Transanal Transection and Single-Stapled Anastomosis (TTSS): A comparison of anastomotic leak rates with the double-stapled technique and with transanal total mesorectal excision (TaTME) for rectal cancer.

BACKGROUND: in the literature on rectal cancer (RC) surgery many studies have focused on the quality of total mesorectal excision (TME) dissection, while there is a scarcity of comparative data on transection and anastomosis. No anastomosis has so far proved to be superior to any other. The aim of this study was to compare anastomotic leak (AL) rates between conventional laparoscopic double-stapled (DS), transanal total mesorectal excision (TaTME) and Transanal Transection and Single-Stapled anastomosis (TTSS) techniques. METHODS: consecutive mid-low RC patients undergoing elective laparoscopic TME with stapled anastomosis and protective stoma, by either DS, TaTME or TTSS techniques were retrieved from a prospectively collected database. RESULTS: 127 DS; 100 TaTME and 50 TTSS were included. Demographics, distance of the tumor from anal verge and neoadjuvant therapy were comparable. Operative time was longer in TaTME over DS and TTSS (p < 0.0001). More 90-days complications occurred in DS group vs TTSS (p = 0.029). The AL rate was 17.5% in DS, 6% in TaTME and 2% in TTSS group (p = 0.005). AL grade was: one B (2%) in TTSS; 2 grade B (2%) and 4 grade C (4%) in TaTME; 6 grade A (4.7%), 7 grade B (5.5%) and 9 grade C (7.1%) in DS group. Reintervention rate after AL was higher in DS group over TTSS (12.6% vs 2%; p = 0.003). The rate of stoma closure, pathology data and margin positivity did not differ. CONCLUSIONS: TTSS strategy is feasible, safe and leads to very low AL rates after TME for RC.

Short-term clinical outcomes of a European training programme for robotic colorectal surgery.

BACKGROUND: Despite there being a considerable amount of published studies on robotic colorectal surgery (RCS) over the last few years, there is a lack of evidence regarding RCS training pathways. This study examines the short-term clinical outcomes of an international RCS training programme (the European Academy of Robotic Colorectal Surgery-EARCS). METHODS: Consecutive cases from 26 European colorectal units who conducted RCS between 2014 and 2018 were included in this study. The baseline characteristics and short-term outcomes of cases performed by EARCS delegates during training were analysed and compared with cases performed by EARCS graduates and proctors. RESULTS: Data from 1130 RCS procedures were collected and classified into three cohort groups (323 training, 626 graduates and 181 proctors). The training cases conversion rate was 2.2% and R1 resection rate was 1.5%. The three groups were similar in terms of baseline characteristics with the exception of malignant cases and rectal resections performed. With the exception of operative time, blood loss and hospital stay (training vs. graduate vs. proctor: operative time 302, 265, 255 min, p < 0.001; blood loss 50, 50, 30 ml, p < 0.001; hospital stay 7, 6, 6 days, p = 0.003), all remaining short-term outcomes (conversion, 30-day reoperation, 30-day readmission, 30-day mortality, clinical anastomotic leak, complications, R1 resection and lymph node yield) were comparable between the three groups. CONCLUSIONS: Colorectal surgeons learning how to perform RCS under the EARCS-structured training pathway can safely achieve short-term clinical outcomes comparable to their trainers and overcome the learning process in a way that minimises patient harm.

Mesentery - a 'New' organ.

