Although rectal neuroendocrine tumors (RNETs) are relatively uncommon, their incidence has increased due to widespread use of screening colonoscopy and advancements in endoscopic technology [1]. The majority of RNETs are detected at stage 1 or 2, featuring excellent long-term prognosis with 5-year survival rates ranging from 74–88% [1, 10, 11]. Typically, 80–90% of these tumors are less than 1 cm in size, are low grade, exhibit rare metastasis (< 3%), and are diagnosed early in a well-differentiated state confined to the submucosa [4, 12]. Current guidelines from the European Neuroendocrine Oncology Society (ENETS) recommend endoscopic resection for well-differentiated tumors smaller than 10 mm due to their minimal risk of lymphatic and vascular invasion and low malignancy potential [6, 13, 14].
Various treatment strategies for the endoscopic resection of RNETs include standard snare polypectomy, EMR, EMR band ligation, EMR cap placement, underwater EMR, EMR ligation (EMR-L), ESD, ESD muscle ligation (ML), and endoscopic full-thickness resection (eFTR). Although complete resection rates for these techniques are reported to be between 88% and 100%, the optimal treatment method is still a subject of debate [6–8, 15–17]. Endoscopic resection of RNETs aims for en bloc and complete resection. If an R1 lesion is identified after endoscopic resection, and the lesion is confirmed to be G1 with no risk factors, lymphatic or vascular invasion, a second endoscopic resection can be conducted without the need for additional imaging tests. Achieving an R0 resection status in this subsequent procedure may obviate the need for further follow-up. Thus, salvage procedures may be required to ensure complete lesion removal. [6, 7] When RNET was considered a polyp before the endoscopic procedure, the complete resection rate was 68.2%, and when RNET was diagnosed or suspected, it was reported to be 94.5% [5, 18, 19].
If an initial endoscopic procedure results in incomplete resection, subsequent observations often reveal scarring, ulceration, and deformation of the dissection surface at the lesion site during the second endoscopy. These conditions complicate the lifting and dissection processes, thereby hindering the salvage resection of the residual tumor. Consequently, if an RNET is macroscopically suspected and a further endoscopic resection is planned, biopsies should be minimized to avoid exacerbating these issues. Moreover, the choice of optimal treatment, even for salvage procedures, remains a subject of clinical debate [5, 13]. Traditional endoscopic polypectomy is not typically recommended for RNET resections because it usually does not achieve adequate and complete lesion removal and may necessitate additional interventions [6, 13, 20]. Anatomical alterations caused by previous interventions often damage rectal layers, complicating the use of lifting techniques or other adjunctive methods and potentially leading to further complications.
These challenges have prompted a paradigm shift and spurred the development of a simplified, single-step wide hot snare polypectomy technique. By improving the polypectomy technique, it is anticipated that the procedure can be performed more efficiently and safely, without the need for complex additional steps that increase the risk of complications. This innovative approach integrates damaged layers into a single, streamlined procedure, enhancing efficiency and safety while reducing the likelihood of complications.
In our study, we applied the wide hot snare polypectomy to early-stage small RNETs, which are typically located in the mid to lower rectum and confined to the submucosa, thus not necessitating advanced endoscopic techniques.
Early-stage small RNETs, particularly those without risk factors and located in the mid to lower rectum, typically require fewer advanced endoscopic techniques due to their confinement to the submucosa. Sufficient margins were secured by holding the guide wire widely around the lesion and tightening it in the direction of the lesion, and resection was possible with similar effect without lifting. The lifting principle resembled that of Underwater EMR, but it offered the advantage of achieving a comparable effect without the need for the cumbersome process of water filling [9]. The R0 resection rate was 72.7%, which was significantly higher than the 49.5% in the EMR/ESD group. In reality, excluding no residual tumor and uncheckable margin, the positive margin was 0%. Additionally, the average procedure time was 3.5 minutes, which was significantly shorter than 8.3 minutes, and no complications were observed after the procedure. This result proved that sufficient treatment can be achieved with wide hot snare polypectomy. This is a procedure that can be performed by any endoscopist skilled in polypectomy and does not require special skills or special equipment.
Our study has several limitations. Firstly, the small number of patients in this study is attributed to the rarity of RNETs. Additionally, being a retrospective study conducted at a single institution, there is a possibility of selection bias. Secondly, the outcomes for the EMR/ESD group were lower compared to other studies. The EMR/ESD procedures require a lifting process through injection, which can be problematic in salvage operations where the submucosal layers have already been compromised by the initial procedures, increasing the likelihood of difficulties or failures in progressing through each step. Furthermore, the variability in endoscopists and their techniques contributes to these inconsistent results. Despite these limitations, the significance of our study lies not in demonstrating the inadequacy of EMR/ESD, but rather in showing that good outcomes can still be achieved with wide hot snare polypectomy—a technique generally not recommended for RNETs. This finding underscores the potential of refined polypectomy techniques to produce effective results even in challenging cases.
In conclusion, our study demonstrates that wide hot snare polypectomy as part of salvage treatment is a swift, uncomplicated, secure, and efficient choice for rectal NETs < 10 mm in the absence of risk factors. The procedure's simplicity, requiring no additional steps or instruments, is a significant advantage, making wide hot snare polypectomy a potential therapeutic alternative for other small tumors as well.