Transanal total mesorectal excision: technical aspects of approaching the mesorectal plane from below

Exfoliate cancer cell analysis in rectal cancer surgery: comparison of laparoscopic and transanal total mesorectal excision, a pilot study

PURPOSE

Minimally invasive surgery (MIS) is currently the standard treatment for rectal cancer. However, its limitations include complications and incomplete total mesorectal resection (TME) due to anatomical features and technical difficulties. Transanal TME (TaTME) has been practiced since 2010 to improve this, but there is a risk of local recurrence and intra-abdominal contamination. We aimed to analyze samples obtained through lavage to compare laparoscopic TME (LapTME) and TaTME.

METHODS

From June 2020 to January 2021, 20 patients with rectal cancer undergoing MIS were consecutively and prospectively recruited. Samples were collected at the start of surgery, immediately after TME, and after irrigation. The samples were analyzed for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) through a quantitative real-time polymerase chain reaction. The primary outcome was to compare the detected amounts of CEA and CK20 immediately after TME between the surgical methods.

RESULTS

Among the 20 patients, 13 underwent LapTME and 7 underwent TaTME. Tumor location was lower in TaTME (7.3 cm vs. 4.6 cm, P=0.012), and negative mesorectal fascia (MRF) was more in LapTME (76.9% vs. 28.6%, P=0.044). CEA and CK20 levels were high in 3 patients (42.9%) only in TaTME. There was 1 case of T4 with incomplete purse-string suture and 1 case of positive MRF with dissection failure. All patients were followed up for an average of 32.5 months without local recurrence.

CONCLUSION

CEA and CK20 levels were high only in TaTME and were related to tumor factors or intraoperative events. However, whether the detection amount is clinically related to local recurrence remains unclear.

Development of a formative feedback tool for transanal total mesorectal excision

INTRODUCTION

Transanal total mesorectal excision (TaTME) is a novel procedure in the treatment of rectal cancer. Current training models for TaTME suggest a period of proctored cases, but no structured feedback tool exists to guide operators during the learning phase. The objective of this study therefore was to develop a formative feedback tool for the critical steps of the transanal portion of TaTME.

METHODS

A two-round Delphi study by TaTME experts was conducted to determine the items to be included in the formative feedback tool. Participants rated each step from a prepared list using a Likert scale from 1 (Not relevant) to 5 (Very relevant) with the option to suggest additional steps. Responses to the first round were presented in the second round, where participants rated the revised list of steps. Consensus was defined as > 80% of participants rating the step as 4 or 5 (out of 5). Items were combined when appropriate to avoid redundancy. Rating anchors describing performance (on a 5-point scale) were then developed for each step. The final tool was recirculated and participants rated the finished product on its feasibility and usefulness.

RESULTS

Twenty-six TaTME experts were contacted for participation. Fifteen experts (58%) participated in the first round of the study, and eleven (42%) participated in the second round. The majority (14, 93%) had completed fellowship training in colorectal surgery. The first round of the Delphi study contained 34 items, and 32 items met inclusion criteria after the second round. Redundant items were combined into 15 items that comprised the final tool. Out of eight respondents to the feasibility survey, all believed the feedback tool enhances the feedback of learners and would use it for training purposes if available.

CONCLUSION

This work describes the development of a novel consensus-based formative feedback tool specific to TaTME.

Mesentery in Transanal TME

Oncological adequacy in rectal cancer surgery mandates not only a clear distal and circumferential resection margin but also resection of the entire ontogenetic mesorectal package. Incomplete removal of the mesentery is one of the commonest causes of local recurrences. The completeness of the resection is not only determined by tumor and patient related factors but also by the patient-tailored treatment selected by the multidisciplinary team. This is performed in the context of the technical ability and experience of the surgeon to ensure an optimal total mesorectal excision (TME). In TME, popularized by Professor Heald in the early 1980s as a sharp dissection through the avascular embryologic plane, the midline pedicle of tumor and mesorectum is separated from the surrounding, mostly paired structures of the retroperitoneum. Although TME significantly improved the oncological and functional results of rectal cancer surgery, the difficulty of the procedure is still mainly dependent on and determined by the dissection of the most distal part of the rectum and mesorectum. To overcome some of the limitations of working in the narrowest part of the pelvis, robotic and transanal surgery have been shown to improve the access and quality of resection in minimally invasive techniques. Whatever technique is chosen to perform a TME, embryologically derived planes and anatomical points of reference should be identified to guide the surgery. Standardization of the chosen technique, widespread education, and training of surgeons, as well as caseloads per surgeon, are important factors to optimize outcomes. In this article, we discuss the introduction of transanal TME, with emphasis on the mesentery, relevant anatomy, standard procedural steps, and importance of a training pathway.