The mesentery is the organ in which all abdominal digestive organs develop, and which maintains these in systemic continuity in adulthood. Interest in the mesentery was rekindled by advancements of Heald and Hohenberger in colorectal surgery. Conventional descriptions hold there are multiple mesenteries centrally connected to the posterior midline. Recent advances first demonstrated that, distal to the duodenojejunal flexure, the mesentery is a continuous collection of tissues. This observation explained how the small and large intestines are centrally connected, and the anatomy of the associated peritoneal landscape. In turn it prompted recategorisation of the mesentery as an organ. Subsequent work demonstrated the mesentery remains continuous throughout development, and that abdominal digestive organs (i.e. liver, spleen, intestine and pancreas) develop either on, or in it. This relationship is retained into adulthood when abdominal digestive organs are directly connected to the mesentery (i.e. they are 'mesenteric' in embryological origin and anatomical position). Recognition of mesenteric continuity identified the mesenteric model of abdominal anatomy according to which all abdominal abdomino-pelvic organs are organised into either a mesenteric or a non-mesenteric domain. This model explains the positional anatomy of all abdominal digestive organs, and associated vasculature. Moreover, it explains the peritoneal landscape and enables differentiation of peritoneum from the mesentery. Increased scientific focus on the mesentery has identified multiple vital or specialised functions. These vary across time and in anatomical location. The following review demonstrates how recent advances related to the mesentery are re-orientating the study of human biology in general and, by extension, clinical practice.

The split scar sign as an indicator of sustained complete response after neoadjuvant therapy in rectal cancer.

OBJECTIVES: To measure the diagnostic performance of a new radiologic pattern on restaging magnetic resonance (MR) high-resolution T2-weighted imaging (T2-WI)-the split scar sign-for the identification of sustained complete response (SCR) after neoadjuvant therapy in rectal cancer. METHODS: Institutional review board approval was obtained for this retrospective study and the informed consent requirement was waived. Fifty-eight consecutive patients with rectal cancer who underwent neoadjuvant therapy were enrolled. Two radiologists blindly and independently reviewed restaging pelvic MR imaging and recorded the presence/absence of the split scar sign (mrSSS). On a second round, they also assessed the relative proportion of intermediate signal intensity on T2-WI (mrT2) and of high signal intensity on high b-value diffusion-weighted imaging (mrDWI). Endoscopic response grading records were retrieved. Qui-square test was employed in search for associations between SCR, defined as pathologic complete response or long-term recurrence-free clinical follow-up, and mrSSS, mrT2, mrDWI and endoscopy. Interobserver agreement for imaging parameters was estimated using Cohen's kappa (k). RESULTS: mrSSS was significantly associated with SCR, with specificity = 0.97/0.97, sensitivity = 0.52/0.64, PPV = 0.93/0.94, NPV = 0.73/0.78, and AuROC = 0.78/0.83, for observers 1/2, respectively. mrDWI was significantly associated with SCR for observer 2, with specificity = 0.76, sensitivity = 0.60, PPV = 0.65, NPV = 0.71, and AuROC = 0.69. mrT2 and endoscopy were not discriminative. Interobserver agreement was substantial for mrSSS (k = 0.69), moderate for mrDWI (k = 0.46), and poor for mrT2 (k = 0.17). CONCLUSION: The split scar sign is a simple morphologic pattern visible on restaging T2-WI which, although not sensitive, is very specific for the identification of sustained complete responders after neoadjuvant therapy in rectal cancer. KEY POINTS: • The split scar sign is a morphologic pattern visible on high-resolution T2-weighted MR imaging in rectal cancer patients after neoadjuvant therapy. It therefore does not require any changes to standard protocol. • At first restaging pelvic MR imaging (mean: 9.1 weeks after the end of radiotherapy), the split scar sign identified patients who sustained a complete response with very high specificity (0.97) and positive predictive value (0.93-0.94). • The split scar sign has the potential to improve patient selection for "watch-and-wait" after neoadjuvant therapy in rectal cancer.

Salvage surgery for local regrowths in Watch & Wait - Are we harming our patients by deferring the surgery?

