International standardization and optimization group for intersphincteric resection (ISOG-ISR): modified Delphi consensus on anatomy, definition, indication, surgical technique, specimen description and functional outcome

A Porcine Model of Laparoscopic Intersphincteric Resection for Ultra-Low Rectal Cancer

OBJECTIVE

To develop a porcine model for laparoscopic intersphincteric resection (ISR) targeting ultra-low rectal cancer.

METHODS

Six Bama mini-pigs underwent a standard laparoscopic ISR procedure: (1) Ligation and transection of the inferior mesenteric vessels; (2) Exposure and sparing of the pelvic autonomic nerves; (3) Dissection of the rectum; (4) Dissection and transection of hiatal ligament and rectourethralis muscle; (5) Transanal dissection of the anal canal; (6) Dissection of the intersphincteric space (ISS); (7) End-to-end handsewn coloanal anastomosis (CAA). Pathological evaluations were conducted to ascertain the precision of the ISR. Furthermore, postoperative fecal incontinence scores were systematically assessed on a weekly basis throughout a 12-week post-surgery follow-up period.

RESULTS

All six pigs survived surgery without conversion to an open approach. There were no occurrences of incisional infection or any surgical complications, including anastomotic leakage, anastomotic bleeding, or ileus. Postoperatively, one pig manifested constipation and three exhibited anal redness, both conditions ameliorating within a week. No erosive ulcers were detected. Notably, all animals exhibited fecal staining on their tails within the first two weeks post-surgery, transitioning to formed feces by the third week. Improvement in defecation frequency was observed after 6 weeks, with a noticeable reduction in defecation areas after one month. Incontinence scores, evaluated three months post ISR surgery, revealed no significant abnormalities in anal function compared to preoperative assessments.

CONCLUSIONS

This study established a replicable porcine model for laparoscopic ISR, demonstrating its potential utility in clinical and fundamental research related to ultra-low rectal cancer treatment.

[Surgical anatomy of the anorectum]

The anorectum corresponds to the last segment of the gastrointestinal tract and is responsible for mediating fecal continence and controlled defecation. An understanding of the complex topographic anatomy is an indispensable prerequisite for the surgical treatment of benign and malignant diseases in the anorectal region. The detailed description of perirectal fascia, anorectal blood supply and lymph vessel drainage, pelvic autonomic nerves and components of the anal canal and anal sphincter complex has significantly contributed to improvement of the oncological and functional surgical outcome. In this article the state of knowledge relating to the anorectal anatomy is outlined providing a practical basis for rectal and proctological surgical procedures.

Short-term outcomes of transanal endoscopic intersphincteric resection for locally advanced rectal cancer after neoadjuvant chemoradiotherapy: A single-center retrospective cohort study

OBJECTIVE

To compare the perioperative safety and specimen characteristics after transanal endoscopic intersphincteric resection (taE-ISR) versus classical intersphincteric resection (cISR) in patients with locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT).

METHODS

Clinicopathological data of 145 patients (75 undergoing taE-ISR and 70 undergoing cISR after nCRT) were retrospectively analyzed. Baseline characteristics, perioperative details, and pathological specimen quality of the two groups were compared.

RESULTS

Intraoperative blood loss was lower in the taE-ISR group compared to cISR (50.0 (40.0-100.0) ml vs. 70.0 (50.0-100.0) ml, P = 0.034). Two patients (2.6 %) in the taE-ISR group and eight patients (11.4 %) in the cISR group sustained adjacent organ injury (P = 0.037). There was no statistically significant difference in the prevalence of postoperative complications between the two groups (17.3 % vs. 30.0 %, P = 0.072). However, pelvic abscess (1.3 % vs. 8.6 %, P = 0.042) and rectovaginal fistula (0.0 % vs. 5.7 %, P = 0.036) occurred less often in taE-ISR compared to cISR. The complete resection rate was higher in taE-ISR compared to cISR (98.7 % vs. 91.4 %, P = 0.042). No patients in taE-ISR had positive distal resection margins (DRM), while four patients in cISR had positive DRM (0.0 % vs. 5.7 %, P = 0.036).

CONCLUSION

taE-ISR after nCRT was associated with higher-quality specimens, reduced intraoperative blood loss, and fewer perioperative complications, attesting to the feasibility and safety of taE-ISR In low-LARC patients.

Long-term functional and prognostic outcomes of robotic intersphincteric resection for treating low rectal cancer: a single-center retrospective study

OBJECTIVE

Intraoperative and postoperative data collected from patients with low rectal cancer who had undergone robotic and laparoscopic intersphincteric resection (ISR) procedures were retrospectively analyzed to evaluate factors linked to anastomotic leakage and postoperative recovery of urinary function, bowel control, and long-term prognosis.