Development and evaluation of a virtual knowledge assessment tool for transanal total mesorectal excision

BACKGROUND

Transanal total mesorectal excision (TATME) is difficult to learn and can result in serious complications. Current paradigms for assessing performance and competency may be insufficient. This study aims to develop and provide preliminary validity evidence for a TATME virtual assessment tool (TATME-VAT) to assess the cognitive skills necessary to safely complete TATME dissection.

METHODS

Participants from North America, Europe, Japan and China completed the test via an interactive online platform between 11/2019 and 05/2020. They were grouped into expert, experienced and novice surgeons depending on the number of independently performed TATMEs. TATME-VAT is a 24-item web-based assessment evaluating advanced cognitive skills, designed according to a blueprint from consensus guidelines. Eight items were multiple choice questions. Sixteen items required making annotations on still frames of TATME videos (VCT) and were scored using a validated algorithm derived from experts' responses. Annotation (range 0-100), multiple choice (range 0-100), and overall scores (sum of annotation and multiple-choice scores, normalized to μ = 50 and σ = 10) were reported.

RESULTS

There were significant differences between the expert, experienced, and novice groups for the annotation (p < 0.001), multiple-choice (p < 0.001), and overall scores (p < 0.001). The annotation (p = 0.439) and overall (p = 0.152) scores were similar between the experienced and novice groups. Annotation scores were higher in participants with 51 or more vs. 30-50 vs. less than 30 cases. Scores were also lower in users with a self-reported recent complication vs. those without.

CONCLUSIONS

This study describes the development of an interactive video-based virtual assessment tool for TATME dissection and provides initial validity evidence for its use.

Local Recurrence After Transanal Total Mesorectal Excision for Rectal Cancer: A Multicenter Cohort Study

OBJECTIVE

This study aimed to determine local recurrence (LR) rate and pattern after transanal total mesorectal excision (TaTME) for rectal cancer.

BACKGROUND

TaTME for mid- and low rectal cancer has known a rapid and worldwide adoption. Recently, concerns have been raised on the oncological safety in light of reported high LR rates with a multifocal pattern.

METHODS

This was a multicenter observational cohort study in 6 tertiary referral centers. All consecutive TaTME cases for primary rectal adenocarcinoma from the first TaTME case in every center until December 2018 were included for analysis. Patients with benign tumors, malignancies other than adenocarcinoma and recurrent rectal cancer, as well as exenterative procedures, were excluded. The primary endpoint was 2-year LR rate. Secondary endpoints included patterns and treatment of LR and histopathological characteristics of the primary surgery.

RESULTS

A total of 767 patients were identified and eligible for analysis. Resection margins were involved in 8% and optimal pathological outcome (clear margins, (nearly) complete specimen, no perforation) was achieved in 86% of patients. After a median follow-up of 25.5 months, 24 patients developed LR, with an actuarial cumulative 2-year LR rate of 3% (95% CI 2-5). In none of the patients, a multifocal pattern of LR was observed. Thirteen patients had isolated LR (without systemic disease) and 10/13 could be managed by salvage surgery of whom 8 were disease-free at the end of follow-up.

CONCLUSIONS AND RELEVANCE

This study shows good loco regional control after TaTME in selected cases from tertiary referral centers and does not indicate an inherent oncological risk of the surgical technique.

Education and Training in Transanal Endoscopic Surgery and Transanal Total Mesorectal Excision

There is a paradigm shift in surgical training, and new tool and technology are being used to facilitate mastery of the content and technical skills. The transanal procedures for rectal cancer-transanal endoscopic surgery (TES) and transanal total mesorectal excision (TaTME)-have a distinct learning curve for competence in the procedures, and require special training for familiarity with the "bottom-up" anatomy, procedural risks, and managing complex cases. These procedures have been models for structured education and training, using multimodal tools, to ensure safe implementation of TES and TaTME into clinical practice. The goal of this work was to review the current state of surgical education, the introduction and learning curve of the TES and TaTME procedures, and the established and future models for education of the transanal procedures for rectal cancer.