BACKGROUND: Rectal cancer surgery conveys significant morbidity/mortality, long-term functional impairment and urinary & sexual dysfunction, especially if associated with neoadjuvant chemoradiotherapy (ChRT). Watch & Wait (W&W) is gaining momentum as an option for patients with clinical complete response (cCR) after ChRT. Approximately 30% will develop a local regrowth (RG) and need deferred surgery. Our study aimed to assess the short-term clinical outcomes after surgery for regrowths. PATIENTS AND METHODS: Consecutive rectal cancer patients from a tertiary institution who underwent neoadjuvant ChRT, between January 2013 and October 2018, were identified from a prospectively maintained database. Patients with RG under W&W surveillance were operated - regrowth deferred surgery (RDS) group - and compared to those with persistent disease after ChRT who did undergo surgery - non-deferred surgery (NDS) group. RESULTS: Total of 124 patients received neoadjuvant treatment: 46 (37%) underwent surgery for persistent disease; 78 (63%) with cCR entered W&W. Twenty three developed RG and underwent surgery, while 55 remain under surveillance. RDS group had lower tumors than NDS group (2.3 cm ±â€¯2 vs 4.5 cm ±â€¯3, p = 0.002). All RG underwent minimally invasive surgery (MIS). Anastomotic leaks, 30-day morbidity, reintervention and readmission rates were similar. Pathology features and 3-year oncological outcomes were identical between groups. CONCLUSION: Patients with initial cCR and local regrowth may be safely managed by deferred surgery. Short-term outcomes suggest equivalent results to patients with incomplete clinical response and immediate radical surgery. Delayed MIS appears to have no negative impact on oncological outcomes.

The Future of Rectal Cancer Surgery: A Narrative Review of an International Symposium.

Surgery remains the mainstay of curative treatment for primary rectal cancer. For mid and low rectal tumors, optimal oncologic surgery requires total mesorectal excision (TME) to ensure the tumor and locoregional lymph nodes are removed. Adequacy of surgery is directly linked to survival outcomes and, in particular, local recurrence. From a technical perspective, the more distal the tumor, the more challenging the surgery and consequently, the risk for oncologically incomplete surgery is higher. TME can be performed by an open, laparoscopic, robotic or transanal approach. There is a lack of consensus on the "gold standard" approach with each of these options offering specific advantages. The International Symposium on the Future of Rectal Cancer Surgery was convened to discuss the current challenges and future pathways of the 4 approaches for TME. This article reviews the findings and discussion from an expert, international panel.

Oncological and Survival Outcomes in Watch and Wait Patients With a Clinical Complete Response After Neoadjuvant Chemoradiotherapy for Rectal Cancer: A Systematic Review and Pooled Analysis.

OBJECTIVE: The aim of this study was to evaluate the oncological and survival outcomes of a Watch and Wait policy in rectal cancer after a clinical complete response (cCR) following neoadjuvant chemoradiotherapy. BACKGROUND: The detection of a cCR after neoadjuvant treatment may facilitate a nonoperative approach in selected patients. However, the long-term safety of this strategy remains to be validated. METHOD: This is a systematic review of the literature to determine the oncological outcomes in Watch and Wait patients. The primary outcome was the cumulative rate of local regrowth, success of salvage surgery, and incidence of metastases. We also evaluated survival outcomes. A pooled analysis of manually extracted summary statistics from individual studies was carried out using inverse variance weighting. RESULTS: Seventeen studies comprising 692 patients were identified; incidence of cCR was 22.4% [95% confidence interval (CI),14.3-31.8]. There were 153 (22.1%) local regrowths, of which 96% (n = 147/153) manifested in the first 3 years of surveillance. The 3-year cumulative risk of local regrowth was 21.6% (95% CI, 16.0-27.8). Salvage surgery was performed in 88% of patients, of which 121 (93%) had a complete (R0) resection. Fifty-seven metastases (8.2%) were detected, and 35 (60%) were isolated without evidence of synchronous regrowths; 3-year incidence was 6.8% (95% CI, 4.1-10.2). The 3-year overall survival was 93.5% (95% CI, 90.2-96.2). CONCLUSION: In rectal cancer patients with a cCR following neoadjuvant chemoradiotherapy, a Watch and Wait policy appears feasible and safe. Robust surveillance with early detection of regrowths allows a high rate of successful salvage surgery, without an increase in the risk of systemic disease, or adverse survival outcomes.