METHOD

This single-center study enrolled patients with low rectal cancer who had undergone robotic ISR (n = 150) or laparoscopic ISR (n = 150) from January 2016 to July 2019.

RESULT

The respective mean tumor distances from the anal margin in the robotic and laparoscopic ISR groups were 3.94 ± 0.48 cm and 5.66 ± 0.47 cm, while the mean times to postoperative catheter removal in these respective groups were 4.9 ± 1.4 days and 5.3 ± 1.6 days (P = 0.007). Binary logistic regression analyses indicated that a higher BMI (≥ 25 kg/m2), diabetes, the absence of left colic artery presentation, T3 pathological T stage, the absence of temporary ileostomy, and DRM (distal resection margin) < 1 cm were linked to a greater likelihood of postoperative anastomotic leakage. Relative to patients in the laparoscopic group, those in the robotic ISR group exhibited better anal and urinary function from 6 months postoperatively, as indicated by a lower frequency of bowel movements, reduced LARS (The Low Anterior Resection Syndrome) severity, and lower IPSS (the International Prostate Symptom Score) scores. Five-year overall and disease-free survival did not differ significantly between the groups.

CONCLUSION

These results highlight the promise of robotic ISR as an approach to managing cases of low and ultra-low rectal tumors, providing a safe and feasible alternative to conventional laparoscopic ISR treatment.

Mastering rectal cancer MRI: From foundational concepts to optimal staging

MRI plays a critical role in the local staging, restaging, surveillance, and risk stratification of patients, ensuring they receive the most tailored therapy. As such, radiologists must be familiar not only with the key MRI findings that influence management decisions but also with the appropriate MRI protocols and structured reporting. Given the complexity of selecting the optimal therapy for each patient-which often requires multidisciplinary discussions-radiologists should be well-versed in relevant treatment strategies and surgical terms, understanding their significance in guiding patient care. In this manuscript, we review the most common treatment options for managing patients with rectal adenocarcinoma, emphasizing key MRI principles and protocol characteristics for accurate staging. We also highlight important anatomical landmarks and essential factors to be described during baseline assessment. Additionally, we discuss crucial information for restaging and surveillance.

MRI of the Rectum: A Decade into DISTANCE, Moving to DISTANCED

Over the past decade, advancements in rectal cancer research have reshaped treatment paradigms. Historically, treatment for locally advanced rectal cancer has focused on neoadjuvant long-course chemoradiotherapy, followed by total mesorectal excision. Interest in organ preservation strategies has been strengthened by the introduction of total neoadjuvant therapy with improved rates of complete clinical response. The administration of systemic induction chemotherapy and consolidation chemoradiotherapy in the neoadjuvant setting has introduced a new dimension to the treatment landscape and patients now face a more intricate decision-making process, given the expanded therapeutic options. This complexity underlines the importance of shared decision-making and brings to light the crucial role of radiologists. MRI, especially high-spatial-resolution T2-weighted imaging, is heralded as the reference standard for rectal cancer management because of its exceptional ability to provide staging and prognostic insights. A key evolution in MRI interpretation for rectal cancer is the transition from the DISTANCE mnemonic to the more encompassing DISTANCED-DIS, distal tumor boundary; T, T stage; A, anal sphincter complex; N, nodal status; C, circumferential resection margin; E, extramural venous invasion; D, tumor deposits. This nuanced shift in the mnemonic captures a wider range of diagnostic indicators. It also emphasizes the escalating role of radiologists in steering well-informed decisions in the realm of rectal cancer care.

Intersphinktäre Resektion zum Schließmuskelerhalt beim ultratiefen Rektumkarzinom – Ein Update

Die Indikation zum Sphinktererhalt bei Patienten mit einem sehr tief sitzenden Rektumkarzinom ist in vielerlei Hinsicht eine Herausforderung und auch an die Beherrschung der intersphinktären Resektion gebunden. In dieser Arbeit sollen die zunehmend definierten Operationstechniken kurz vorgestellt und aktuell eingeordnet werden.

Robotic intersphincteric resection for low rectal cancer: a cumulative sum analysis for the learning curve

PURPOSE

This study aimed to assess the learning curve of robot-assisted intersphincteric resection for low rectal cancer.

METHODS

We retrospectively analyzed the clinical data of 89 patients who underwent robot-assisted intersphincteric resection. All surgeries were performed by the same group of surgeons at our institution between June 2016 and April 2021. The learning curve was evaluated using a cumulative sum analysis and the best-fit curve. The different stages of the learning curve were compared based on patient characteristics and short-term clinical outcomes to evaluate their impact on clinical efficacy.