Association of Transanal Total Mesorectal Excision With Local Recurrence of Rectal Cancer

IMPORTANCE

Proponents of novel transanal total mesorectal excision (TME) suggest the procedure overcomes the technical and oncologic challenges of conventional approaches for treating rectal cancer. Recently, however, there has been controversy regarding the oncologic safety of the procedure.

OBJECTIVE

To assess the association of transanal TME with the incidence of local recurrence (LR) of cancer and the probability of remaining free of LR during follow-up.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study used data from 8 high-volume rectal cancer academic institutions from across Canada on all consecutive patients with primary rectal cancer treated by transanal TME at the participating centers. The study was conducted between January 2014 and December 2018, and data were analyzed from April 1, 2020, to September 15, 2020.

EXPOSURE

Transanal TME.

MAIN OUTCOMES AND MEASURES

The incidence of LR was reported as a direct measure of quality of resection. The cumulative probability of LR- and systemic recurrence (SR)-free survival at 36 months was estimated. Local recurrence and SR were defined as radiologic or endoscopic evidence of 1 or more new lesions in or outside the pelvis, respectively, documented during surveillance after the removal of the primary tumor.

RESULTS

Of 608 total patients included in the analysis, 423 (69.6%) were male; the median age was 63 years (interquartile range [IQR], 54-70 years). Local recurrence was identified in 22 patients (3.6%) after a median follow-up of 27 months (IQR, 18-38 months). The median time to LR was 13 months (IQR, 9-19 months). Sixteen of the 22 patients with LR (72.7%) were male, 14 (63.6%) received neoadjuvant chemoradiation, and 12 (54.5%) had American Joint Committee on Cancer stage III disease. Of those with LR, 16 (72.7%) had a negative circumferential radial margin and 20 (90.9%) had a negative distal resection margin, 2 (9.1%) experienced conversion to open surgery, and 15 (68.2%) also developed SR. The probability of LR-free survival at 36 months was 96% (95% CI, 94%-98%). According to the Cox proportional hazards regression model, the hazard ratio of LR was estimated to be 4.2 (95% CI, 2.9-6.2) times higher among patients with a positive circumferential radial margin than among those with a negative circumferential radial margin.

CONCLUSIONS AND RELEVANCE

In this cohort study, transanal TME performed by experienced surgeons was associated with an incidence of LR and SR that is in line with the published literature on open and laparoscopic TME, suggesting that transanal TME may be an acceptable approach for management of rectal cancer.

Computer-assisted real-time automatic prostate segmentation during TaTME: a single-center feasibility study

BACKGROUND

Urethral injuries (UIs) are significant complications pertaining to transanal total mesorectal excision (TaTME). It is important for surgeons to identify the prostate during TaTME to prevent UI occurrence; intraoperative image navigation could be considered useful in this regard. This study aims at developing a deep learning model for real-time automatic prostate segmentation based on intraoperative video during TaTME. The proposed model's performance has been evaluated.

METHODS

This was a single-institution retrospective feasibility study. Semantic segmentation of the prostate area was performed using a convolutional neural network (CNN)-based approach. DeepLab v3 plus was utilized as the CNN model for the semantic segmentation task. The Dice coefficient (DC), which is calculated based on the overlapping area between the ground truth and predicted area, was utilized as an evaluation metric for the proposed model.

RESULTS

Five hundred prostate images were randomly extracted from 17 TaTME videos, and the prostate area was manually annotated on each image. Fivefold cross-validation tests were performed, and as observed, the average DC value equaled 0.71 ± 0.04, the maximum value being 0.77. Additionally, the model operated at 11 fps, which provides acceptable real-time performance.

CONCLUSIONS

To the best of the authors' knowledge, this is the first effort toward realization of computer-assisted TaTME, and results obtained in this study suggest that the proposed deep learning model can be utilized for real-time automatic prostate segmentation. In future endeavors, the accuracy and performance of the proposed model will be improved to enable its use in practical applications, and its capability to reduce UI risks during TaTME will be verified.

