectal Cancer