Full Thickness en bloc Endoscopic Resection of Muscularis-based Subepithelial Tumors (SETs)

Abstract

Figure: No Caption available.Purpose: Most upper GI SETs are gastrointestinal stromal tumors (GISTs), which are potentially malignant. Since risk stratification is dependent on size and mitotic rate, evaluation of SETs includes endoscopic sampling via EUS-guided FNA or core biopsy, “well” biopsies or methods to remove the overlying mucosa followed by direct tumor sampling. These conventional methods only yield a definitive diagnosis in about 60-70% of cases and do not provide sufficient tissue for mitotic rate assessment. Therefore, NCCN and other guidelines recommend surgical resection of all SETs that are known or suspected GISTs ≥2 cm and lifelong endoscopic surveillance of those <2 cm. This approach generates a large burden of surgery and endoscopy for SETs <5 cm the majority of which are low risk. Furthermore, for SETs at the GE junction esophagus or cardia laparoscopic “wedge” resection may be challenging or impossible. Over the past decade enterprising endoscopists mostly from Asia have extended the technique of ESD (endoscopic submucosal dissection) to enucleation of SETs. However, the concern with using ESD to enucleate muscularis propria (MP) based SETs such as GISTs is that microscopic residual tumor may remain in the muscularis propria. Novel superior closure devices and methods have led to development of endoscopic full thickness resection techniques for SETs. Direct transmural endoscopic full thickness resection (EFTR) has been reported by groups in Asia over the past year. Unlike traditional ESD, EFTR can achieve complete en bloc resection of MP-based SETs along with the associated MP thus ensuring R0 curative resection. Methods: We review the literature and present two cases of complete endoscopic removal of muscularis based SETs in the gastric fundus using EFTR. These two videos represent two cases from our series of EFTR for SETs, including the first such cases reported in the United States. Results: Complete resection was achieved under deep sedation with short procedure times and no signifi cant adverse events. Primary closure was achieved using an endoscopic suturing device. Histopathological examination revealed very low risk GISTs. No further endoscopic surveillance required. Conclusion: These techniques represent a NOTES approach to resection of tumors <5 cm. Advantages include: 1. Incisionless approach. 2. Wedge resection of SETs in areas that challenge laparoscopic “wedge” resection such as the GE junction, esophagus and gastric cardia. 3. Reliable diagnosis and mitotic rate assessment which along with complete resection obviates lifelong endoscopic surveillance for low risk tumors. Disclosure - Dr. Stavropoulos Boston Scientific, Honorarium and ERBE, Honorarium.