Endoscopic submucosal dissection (ESD) and transanal endoscopic submucosal dissection (TES) are widely employed surgical techniques. However, the comparative efficacy and safety of both remain inconclusive.

To comprehensively analyze and discern differences in surgical outcomes between ESD and TES.

We conducted a systematic search of the electronic databases PubMed, Embase, Cochrane Central Register of Controlled Trials, Scopus, and CINAHL from inception till August 2023. We analyzed outcomes including recurrence rate, en bloc resection, R0 resection rate, perforation rate, procedure length, and hospital stay length applying a random-effects inverse-variance model. We assessed publication bias by conducting an Egger’s regression test and sensitivity analyses.

We pooled data from 11 studies involving 1013 participants. We found similar recurrence rates, with a pooled odds ratio of 0.545 (95%CI: 0.176-1.687). En bloc resection, R0 resection, and perforation rate values were also similar for both ESD and TES. The pooled analysis for procedure length indicated a mean difference of -4.19 min (95%CI: -22.73 to 14.35), and the hospital stay was on average shorter for ESDs by about 0.789 days (95%CI: -1.671 to 0.093).

Both ESD and TES displayed similar efficacy and safety profiles across multiple outcomes. Our findings show that individualized patient and surgeon preferences, alongside specific clinical contexts, can be considered when selecting between these two techniques.

The realm of colorectal surgery has witnessed transformative advancements over the past few decades, especially in the domain of minimally invasive procedures[1]. These innovations reflect the fusion of technology with the surgical craft and mark the relentless pursuit to achieve optimal outcomes with minimal surgical intrusion[2]. In this context, the most suitable approach to resect rectal tumors needs to be identified. Two leading techniques have emerged at the forefront: Endoscopic submucosal dissection (ESD) and transanal endoscopic surgery (TES)[3]. However, their relative merits, applications, and outcomes demand a meticulous evaluation. With this systematic review and meta-analysis we compare the two techniques, shedding light on their efficacies and potential roles in modern colorectal surgical practice.

Rectal tumors, whether benign or malignant, pose considerable management challenges due to their anatomical location and the complications and morbidity associated with their surgical resection[4]. Traditional surgical techniques, while effective, often require extensive tissue dissection, resulting in prolonged recovery, potential for morbidity, and significant bowel function alterations[5]. By contrast, minimally invasive techniques offer patients a combination of effective tumor resection and quality of life preservation[6].

The ESD approach originated in East Asia and has become a promising technique for the removal of early neoplasms of the gastrointestinal tract[7]. By allowing en bloc resection of lesions irrespective of their size, ESDs aim to achieve clear histological margins to enhance the accuracy of histopathological assessments and reduce recurrence rates[8]. Moreover, the endoluminal procedure significantly reduces the potential for abdominal or pelvic surgical complications[9]. However, the steep learning curve associated with ESDs, especially when applied to the rectum, and its intricate procedural demands have led practitioners to question its universal applicability and efficacy[10].

The TES, evolved from the earlier transanal endoscopic microsurgery, presents a more familiar technique for colorectal surgeons[11]. By offering a direct, magnified view of the rectal lumen and leveraging well-understood principles of surgical dissection, TES seems to combine the advantages of endoscopic and open surgical techniques. The potential for achieving R0 resection, coupled with the promise of reduced post-operative morbidity, positions TES as a compelling alternative to traditional and other endoscopic techniques[12]. However, like all surgical techniques, TES is not devoid of challenges. The technical demands of the procedure, potential complications, and the need for specialized equipment have been cited as limiting factors[11]. Moreover, while TES has demonstrated promise in several studies, its comparative efficacy vis-à-vis ESD, especially in terms of oncological outcomes, remains a point of contention[3].

Thus, comparing the ESD and TES techniques for rectal tumor resections is important. With this systematic review and meta-analysis, we seek to synthesize the collective wisdom of the global surgical community, to derive evidence-based conclusions that may potentially guide clinical decision-making. By analyzing outcomes, complications, learning curves, and patient-centric parameters, we hope to present a comprehensive analysis that stands up to the rigorous standards of evidence-based medicine.

As the realm of colorectal surgery continues to evolve, driven by technology and a deeper understanding of disease processes, the surgical community needs to continually evaluate, adapt, and optimize techniques. It is with this goal of continual refinement and progress that we performed this review on two leading techniques for rectal tumor resection.

We adhered stringently to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines[13] to conduct this systematic review and meta-analysis. The protocol was registered at PROSPERO, CRD42023463730.

In this comprehensive meta-analysis, we sought to compare the surgical ESD and TES techniques in terms of their relative efficacies and outcomes. We assessed a range of outcomes including recurrence rates, en bloc and R0 resection rates, perforation rates, and procedure and hospital stay lengths. We chose these variables to help us evaluate the effectiveness and feasibility of the two approaches.

Our findings on recurrence rate are important, because recurrence remains a post-operative challenge in surgical oncology. The pooled odds ratio of 0.545 with a 95%CI ranging from 0.176 to 1.687 suggests that both techniques have similar recurrence rates, and the associated Z-value and P values confirm this. This finding is crucial for clinicians weighing the long-term implications of either surgical method. However, we also found considerable heterogeneity among the studies involved. An I² statistic of 55.2% underscores a moderate-to-high variance in outcomes, indicating potential differences in study designs, patient populations, or surgical technique implementation. Thus, standardized multicentric studies are needed to generate a clear picture.

ESD offers direct visualization with a minimal invasion of the submucosal layer. The endoscopic technique is particularly useful in instances where tumors are located in difficult-to-access areas or when they are large and display a high risk of malignancy[3]. By contrast, TES is often preferred for localized tumors, especially when invasion beyond the mucosa is suspected[11]. Understanding the context in which each technique excels is critical for making informed surgical decisions.

