Comment on “Intersphincteric complex a potential metastasis niche in ultralow rectal cancer and prognostic significance of its complete excision following intersphincteric resection – a prospective cohort study”

Dear Editor, We read with great interest the article entitled “Intersphincteric complex a potential metastasis niche in ultralow rectal cancer and prognostic signiffcance of its complete excision following intersphincteric resection—a prospective cohort study”[1], which has been published in the International Journal of Surgery. The introduction of intersphincteric resection (ISR) surgery provides new hope for patients with ultra-low rectal cancer, as it avoids the need for a permanent stoma and markedly enhances their quality of life. The classification of ISR was based on the range of resection of the internal anal sphincter (IAS), categorizing it into partial ISR, subtotal ISR, and total ISR[2]. In this study, the authors introduced the concept of the intersphincteric complex (ISC), defining it as an integrated anatomical structure within the intersphincteric space (ISS), composed of the conjoint longitudinal muscle (CLM), as well as associated nerves, blood vessels, lymphatic vessels, and adipose tissue. Based on the extent of intersphincteric complex excision, ISR was categorized into complete (CISCE), incomplete (ICISCE), and none (NISCE) groups. We commend the authors for proposing this innovative classification framework. However, there are several aspects of the study that warrant further clarification and discussion. We state that the manuscript was developed following the TITAN Guidelines 2025[3]for the declaration and use of artificial intelligence in scholarly publishing. No AI tools were employed in the conception, design, analysis, interpretation, or writing of this work. First, the intersphincteric space (ISS) is a relatively narrow anatomical region, and the thickness of the ISC may vary according to body mass index (BMI). In individuals with obesity, the ISC tends to be thicker, whereas in lean individuals, it may be thinner or even barely discernible. Given these anatomical variations, it is reasonable to consider whether a newly proposed classification system based on the extent of ISC resection should include BMI as a relevant factor. Second, the assessment of anal function is a crucial element in evaluating outcomes following ISR[4]. In this study, although the authors reported no significant differences in postoperative Wexner scores between groups, they did not consider the preoperative anal functional status across groups. Considering that the average age of the patients was close to 60 years, evaluating baseline anal function—particularly in elderly patients—is essential to prevent potential bias in interpreting postoperative functional outcomes. Therefore, we recommend that future studies incorporate a comprehensive preoperative assessment of anal functional status. Third, as stated by the authors, preserving the sphincter and sphincter nerves can significantly enhance the recovery of anal function after ISR[5]. In the CISCE group, where the ISC was completely removed, this procedure may negatively affect postoperative anal functional recovery. Therefore, it is worth considering whether CISCE can be avoided in patients with early-stage tumors without compromising oncological outcomes. Although the authors compared tumor prognosis across T and N stage subgroups, they did not conduct subgroup analyses based on the TNM staging system, which would more accurately reflect clinical decision-making. We hope that future studies by the authors will incorporate this perspective in order to identify the optimal patient population for CISCE. Fourth, it is perplexing that the authors note in the article that patients with ISC metastatic cancer cell clusters are more likely to exhibit poor differentiation (P = 0.018), advanced T stage (P = 0.015), and lymph node metastasis (P = 0.025). However, as shown in Figure I in the original article, the number of lymph node metastases in the metastatic cancer cell clusters-positive group appears to be significantly lower than that in the metastatic cancer cell clusters-negative group. The authors are therefore encouraged to clarify this apparent discrepancy. In conclusion, we would like to express our gratitude for this insightful article, which has enhanced our understanding of the structure and function of the ISC. The authors, novel classification of the ISR is particularly noteworthy; however, we encourage future research from the authors to incorporate the aforementioned aspects in order to more comprehensively establish the scientific validity and practical applicability of this classification system.