Delaying surgery after neoadjuvant chemoradiotherapy in rectal cancer has no influence in surgical approach or short-term clinical outcomes.

AIMS: In rectal cancer, increasing the interval between the end of neoadjuvant chemoradiotherapy (CRT) and surgery could improve the pathological complete response (pCR) rates, allow full-dose neoadjuvant chemotherapy, and select patients with a clinical complete response (cCR) for inclusion in a "watch & wait" program (W&W). However, controversy arises from waiting more than 8-12 weeks after CRT, as it might increase fibrosis around the total mesorectal excision (TME) plane potentially leading to technical difficulties and higher surgical morbidity. This study evaluates the type of surgical approach and short term post-operative outcomes in patients with rectal cancer that were operated before and after 12 weeks post CRT. METHODS: Patients from three centres (two in the UK, one in Portugal) who received rectal cancer surgery following neoadjuvant CRT between 2007 and 2016 were identified from prospectively maintained databases. Preoperative CRT was given to patients with high risk for local recurrence (threatened CRM ≤2 mm or T4 in staging MRI). The baseline characteristics and surgical outcomes of patients that were operated <12 weeks and ≥12 weeks after finishing CRT were analysed. RESULTS: A total of 470 patients received rectal cancer surgery, of those 124 (26%) received neoadjuvant CRT. Seventy-six patients (61%) were operated ≥12 weeks after end of neoadjuvant-CRT and 48 < 12 weeks. Patients in the ≥12 weeks cohort had a higher BMI (27 vs 25, p = 0.030) and lower lymph node yield (11 vs 14, p = 0.001). The remaining of the baseline characteristics were similar between the two groups (age, operating surgeon, gender, ASA grade, T stage, surgical approach, operation). Operation time, blood loss, conversion rate, length of stay, 30-day readmission rate, 30-day reoperation rate, anastomotic leak rate, 30-day mortality, CRM clearance, and ypT0 rates were similar between the two groups. Univariate and multivariate analysis showed that delaying surgery ≥12 weeks did not affect morbidity and mortality. CONCLUSION: In our cohort, there was no difference in short term surgical outcomes between patients operated before or after 12 weeks following CRT. The type of surgical procedures and the proposed approach did not differ due to waiting after CRT. Delaying surgery by ≥ 12 weeks is safe, feasible and does not result in higher surgical morbidity.

Local Excision Techniques for Rectal Cancer After Neoadjuvant Chemoradiotherapy: What Are We Doing?

BACKGROUND: Recent evidence shows that the majority of rectal cancers demonstrate occult tumor scatter after neoadjuvant chemoradiotherapy that can extend for several centimeters under adjacent normal-appearing mucosa beside the residual mucosal abnormality or scar. OBJECTIVE: This systematic review aimed to determine all of the published selection criteria and technical descriptions for local excision to date with regard to this phenomenon. DATA SOURCES: PubMed, MEDLINE, and Embase were searched using the following key words: rectal cancer, local excision, radiotherapy, and neoadjuvant. STUDY SELECTION: Studies that assessed local excision of rectal cancer after neoadjuvant chemoradiotherapy were included. Duplicate series were excluded from final analysis. INTERVENTION: All of the data points were tabulated and analyzed using Microsoft Excel. MAIN OUTCOME MEASURES: Criteria for patient selection, surgical technique, clinical restaging, pathologic assessment, and indications for completion surgery were analyzed. RESULTS: After exclusions, data from 25 studies that in total evaluated local excision in 1001 patients were included. Compared with the single accepted technique of total mesorectal excision, described techniques for local excision after neoadjuvant therapy demonstrate significant variability in many critical technical issues, such as marking/tattooing original tumor margins before neoadjuvant therapy, using pretreatment tumor size/stage as exclusion criteria, and specifically stating lateral excision margins. Where detailed, the majority of local recurrences occurred in patients with clear pathological margins, yet significant variation existed for pathological assessment and reporting, with few studies detailing R status and some not reporting margin status at all. Significant variability also existed for adverse tumor features that mandated completion surgery, and, importantly, many series describe patients refusing completion surgery where indicated. LIMITATIONS: We were unable to perform meta-analysis because studies lacked sufficient methodologic homogeneity to synthesize. CONCLUSIONS: The observations from this study prompt additional study, standardization of technique, and cautious use of local excision of rectal cancer in the setting of neoadjuvant chemoradiotherapy.

