Herein, we reported a hybrid EFTR with minimal surgical intervention—EROPP—for gastric GISTs. EROPP has an important advantage of being able to keep the intra-abdominal pressure constant. This eliminates concerns about intra-abdominal compartment syndrome originating from the pneumoperitoneum and contributes to maintain the good visual endoscopic field. Consequently, we were able to obtain good treatment outcome for gastric GISTs despite a lack of experience with pure EFTR.
EFTR has been introduced as a treatment option for gastric GISTs (< 4 cm) originating from the muscularis propria, according to the American Society for Gastrointestinal Endoscopy (ASGE) guidelines.[5] However, pure EFTR has not been widely adopted in clinical practice. One of the barriers of pure EFTR is the management of pneumoperitoneum and how to prevent collapse in the gastric lumen. Pure EFTR procedures can potentially cause dangerously high pneumoperitoneum. Additionally, the intentional perforation of the gastric wall leads to an unclear visual field because intragastric gases could escape into the peritoneal cavity [6]. To overcome this, we tend to insufflate the lumen continuously to maintain a good visual field. This may cause excessive pneumoperitoneum, which gives rise to abdominal compartment syndrome. Although previous studies revealed that needle decompression can decompress the abdominal cavity, this can prevent the provision of a good endoscopic visual field after luminal collapses by intentional perforation[3, 6, 7]. In an experiment performed in pigs, Kamba et al. reported that the intra-abdominal pressure and the intragastric luminal pressure during EFTR were in equilibrium[8]. From this, it is considered that when the abdominal cavity is collapsed with a puncture needle, the gastric luminal pressure is also significantly reduced, which hinders the securing of the endoscopic visual field. Especially for endoscopists who have no experience with EFTR, collapse of the gastric lumen is a technical obstacle. In this case series, however, the intra-abdominal pressure was monitored and adjusted via a port during the procedure, thus enabling the procedure without any concern of excessive pneumoperitoneum. Additionally, maintaining a constant intra-abdominal pressure from the port also maintains the intra-gastric luminal pressure, which leads to a good endoscopic field of view during the procedure. For this reasons, en bloc resection could be achieved in all cases and R0 resection in most cases, which also resulted in a relatively short procedural time.
Another barrier for using pure EFTR is the absence of reliable endoscopic full-thickness suturing devices. Various methods and devices are available for gastric wall closure[9, 10]. A recent report suggested that OTSCs can be used to perform EFTR with defect closure for gastric tumors in the muscularis propria (tumor diameter < 2 cm)[11]. Similarly, this case series demonstrated that gastric full-thickness defects were successfully closed with OTSCs in all 14 cases. As shown in our video, the OTSC closure system enables us to achieve inverted seromuscular apposition[12, 13]. A previous study indicated that inverted serosal apposition provides a more durable and reliable repair than everted mucosal apposition[14]. In this procedure, defect closure using OTSCs is more reliable than purse-string suturing using an endoloop and endo-clips. In addition, when large defects led to incomplete closures, additional OTSCs or endo-clips were used to close the remaining portions, resulting in robust closure. Therefore, OTSC may be a reliable endoscopic full-thickness suturing device, given the uneventful postoperative course in this case series. When tumors are positioned on the gastric posterior wall, or the lesser or greater curvature sides, which are covered with fat tissue, the EFTR site may not be visible using one-port laparoscopic observation. However, even in such situations, a leak test can be performed by inflating the gastric lumen and confirming that the intra-abdominal pressure does not increase. Of course, where we can see the EFTR site with a laparoscopic camera, we can directly observe that the EFTR site is inverted and robustly closed. In this case series, all the gastric wall defects were successfully closed with OTSCs without requiring laparoscopic closure. This could be explained by the fact that the control and monitoring of intra-abdominal pressure via a port contribute to maintaining a good endoscopic field of view during the closure procedure. In addition, as shown on the video, when the liver interfered the laparoscopic view, we could immediately check the condition of the endoscopic closure via the laparoscopic view by retracting the liver through an additional port. Furthermore, if the defects were technically difficult to close in EROPP, we could immediately convert it to a laparoscopic hand-sewn closure using additional port access.
The LECS technique was developed in Japan as a gastric wedge resection procedure with minimal transformation of the stomach[15]. Since its inception, LECS-related procedures have developed rapidly, spreading not only in Japan but also worldwide[1]. According to the ASGE guideline, LECS was described as a hybrid EFTR, which is combined endoscopic and laparoscopic technique [5],[16]. On the other hand, most studies of pure EFTR for gastric GISTs have been performed in China[2–4]. A previous review article of pure EFTR reported that conversion to surgery due to either EFTR failure or adverse events was needed in only 0.8% of the procedures[17]. However, this procedure, which is dominated by experience from China, is still controversial in its global spread. Our EROPP, hybrid EFTR with minimal laparoscopic intervention, is excellent not only in terms of safety but also in the introduction of EFTR procedures and has the potential to be globally accepted. Our EROPP procedure is minimally invasive, compare to conventional hybrid EFTR as it requires less gastric wall resection and no omental resection, thereby preserving normal gastric emptying. In addition, our procedure is better than conventional hybrid EFTR in terms of cosmetic outcomes because most of the EROPP procedures were performed with only one port access in this case series. Although the indication for our EROPP is similar to that for conventional hybrid EFTR, the size of GISTs was no more than 35 mm in diameter in this case series, which is smaller than the indication for conventional hybrid EFTR since it is challenging to remove tumors > 35 mm diameter through the oral cavity. In terms of damage to the abdominal wall, pure EFTR is a less invasive treatment compared with our EROPP. However, as previously stated, many concerns about pure EFTR have not been addressed yet with currently available methods and devices. Because the efficacy and safety of pure EFTR remain poorly understood in the countries where pure EFTR has not been popularized, we should consider safety as a top priority. Our case series suggest that port assistance plays an important role to address many concerns about pure EFTR. Furthermore, with the experience of EROPP, we believe that inexperienced endoscopists were the catalyst for the introduction of EFTR and more endoscopists could learn the pure EFTR technique safely.
There are certain limitations in our study. First, this is a retrospective, single-center study. Second, the number of patients was small, requiring validation of our results in larger sample sizes. Moreover, endoscopic procedures in this case series were performed by an experienced endoscopist at a high-volume center.
To conclude, EROPP may be a safe, less invasive hybrid EFTR for gastric GISTs. The experience of EROPP may make pure EFTR more accessible to endoscopists with limited or no experience in pure EFTR.