RESULTS

The minimum number of cases required to overcome the learning curve was 47. The learning curve was divided into the learning improvement and proficiency stages. Significant differences were observed in the operation time and the number of lymph nodes between the two stages (P < 0.05), whereas no significant differences were found in intraoperative blood loss, first postoperative exhaust time, postoperative complications, 3-year progression-free survival, overall survival, and local recurrence-free survival (P > 0.05).

CONCLUSION

Robotic-assisted intersphincteric resection for low rectal cancer exhibits a learning curve that can be divided into two stages: namely, learning improvement and proficiency. Achieving proficiency requires a minimum of 47 surgical cases.

A New Approach to Ultra-Low Anterior Resection-Intersphincteric Dissection With Total Hiatal Ligament Excision for Very Low Rectal Cancer Located in the Posterior Wall of the Rectum: A More Satisfactory Technique for Local Recurrence Control

BACKGROUND

The hiatal ligament, as the anatomical landmark for the completion of total mesorectal excision (TME) for ultra-low rectal cancer, represents a continuation of the longitudinal muscle of the rectum. It receives vascular supply from the median sacral artery and contains lymphatic vessels. In cases where ultra-low rectal cancer is located in the posterior rectal wall, the hiatal ligament may theoretically serve as an anatomical region susceptible to direct tumor cell spread or distant metastasis.

OBJECTIVE

To evaluate the effect of circumferential tumor location (CTL) on postoperative survival of low rectal cancer and to determine the effect of total hiatal ligament excision (THLE) on the prognosis of patients with posterior rectal cancer.

METHODS

Patients with ultra-low rectal cancer who underwent laparoscopic surgery between March 2014 and October 2021 were enrolled in this study. Propensity score matching (PSM) analysis was used to compare the clinicopathological characteristics and prognosis of patients in the posterior group and the non-posterior group. Prognostic factors were identified using COX regression. PSM analysis was also used in the posterior tumor subgroup to compare the clinicopathological characteristics and prognosis of patients in the hiatal ligament traditional transection (HLTT) and THLE groups.

RESULTS

After PSM, OS, and DFS were comparable between the posterior and non-posterior groups. Similarly, no difference was noted in the local recurrence rate between the two groups (p = 0.23). The prognosis of ultra-low rectal cancer was not affected by CTL. However, the local recurrence rate was significantly lower in the THLE group compared with the HLTT group (p = 0.023). Multivariate analysis of the posterior group identified CRM, TNM stage III, and HLTT as independent risk factors for local recurrence-free survival.

CONCLUSIONS

CTL is not a prognostic risk factor for low rectal cancer. In posterior wall tumors, THLE significantly reduces the local recurrence rate for low rectal cancer.

MRI for Rectal Cancer: Updates and Controversies-AJR Expert Panel Narrative Review

Rectal MRI is a critical tool in the care of patients with rectal cancer, having established roles for primary staging, restaging, and surveillance. The comprehensive diagnostic and prognostic information provided by MRI helps to optimize treatment decision-making. However, challenges persist in the standardization and interpretation of rectal MRI, particularly in the context of rapidly evolving treatment paradigms, including growing acceptance of nonoperative management. In this AJR Expert Panel Narrative Review, we address recent advances and key areas of contention relating to the use of MRI for rectal cancer. Our objectives include: to discuss concepts regarding anatomic localization of rectal tumors; review the evolving rectal cancer treatment paradigm and implications for MRI assessment; discuss updates and controversies regarding rectal MRI for locoregional staging, restaging, and surveillance; review current rectal MRI acquisition protocols; and discuss challenges in homogenizing and optimizing acquisition parameters.

Determining the optimal distal resection margin in rectal cancer patients by imaging of large pathological sections: An experimental study

OBJECTIVE

To determine the distal resection margin in sphincter-sparing surgery in patients with low rectal cancer based on imaging of large pathological sections.

METHODS

Patients who underwent sphincter-sparing surgery for ultralow rectal cancer at Guangxi Medical University Cancer Hospital within the period from January 2016 to March 2022 were tracked and observed. The clinical and pathological data of the patients were collected and analyzed. The EVOS fluorescence automatic cell imaging system was used for imaging large pathological sections. Follow-up patient data were acquired mainly by sending the patients letters and contacting them via phone calls, and during outpatient visits.