An ontogenetic approach to gynecologic malignancies.

UNLABELLED: Ontogenetic anatomy is the mapping of body compartments established during early embryologic development, particularly well demarcated in the adult pelvis. Traditional cancer surgery is based on wide tumour excision with a safe margin, whereas the ontogenetic theory of local tumour spread claims that local dissemination is facilitated in the ontogenetic compartment of origin, but suppressed at its borders in the early stages of cancer development. Optimal local control of cancer is achieved by whole compartment resection with intact margins following ontogenetic "planes". The principles embodied in this hypothesis are most convincingly supported by the results of the implementation of total mesorectal excision in rectal cancer, and more recently, by innovative surgical approaches to gynaecologic malignancies. The high resolution contrast of MR, accurately delineating pelvic fascial compartments, makes it the best imaging modality for gynaecologic cancer surgery planning following these principles, but requires interpretation of imaging anatomy from a different perspective. TEACHING POINTS: • Ontogenetic anatomy refers to mapping of embryologically determined body compartments. • Ontogenetic theory claims tumour growth is not isometrical, but rather compartment permissive. • Ontogenetic principles are highly supported by the outcome results of total mesorectal excision. • Innovative gynaecologic cancer surgery approaches based on ontogenetic theory show promising results.

Transanal Total Mesorectal Excision for Rectal Cancer: Outcomes after 140 Patients.

BACKGROUND: The anatomic difficulties that we have to deal with in open surgery for rectal cancer have not been overcome with the laparoscopic approach. In the search for a solution, a change of concept arose: approaching the rectum from below. The main objectives of this study were to show the potential advantages of the hybrid transabdominal-transanal total mesorectal excision (taTME). This approach may improve quality of the mesorectal specimens. Second, proctectomy can be technically easier and more safely performed "down to up," which would result in shorter surgical times, lower conversion rates, and less morbidity. STUDY DESIGN: A prospective series of hybrid taTME was conducted from October 2011 to November 2014. RESULTS: During the study period, 140 procedures were performed. Mean operative time was 166 minutes. There were no conversions or intraoperative complications. Macroscopic quality assessment of the resected specimen was complete in 97.1% and nearly complete in 2.1%. Thirty-day morbidity was minor (Clavien-Dindo I + II) in 24.2% and major (Clavien-Dindo III + IV) in 10 %. No patient died within the first 30 days postsurgery (Clavien-Dindo V). The mean follow-up was 15 months, with a 2.3% local recurrence rate and a 7.6% rate of systemic recurrence. CONCLUSIONS: Pathologic analysis showed a very good macroscopic quality of TME specimens, which is the most important prognostic factor in rectal cancer. Intraoperative outcomes regarding conversion, surgical times, and intraoperative complications are very satisfactory. Short-term morbidity and oncologic outcomes are as good as in other laparoscopic TME series.

The prognostic significance of postchemoradiotherapy high-resolution MRI and histopathology detected extramural venous invasion in rectal cancer.