Total Mesorectal Excision Technique-Past, Present, and Future

While the treatment of rectal cancer is multimodal, above all, a proper oncological resection is critical. The surgical management of rectal cancer has substantially evolved over the past 100 years, and continues to progress as we seek the best treatment. Rectal cancer was historically an unsurvivable disease, with poor understanding of the embryological planes, lymphatic drainage, and lack of standardized technique. Major improvements in recurrence, survival, and quality of life have resulted from advances in preoperative staging, pathologic assessment, the development and timing of multimodal therapies, and surgical technique. The most significant contribution in advancing rectal cancer care may be the standardization and widespread implementation of total mesorectal excision (TME). The TME, popularized by Professor Heald in the early 1980s as a sharp, meticulous dissection of the tumor and mesorectum with all associated lymph nodes through the avascular embryologic plane, has shown universal reproducible reductions in local recurrence and improvement in disease-free and overall survival. Widespread education and training of surgeons worldwide in the TME have significantly impact outcomes for rectal cancer surgery, and the procedure has become the gold standard for curative resection of rectal cancer. In this article, we discuss the evolution of the standard abdominal approach to the TME, with emphasis on the history, relevant anatomy, standard procedure steps, oncologic outcomes, and technical evolution.

Treatment of Rectal Cancer in Older Adults

PURPOSE OF REVIEW

Rectal cancer is predominantly a disease of older adults but current guidelines do not incorporate the associated specific challenges leading to wide variation in the delivery of cancer care to this subset of population. Here, we will review the current data available regarding the management of rectal cancer in older adults.

RECENT FINDINGS

The greatest challenge arises in the management of stage II/III disease as it involves tri-modality treatment that can be harder to tolerate by frail older patients. Response to neoadjuvant treatment is being used as a new marker to tailor further therapy and possibly avoid surgery. Oxaliplatin can be omitted from the adjuvant treatment without compromising outcomes. Physicians should perform geriatric assessment utilizing many validated tools available to help predict treatment tolerability and outcomes in older adults that can help personalize subsequent management. Most older adults can undergo standard therapy for stages I, II, or III rectal cancer with curative intent. Increasing evidence suggests that patients with a clinical complete response to neoadjuvant treatment may be observed closely with the possibility of avoiding surgery. Studies are evaluating alternate systemic treatments for advanced metastatic disease with the hope of maintaining quality of life without compromising cancer outcomes.

Transanal total mesorectal excision (taTME) in a single-surgeon setting: refinements of the technique during the learning phase

BACKGROUND

Transanal total mesorectal excision (taTME) is a safe and effective technique. We have progressively developed a systematic approach in the single-surgeon setting. The aim of this study was to compare our early vs late single-surgeon taTME experience as well as present the technical and logistical modifications that were crucial to achieve successful implementation of a taTME program.

METHODS

Review of prospectively collected data on 27 patients who had taTME in June 2015-September 2016 (early cohort) was included and compared with 43 patients who underwent taTME in October 2016-September 2017 (late cohort). Procedures were performed by a single-surgeon team at Health Sciences North (Sudbury, Ontario, Canada). Inclusion criteria were T1-3 or downstaged T4 mid- and low-rectal lesions. Cases of non-neoplastic disease were excluded. Outcomes assessed included mesorectal integrity, margin status, operative time, complications, morbidity, length of stay and 30-day readmission.

RESULTS

A total of 70 cases were included. Patients were divided into early (27 patients, 14 males; mean age 60.74 ± 9.77 years) and late (43 patients, 29 males; mean age 63.48 ± 10.85 years) cohorts. During the early phase, procedural modifications including regular takedown of the splenic flexure, intra-corporeal division of the mesentery, liberal use of a Pfannenstiel incision for extraction, abundant washing of the surgical field and regular use of the ICG technology were progressively introduced. There was no mortality nor statistically significant difference between the early and late cohort in terms of morbidity (33.3 vs 39.4% p = 0.727), anastomotic leak (14.8 vs 4.6% p = 0.19), operating time (5.05 ± 1.26 vs 4.96 ± 1.14 h p = 0.755), length of stay (4.0 ± 2.54 vs 4.81 ± 3.63 days p = 0.394) and CRM negative margin (96.3 vs. 97.7% p = 0.999), and no incomplete specimens were obtained on either cohort.