Resection methods—whether en bloc or R0—affect the prognosis, recurrence, and overall patient morbidity differently[27]. Our pooled analyses in these domains yielded non-significant differences between the two techniques. This apparent equivalency between ESD and TES should be interpreted with caution due to the substantial heterogeneity in the en bloc resection data (I² = 76.2%). Considering the broader context of surgical goals is important; while complete tumor removal is the principal aim, the assurance that a procedure will accomplish this without increasing the recurrence risk is equally essential. ESDs are used primarily for precise en bloc tumor removals, especially in patients with tumors that are large or are spread superficially. By contrast, TES provides a direct and effective approach for tumors in the lower rectum. These technical differences must be weighed in when assessing the equivalent outcomes we are presenting.

Perforation, albeit a rare complication, is associated with substantial morbidity and potential mortality. Our findings suggesting similarly low perforation rates for both groups is reassuring. With an odds ratio of 1.543, both methods appear to offer comparable safety profiles. The relatively low heterogeneity (I² of 18.7%) further strengthens our confidence in these results.

Efficiency in surgical procedures, in terms of duration, impacts hospital resource allocation and can have implications on patient outcomes. Our meta-analysis indicates a non-significant difference in procedure length between ESD and TES. However, the substantial heterogeneity we observed (I² = 87.3%) highlights the need for standardization in procedural techniques, patient selection, and post-operative care protocols. The steps in the ESD and TES procedures reveal clues behind the similar procedure lengths. While ESD demands careful dissection of the submucosal layer, especially in patients with large tumors; TES requires precise localization and access through the transanal approach. Such technical nuances, coupled with surgeon expertise, play a decisive role in procedure length.

An important aspect to consider in comparing ESD and TES is the difference in anaesthesia methods used for these procedures. ESD often requires conscious sedation or general anaesthesia, depending on the size and location of the tumour, as well as patient factors. This type of anaesthesia allows for patient comfort while maintaining a degree of responsiveness. In contrast, TES typically necessitates general anaesthesia due to its more invasive nature and the potential for discomfort in the transanal approach. The choice of anaesthesia can impact patient recovery, procedure duration, and overall patient experience. This distinction is crucial for a comprehensive comparison of ESD and TES, as it not only influences the procedural approach but may also have implications for post-operative recovery and patient satisfaction.

The hospital stay length, which directly impacts healthcare costs and patient convenience, showed a trend towards a shorter stay for ESD. Although this difference did not reach statistical significance, the trend can have substantial implications for high-throughput centers. The explanation for this difference in hospital stay lengths may be due to ESD’s minimal invasiveness. By contrast, TES, may involve more extensive tissue manipulation, potentially necessitating longer post-operative recovery.

Other meta-analyses have compared outcomes of ESD and TES[3,28]. However, the most notable of those meta-analyses, with similar outcome findings to ours incorporated only half the number of studies we scrutinized in here[3,28]. Our expanded population numbers broaden the empirical base and potentially incorporate a wider range of specific populations, surgical techniques, and clinical settings. We believe the large population in our analysis makes our conclusions more generalizable and robust.

In any case, the parallels between our findings and those of previous research highlight the consistency across analyses. However, with our analysis of a large population, we also uncovered heterogeneity among the studies.

In pondering the similarities in the outcomes of these different techniques, we highlight a few factors. First, advances in both the ESD and TES techniques over the years may have converged their efficacy profiles. Surgeons may have optimized the techniques, leading to similar outcomes across both modalities[29]. Second, the standard of care in post-operative settings has evolved to minimize complications and improve recovery, irrespective of the surgical method applied to individual cases[30]. Finally, patient selection, a pivotal aspect of any surgical intervention, may have been refined with accumulating clinical experience, ensuring that the most appropriate individual patient profiles have been applied[31].

Our rigorous approach to assessing publication bias, involving the Egger’s regression test, showed no significant evidence of such bias. This enhances the validity of our findings. Moreover, our systematic sensitivity analyses across all domains underscore the robustness of our conclusions, with no single study unduly influencing the collective results. This is paramount in a meta-analytic approach, ensuring that our findings are not skewed by outlier data or disproportionately influential studies.

When choosing a technique between ESD and TES, several factors need to be considered: Tumor location, size, and depth of invasion are pivotal. For instance, superficial tumors, especially those in challenging locations, may be better suited for ESD, given its fine-tuned submucosal access. By contrast, TES might be the method of choice for tumors that are deeper or situated in the lower rectum. Beyond tumor characteristics, surgeon expertise and familiarity with each procedure, as well as available institutional resources, also have a decisive role.

Patient-specific variables, such as age, comorbidities, and prior surgical history need to be taken into consideration because they can influence post-operative recovery and the risk of complications. The choice between ESD and TES should be individualized after consideration of the entire clinical picture.

While our analysis is robust and comprehensive, it has its limitations. The possibility of selection bias and a lack of RCTs are our primary concerns. The heterogeneity we observed across outcomes warrants attention. Differences in patient populations, surgical expertise, hospital resources, and post-operative care can all contribute to this variance. However, future studies should strive for standardized methodologies and clear reporting of outcomes to minimize this heterogeneity.

Our meta-analysis offers a comprehensive comparison between ESD and TES across multiple critical domains. The lack of significant differences in recurrence, resection rates, perforation rates, and procedure lengths suggests that both surgical techniques have their merits and can be chosen based on individual patient needs, surgeon expertise, and institutional resources. The potential reduction in hospital stays with ESD, though not statistically significant, may offer strategic advantages in specific healthcare settings. We hope that this synthesis will aid in clinical decision-making, and we underscore the need for further research with standardized methodologies.