OBJECTIVE: This study aimed to determine the prognostic significance of extramural venous invasion (EMVI) after chemoradiotherapy (CRT) by both magnetic resonance imaging (MRI) (ymrEMVI) and histopathology (ypEMVI). BACKGROUND: EMVI is a prognostic factor in rectal cancer but whether this remains so after CRT preoperative is unknown. Histopathological definitions of EMVI are variable and lead to underreporting particularly after CRT. METHODS: All consecutive patients staged on initial MRI as EMVI-positive undergoing preoperative CRT and curative surgery between Jan 2006 and Jan 2012 were included. Posttreatment EMVI status (yEMVI) was reevaluated for both MRI and pathology. The primary endpoint of disease-free survival (DFS) for ymrEMVI and ypEMVI was calculated using the Kaplan-Meier product limit and compared with a Mantel-Cox log-rank test. A P < 0.05 was considered significant. Hazard ratios (HRs) for disease recurrence were generated using Cox proportional hazard regression for MRI and histopathology tumor characteristics. RESULTS: A total of 188 patients who had evidence of EMVI on initial baseline MRI staging were included. MRI detected significantly more patients with persistent EMVI than histopathology (53% vs 19%) but both were prognostic for worse survival-ymrEMVI (HR 1.97) and ypEMVI (HR 2.39). Patients with persistent ymrEMVI-positivity had significantly worse DFS at 3 years (42.7%) compared with ymrEMVI-negative tumors (79.8%); DFS for was 36.9% versus 65.9% positive and negative ypEMVI, respectively. CONCLUSIONS: Detection of EMVI post-CRT is prognostically significant whether detected by MRI or histopathology. EMVI status after treatment may be used to counsel patients regarding ongoing risks of metastatic disease, implications for surveillance, and systemic chemotherapy.

Preoperative magnetic resonance imaging assessment of circumferential resection margin predicts disease-free survival and local recurrence: 5-year follow-up results of the MERCURY study.

PURPOSE: The prognostic relevance of preoperative high-resolution magnetic resonance imaging (MRI) assessment of circumferential resection margin (CRM) involvement is unknown. This follow-up study of 374 patients with rectal cancer reports the relationship between preoperative MRI assessment of CRM staging, American Joint Committee on Cancer (AJCC) TNM stage, and clinical variables with overall survival (OS), disease-free survival (DFS), and time to local recurrence (LR). PATIENTS AND METHODS: Patients underwent protocol high-resolution pelvic MRI. Tumor distance to the mesorectal fascia of ≤ 1 mm was recorded as an MRI-involved CRM. A Cox proportional hazards model was used in multivariate analysis to determine the relationship of MRI assessment of CRM to survivorship after adjusting for preoperative covariates. RESULTS: Surviving patients were followed for a median of 62 months. The 5-year OS was 62.2% in patients with MRI-clear CRM compared with 42.2% in patients with MRI-involved CRM with a hazard ratio (HR) of 1.97 (95% CI, 1.27 to 3.04; P < .01). The 5-year DFS was 67.2% (95% CI, 61.4% to 73%) for MRI-clear CRM compared with 47.3% (95% CI, 33.7% to 60.9%) for MRI-involved CRM with an HR of 1.65 (95% CI, 1.01 to 2.69; P < .05). Local recurrence HR for MRI-involved CRM was 3.50 (95% CI, 1.53 to 8.00; P < .05). MRI-involved CRM was the only preoperative staging parameter that remained significant for OS, DFS, and LR on multivariate analysis. CONCLUSION: High-resolution MRI preoperative assessment of CRM status is superior to AJCC TNM-based criteria for assessing risk of LR, DFS, and OS. Furthermore, MRI CRM involvement is significantly associated with distant metastatic disease; therefore, colorectal cancer teams could intensify treatment and follow-up accordingly to improve survival outcomes.

Can a novel MRI staging system for low rectal cancer aid surgical planning?

