Current guidelines recommend STER and thoracic surgery as treatment options for esophageal SELs, with STER specifically advised for SELs measuring ≤ 3.5 cm [4, 10]. However, the safety and efficacy of STER for larger SELs remain uncertain. Our study, which compared the efficacy and safety profiles of STER for SELs of different sizes, has demonstrated for the first time that STER was both safe and effective for esophageal SELs with a maximum diameter < 5.0 cm. For SELs ≥ 5.0 cm, while STER remained effective, it was associated with more AEs, a higher number of difficult procedures, and higher possibilities of ICU transfers. Therefore, when treating SELs ≥ 5.0 cm, a more cautious evaluation and preparation were necessary.

The decision to use STER is primarily influenced by the size of the SELs, limited by the narrow dimensions of the submucosal tunnel and esophageal space [15]. Studies have confirmed the safety and effectiveness of STER for SELs < 3.0 cm. Xu et al. treated 15 upper gastrointestinal SELs with STER, including 9 esophageal SELs, achieving a 100.0% complete resection and retrieval rate. Complications included 1 (6.7%) case of pneumothorax requiring drainage and 1 (6.7%) case of pneumoperitoneum requiring abdominal decompression, with no recurrences or metastases found [7]. Similarly, Inoue et al. performed STER on 9 patients with SELs [8]. 2 patients with larger SELs (6.0 cm and 7.5 cm) required conversion to open surgery. The remaining SELs, ranging from 1.2 to 3.0 cm, were resected safely without complications, and no recurrences or metastases were observed. In another study, Ye et al. treated 85 upper gastrointestinal SELs < 3.0 cm with STER, including 60 in the esophagus [16]. They achieved 100.0% en bloc resection, and complications related to perforation occurred in 8 (9.4%) cases, with no recurrences or metastases reported. In our study, among patients with SELs < 3.0 cm, the en bloc resection and retrieval rate was 100.0%, consistent with previous reports and demonstrating rare risk of recurrences or metastases. The incidence of intraoperative and postoperative AEs for SELs < 3.0 cm were 10.1% and 2.9%, respectively, comparable to those reported previously [7, 8, 16]. All patients were safely discharged, highlighting the effectiveness and superiority of STER in treating SELs < 3.0 cm.

For large esophageal SELs, some studies have explored the use of STER [17, 18]. However, previous studies typically focused on the efficacy of STER within specific size ranges, primarily concentrating on SELs between 3.0 and 5.0 cm. Therefore, our research further categorized large SELs into groups of between 3.0 and 5.0 cm and ≥ 5.0 cm to compare their efficacy and safety with those < 3.0 cm.

Among patients with esophageal SELs between 3.0 and 5.0 cm, Wang et al. treated 22 SELs measuring 3.0–5.0 cm with STER, achieving an 86.4% en bloc resection rate and a 100.0% complete resection rate, with a 13.6% perforation rate but no recurrences or metastases [19]. In our study, most tumors were benign, except for 1 suspected of intermediate malignancy. Despite spatial constraints, we achieved successful en bloc resection for all sizes, confirming the efficacy of STER. However, the restricted dimensions of the esophageal lumen and submucosal tunnel sometimes necessitated segmenting larger SELs for effective retrieval [12, 13]. Challenges included 1 intentional tumor segmentation due to extraction difficulties and 1 unintentional fragmentation in a narrow esophageal segment, preventing en bloc retrieval. Despite these issues, the en bloc retrieval rate was 93.5%, demonstrating the efficacy of STER for SELs < 5.0 cm, comparable to that for SELs < 3.0 cm. Additionally, the rates of intraoperative and postoperative AEs were similar between patients with SELs between 3.0 and 5.0 cm and those with SELs < 3.0 cm. Postoperative management for patients with 3.0–5.0 cm SELs did not impose additional burdens compared to those with SELs < 3.0 cm, as reflected in similar hospital stays. Follow-up of 13 patients revealed no recurrences or metastases, further confirming the efficacy and safety of STER for managing 3.0–5.0 cm SELs.

For SELs ≥ 5.0 cm, Chen et al. compared the outcomes of 91 cases of STER with 75 cases of thoracoscopic enucleation (TE) [11]. The en bloc resection rates were 84.6% for the STER group and 86.7% for the TE group. AE rates were 7.7% for STER and 5.3% for TE. No recurrence or metastasis were observed in either group. In this study, for patients with SELs ≥ 5.0 cm who completed STER procedures, we achieved a 100% en bloc resection rate with no recurrence, metastasis, or stenosis, affirming STER as an effective treatment for esophageal SELs ≥ 5.0 cm. However, the en bloc retrieval rate for SELs ≥ 5.0 cm was significantly lower than that for SELs < 3.0 cm due to the limited space within the esophagus. Despite this, given that most esophageal SELs were benign, piecemeal extraction with comprehensive preoperative evaluation remains a practical approach. Additionally, the rates of intraoperative and postoperative AEs, as well as ICU transfer, were higher among patients with SELs ≥ 5.0 cm. Previous studies have demonstrated that factors such as irregular shape and deep location within the MP of esophageal SELs are risks for complications [11, 16, 20]. Our study supports these findings, as all patients with SELs ≥ 5.0 cm who developed pneumoperitoneum had lesions located in the deep MP, and most had irregular shape. This highlights the need for meticulous preoperative planning and postoperative care to mitigate the increased risks and ensure patient safety for SELs ≥ 5.0 cm.

All patients were preoperatively diagnosed with SELs using EUS, endoscopy, or CT. Among patients assessed with EUS, 109 cases received specific diagnoses. Excluding 3 cases with inconclusive postoperative pathology, histopathological examinations confirmed 92 diagnoses, leading to an EUS diagnostic accuracy of 86.8%. Additionally, intraoperative findings revealed that of 9 SELs located in the MM, 6 had been inaccurately classified by EUS as involving the MP. This underscored the potential limitations of EUS in the precise diagnosis of SELs.

The current study had some limitations. Firstly, the sample size was relatively small, especially for patients with large SELs, necessitating larger future studies for more definitive conclusions. Secondly, follow-up compliance and duration were suboptimal, limiting our ability to fully assess long-term outcomes and recurrence rates. Additionally, as a single-center study conducted by expert endoscopists, the results may not be generalizable to settings with different levels of expertise and resources. Multi-center studies are needed to validate these findings. Lastly, the retrospective design may introduce information bias due to potential inaccuracies in medical records and recall. In addition, retrospective study design has resulted in a lack of uniform criteria for patient management (e.g., criteria for referral to the ICU). Prospective studies are recommended to provide a more controlled and accurate assessment of treatment outcomes.

In conclusion, STER is effective and safe for treating esophageal SELs up to 5.0 cm. For larger lesions, the procedure remains viable but requires meticulous planning, advanced techniques and enhanced monitoring to manage increased complexity and risks. This study highlights the need for specialized strategies and advanced training for endoscopists. Further research with larger cohorts and longer follow-up is essential to confirm these findings and refine treatment protocols, ensuring optimal care for all patients.