Local excision in rectal cancer: When and for whom?

Abstract

Local excision (LE) is an effective treatment option for rectal cancer that shows significant regression following neoadjuvant chemoradiotherapy. Compared to traditional total mesorectal excision (TME), LE can achieve comparable oncological outcomes while preserving function and improving quality of life (QoL). The indications for LE have been gradually expanded, but there are uncertainties regarding postoperative oncological results. Long-term follow-up prospective randomized controlled trials comparing TME and LE in terms of both oncological outcomes and QoL could help reduce uncertainties between these two approaches and contribute to the development of evidence-based guidelines for rectal cancer treatment.

Key Words: Rectal cancer; Low anterior resection syndrome; Local excision; Quality of life; Total mesorectal excision; Transanal minimally invasive surgery; Neoadjuvant chemoradiotherapy; Transanal endoscopic microsurgery

Core Tip: Local excision (LE) may be considered for rectal cancer patients who exhibit significant tumor regression following neoadjuvant chemoradiotherapy. LE, which includes transanal endoscopic microsurgery and transanal minimally invasive surgery, is a feasible and effective surgical method that can achieve oncological results similar to those of total mesorectal excision but causes relatively less functional loss, shorter hospital stays, less blood loss, and improved quality of life. It is important to carefully select suitable patients for LE, but its indications are gradually expanding with studies in the literature. However, inadequate guidelines, lack of information about postoperative oncological outcomes and appropriate patient selection, and preoperative staging play an important role in creating a treatment plan for rectal cancer.

TO THE EDITOR

Total mesorectal excision (TME) remains the standard surgical approach for patients with locally advanced rectal cancer following neoadjuvant chemoradiotherapy (nCRT)[1]. While TME improves oncologic outcomes, it is associated with substantial impairment in postoperative quality of life (QoL) due to complications such as urinary, sexual, and defecatory dysfunction, and particularly low anterior resection syndrome (LARS)[2]. Moreover, the low anatomical location of most rectal cancers often necessitates temporary or permanent stoma formation, further affecting long-term patient well-being[3,4].

Local excision (LE), especially when performed with transanal endoscopic techniques, has emerged as a less invasive, organ-preserving alternative for select cases, particularly in early-stage rectal cancer (T1N0M0) without adverse pathological features[5]. Techniques such as transanal endoscopic microsurgery (TEM), transanal minimally invasive surgery (TAMIS), and conventional transanal excision (TAE) offer favorable oncologic and functional outcomes in selected patients[6,7]. TEM provides enhanced visualization and precise specimen retrieval, whereas TAMIS allows the use of standard laparoscopic tools at a lower cost[8]. Comparative analyses indicate that LE can achieve local recurrence rates of 6%-8% and 5-year survival rates of 85%-90%, comparable to those of TME in ypT0-1 tumors[9,10].

A retrospective study by Chen et al[11] demonstrated a 92% organ preservation rate in patients who underwent LE after nCRT. However, critical limitations should be considered when interpreting these results. The study involved a selected cohort with favorable tumor characteristics, potentially overestimating LE efficacy. Furthermore, the absence of a control group undergoing standard TME restricts the validity of comparative conclusions. Long-term functional and QoL outcomes were underreported, limiting insight into broader patient impacts. Additionally, the inclusion of heterogeneous patient subgroups, including those with distant metastases (cM1) and varying clinical T stages (cT2-cT4), complicates the interpretation of LE’s true oncologic safety. In contrast, Jin et al[12] excluded cM1 patients in their comparative analysis of LE and TME, allowing for a more homogenous and interpretable study population.

A significant limitation across current studies is the lack of standardized methods for evaluating response to nCRT. Conventional modalities—digital rectal examination, magnetic resonance imaging (MRI), and endoscopy—demonstrate only moderate agreement[13]. Additionally, high costs associated with LE techniques, particularly TEM systems ($50000-$100000), may pose barriers to widespread adoption, especially in low-resource settings[14].

To improve the evidence base for LE after nCRT, future research should incorporate clear inclusion criteria, such as clinical stage ycT0-1N0 confirmed via high-resolution MRI and endoscopic assessment, alongside biopsy evidence of > 50% fibrosis[15-17]. Anatomically, optimal candidates should present with tumors ≤ 3 cm in diameter, ≥ 1 cm from the anal verge, and involving < 40% of the rectal circumference. Biologically, microsatellite stability or proficient mismatch repair status should be prioritized, given the elevated risk of incomplete resection in microsatellite instability-high tumors[16,18].

Innovative tools such as artificial intelligence-enhanced MRI and circulating tumor DNA assays offer potential for more accurate, objective patient selection[19,20]. These technologies could refine LE candidacy and enable broader clinical application. Furthermore, hybrid approaches—using LE as “completion surgery” for near-complete responders—may spare 60%-70% of patients from radical procedures, while reserving salvage TME for high-risk pathology (e.g., ypT2, close margins)[21].

In-depth comparisons between LE modalities (TEM vs TAMIS vs TME) and cost-utility analyses, particularly those considering stoma-related quality-of-life metrics, are essential. Additionally, standardized outcome assessments using validated instruments, such as the LARS score or the Memorial Sloan Kettering Cancer Center Bowel Function Instrument questionnaire, are urgently needed to evaluate functional recovery and guide personalized surgical decision-making[22,23].

In conclusion, Chen et al[11] have contributed valuable data supporting the feasibility of LE following nCRT in rectal cancer. However, their findings should be interpreted in the context of methodological limitations, heterogeneous patient selection, and a lack of long-term functional outcomes. Future prospective studies with rigorous design, standardized evaluation tools, and cost-effectiveness analyses are imperative to validate LE as a safe and effective organ-preserving strategy in rectal cancer management.