BACKGROUND: Low rectal cancers are associated with worse outcomes in comparison with mid and upper rectal tumors. OBJECTIVE: This study aimed to assess the predictive accuracy of MRI in identifying the correct surgical approach based on the mesorectal and extralevator planes. DESIGN: This study involved the retrospective analysis of MRI and histopathology data of 33 patients with low rectal cancer, with the use of an anatomically based staging system. Three radiologists reported on the available surgical planes of excision based on the predicted relationship of tumor to key anatomical features. MRI-predicted planes of excision were then compared with the histopathological planes actually required, with the use of the same staging criteria. SETTINGS: The study was conducted at 4 English district general hospitals. PATIENTS: Unselected patients with low rectal cancer, all of whom were participants in a multicenter study, were eligible for this study. MAIN OUTCOME MEASURES: : The main outcome measured was the accuracy of operative plane prediction on MRI. RESULTS: : On pathological analysis, the mesorectal plane would have been sufficient to achieve a clear margin in 28 of 33 (84.9%) of cases. The extralevator plane was required in 5 of 33 (15.1%). Planes were correctly predicted by MRI in 29 of 33 cases by radiologist 1 and 24 of 33 cases by radiologists 2 and 3 with an accuracy of 87.9% and 72.7%. Overstaging (extralevator plane predicted when a mesorectal plane would have sufficed) occurred in 3 of 33 and 7 of 33 cases. Understaging (mesorectal plane predicted when an extralevator plane was required) occurred in 1 of 33 and 2 of 33 cases. The positive and negative predictive values of MRI in determining the histopathological plane of excision required were 57% and 96% for radiologist 1 and 30% and 91% for radiologists 2 and 3. LIMITATIONS: This study was limited by its retrospective nature and its relatively small patient numbers. No account was taken of postoperative function when recommending the surgical plane. CONCLUSIONS: This supports an anatomically based MRI staging system for low rectal cancer to predict the planes of surgical excision. This may help to reduce margin positivity and to improve outcome in patients with low rectal cancer.

Deep pelvic anatomy revisited for a description of crucial steps in extralevator abdominoperineal excision for rectal cancer.

BACKGROUND: Extralevator abdominoperineal excision results in superior oncologic outcome for advanced low rectal cancer. The exact definition of surgical resection planes is pivotal to achieving negative circumferential resection margins. OBJECTIVE: This study aims to describe the surrounding anatomical structures that are at risk for inadvertent damage during extralevator abdominoperineal excision. DESIGN AND SETTING: Joint surgical and macroanatomical dissection was performed in a university laboratory of clinical anatomy. METHODS: A stepwise dissection study was conducted according to the technique of extralevator abdominoperineal excision by abdominal and perineal approaches in 4 human cadaveric pelvises. Muscular, fascial, tendinous, and neural structures were carefully exposed and related to the corresponding surgical resection planes. RESULTS: In addition to the autonomic nerves to be identified and preserved during total mesorectal excision, further structures endangered during extralevator abdominoperineal excision can be clearly identified. Terminal pudendal nerve branches come close to the surgical resection plane at the outer surface of the puborectal sling. Likewise, the pelvic plexus and its neurovascular bundles embedded within the parietal pelvic fascia extend close to the apex of the prostate where the parietal pelvic fascia has to be divided. These neural structures converge in the region of the perineal body, an area that provides no "self-opening" planes for surgical dissection. Thus, the necessity to sharply detach the anorectal specimen anteriorly from the perineal body and the superficial transverse perineal muscle bears the risk of both inadvertent damage of the aforementioned anatomical structures and perforation of the specimen. LIMITATIONS: The study focused primarily on the macroscopic topography relevant to the surgical procedure, so that previously published histologic examinations were not performed. CONCLUSION: The present anatomical dissection study highlights those anatomical landmarks that require clear identification for the successful achievement of both negative circumferential resection margins and preservation of urogenital functions during extralevator abdominoperineal excision.