RESULTS

A total of 46 patients (25 males, 21 females) aged 27 to 86 years participated in the present study. Regarding clinical staging, there were 9, 10, 16, and 10 cases with stages I, II, III, and IV low rectal cancer, respectively. The surgical time was 273.82 ± 111.51 minutes, the blood loss was 123.78 ± 150.91 mL, the postoperative exhaust time was 3.67 ± 1.85 days, and the postoperative discharge time was 10.36 ± 5.41 days. There were 8 patients with complications, including 3 cases of pulmonary infection, 2 cases of intestinal obstruction, one case of pleural effusion, and one case of stoma necrosis. The longest and shortest distal resection margins (distances between the cutting edges and the tumor edges) were 3 cm and 1 cm, respectively. The minimum length of the extension areas of the tumor lesions in the 46 images of large pathological sections was 0.1 mm, and the maximum length was 15 mm. Among the tumor lesions, 91.30% (42/46) had an extension area length of ≤5 mm, and 97.83% (45/46) had an extension area length of ≤10 mm. The length of the extension zone was not related to clinical pathological parameters (P > .05).

CONCLUSION

In the vast majority of cases, the distal resection margin was at least 1 cm; thus, "No Evidence of Disease" could have been achieved. Additional high-powered randomized trials are needed to confirm the results of the present study.

Intersphincteric resection following robotic-assisted versus laparoscopy-assisted total mesorectal excision for middle and low rectal cancer: a multicentre propensity score analysis of 1571 patients

BACKGROUND

Robotic-assisted total mesorectal excision (RaTME) may be associated with reduced conversion to an open approach and a higher rate of complete total mesorectal excision (TME); however, studies on its advantages in intersphincteric resection (ISR) are inadequate.

MATERIALS AND METHODS

This retrospective multicenter cohort study enroled consecutive patients who underwent RaTME and laparoscopy-assisted total mesorectal excision (LaTME) at four medical centres between January 2020 and March 2023. Propensity score matching (PSM), inverse probability of treatment weight (IPTW), and multivariate logistic regression analyses were performed. The primary outcome was the ISR rate. Secondary outcomes were coloanal anastomosis (CAA), conversion to open surgery, conversion to transanal TME, abdominoperineal resection, postoperative morbidity and mortality within 30 days, and pathological outcomes.

RESULTS

Among the 1571 patients, 1211 and 450 underwent LaTME and RaTME, respectively, with corresponding ISR incidences of 5.3% and 8.4% ( P =0.024). After PSM and IPTW, RaTME remained associated with higher ISR rates (4.5% versus 9.4%, P =0.022 after PSM; 4.9% versus 9.2, P =0.005 after IPTW). This association remained in multivariate analysis after adjusting for other confounding factors. RaTME was further associated with a higher CAA rate, longer operating time, and higher hospitalization expenses.

CONCLUSIONS

RaTME may facilitate ISR in middle and low rectal cancers, showing an independent association with a higher ISR incidence, with pathological outcomes and complications comparable to those of LaTME. However, it may also require a longer operating time and incur higher hospitalization expenses.

Transanal local excision versus intersphincteric resection for low rectal cancer with stage ypT0-1ycN0 after neoadjuvant chemoradiotherapy: an inverse probability weighting analysis for oncological and functional outcomes

OBJECTIVES

This study aimed to compare the efficacy of local excision (LE) and intersphincteric resection (ISR) in patients with locally advanced rectal cancer who achieved a significant or complete pathological response following neoadjuvant chemoradiotherapy.

METHODS

We performed a retrospective analysis of data from patients with stage ypT0-1ycN0 low rectal cancer after neoadjuvant chemoradiotherapy who underwent LE or ISR between June 2016 and June 2021. Baseline characteristics, short-term outcomes, long-term oncological outcomes, and functional outcomes, were compared between the two groups. To reduce the selection bias, inverse probability of treatment weighting (IPTW) was performed.

RESULTS

This study included 106 patients (LE group: n = 51, ISR group: n = 55). There were significant differences in baseline characteristics between the two groups (P < 0.05). After IPTW, there were almost no significant differences in baseline data between the two groups. The LE group showed less postoperative complications and better function outcomes compared to the ISR group. The LE group had significantly lower rates of complications (13.7% vs. 36.4%, P = 0.014). There were no significant differences between the two groups in terms of long-term oncological outcomes.

CONCLUSIONS

For patients with locally advanced low rectal cancer achieving significant or complete pathological response after neoadjuvant therapy, both LE and ISR present comparable oncological outcomes. Yet, LE seems to show more advantages in terms of postoperative complications and functional outcomes. These findings offer important insights for surgical decision-making, emphasizing the necessity to consider both oncological and functional outcomes in selecting the optimal surgical approach.