CONCLUSIONS

This study confirms the safety and effectiveness of single-surgeon implementation of taTME technique. Technical challenges experienced in this setting were not obstacles for further refinement and to establish a tendency towards better outcomes. Overcoming technical challenges is possible, familiarity with taTME is slow yet progressive, and improvement tends to occur with experience.

Cognitive skills training in digital era: A paradigm shift in surgical education using the TaTME model

Surgical competence is a complex, multifactorial process, requiring ample time and training. Optimal training is based on acquiring knowledge and psychomotor and cognitive skills. Practicing surgical skills is one of the most crucial tasks for both the novice surgeon learning new procedures and surgeons already in practice learning new techniques. Focus is placed on teaching traditional technical skills, but the importance of cognitive skills cannot be underestimated. Cognitive skills allow recognizing environmental cues to improve technical performance including situational awareness, mental readiness, risk assessment, anticipating problems, decision-making, adaptation, and flexibility, and may also accelerate the trainee's understanding of a procedure, formalize the steps being practiced, and reduce the overall training time to become technically proficient. The introduction and implementation of the transanal total mesorectal excision (TaTME) into practice may be the best demonstration of this new model of teaching and training, including pre-training, course attendance, and post-course guidance on technical and cognitive skills. To date, the TaTME framework has been the ideal model for structured training to ensure safe implementation. Further development of metrics to grade successful learning and assessment of long term outcomes with the new pathway will confirm the success of this training model.

Operative vectors, anatomic distortion, fluid dynamics and the inherent effects of pneumatic insufflation encountered during transanal total mesorectal excision

BACKGROUND

Transanal total mesorectal excision (taTME) is an altogether different approach to rectal cancer surgery, and the effects of carbon dioxide (CO₂) on this dissection remain poorly described.

METHODS

This article critically examines the effect of carbon dioxide insufflation and the workspace it creates during the process of taTME. The unique aspects of insulation with this approach are governed by the laws of physics, especially the principles of fluid dynamics, an area that remains poorly described for laparoscopy and not at all described for taTME.

RESULTS

A summary of established factors which affect the operative field of the taTME surgeon is delineated and further explored. In addition, new concepts regarding gas delivery, such as insufflation vectors, anatomic distortion, hyper-dissection, and workspace volume rate of change as a function of taTME dissection time, are addressed. Collectively, these factors pose important challenges which increase case complexity and are thus essential for taTME trainers and trainees alike to understand.

CONCLUSIONS

Although an invisible gas, CO₂ insufflation with taTME produces markedly visible effects which are imposed upon the operative field. This can result in anatomic distortion and misperception of operative planes. Thus, practicing taTME surgeons should be cognizant of these effects.

New Strategies in Rectal Cancer

In recent years, our understanding of rectal cancer has improved, including how locally advanced disease responds to chemotherapy and radiation. This has led to new innovations and advances in the treatment of rectal cancer, which includes organ-preserving strategies for responsive disease, and minimally invasive approaces for the performance of total mesorectal excision/protectomyh for persistently advanced disease. This article discusses new strategies for rectal cancer therapy, including Watch and Wait, local excision, minimally invasive proctectomy, and transanal total mesorectal excision particularly in the setting of preoperative multimodality treatment.

Surgery beyond the visible light spectrum: theoretical and applied methods for localization of the male urethra during transanal total mesorectal excision

The risk of urethral injury during transanal total mesorectal excision (taTME) is delineated, and potential risk factors for iatrogenic transection are reviewed. A variety of applied and theoretical techniques can be used by surgeons to diminish the risk of injury in males undergoing this operation. Many of the approaches utilize non-optic media and wavelengths beyond the visible light spectrum which can enhance the surgeon's frame of reference. The aim of the present study was to assess the techniques and theoretical approaches to urethral localization during taTME. Future directions in surgical imaging are also discussed, including the use of organic dyes, quantum dots, and carbon nanotubes; collectively, technology that could someday provide surgeons with an ability to identify anatomic structures prone to injury.