In Western countries, endoscopic resection (ER) of gastric subepithelial lesions (SELs) is emerging as an alternative to either surveillance for lesions <20 mm or surgical resection in cases with suspected malignant potential (such as GISTs >20 mm or type 1 neuroendocrine neoplasms >10 mm). Several endoscopic resection techniques have been proposed. This study reports a cohort of patients with gastric SELs who underwent endoscopic resection using a modified-STER (submucosal tunneling endoscopic resection) approach, defined as “FLAP technique”

Data from consecutive patients with gastric SELs who underwent ER were collected. All patients underwent endoscopic ultrasonography (EUS) prior to the ER. Patients’ characteristics, SELs features, and endoscopic procedure details were collected. The “FLAP technique” consists in creating a short submucosal access, less than 1 cm proximal to the lesion (closer than the originally tunnel described at 5 cm), followed by careful dissection of the lesion while preserving the capsule and the overlying mucosal flap. If the lesion is deeply adherent to muscolaris propria (MP), a transmural resection is performed, resulting in a controlled and intentional perforation of the MP and serosa. After removal and retrieval of the specimen, hemostatic gel is applied and the defect is completely closed with clips using the mucosal flap. Technical success was considered as complete endoscopic resection and retrieval of the specimen; clinical success as an en-bloc and R0 resection. Intraprocedural, short term and long-term adverse events (AEs) and complication have been registered. 

A total of 6 patients (50% male, mean age 60 yr) with 6 SELs were included. Median SELs size was 16.5 mm (IQR), 50% located in the antrum and 50% located in gastric body. In 83% cases MP involvement was described at EUS. Technical success was achieved in 5/6 patients. The technical unsuccessful procedure, a 30 mm SELs of the grater curvature of the gastric body with a predominant extraluminal extension, was suspended due to the impossibility to endoscopic retrieve the lesion, with a high risk of lesion migration into the peritoneum.; the patient underwent laparoscopic wedge resection. Clinical success (en bloc and R0) was achieved in 5/5 patients with preservation of the capsule in 100% of the cases. To achieve complete tumor removal a transmural resection was required in 60% of cases. Total closure of the defect using the mucosal flap and clips was achieved in 100% of the patients. Histopathology showed a low-risk GIST and benign lesions in other cases. Median total procedure time was 100 minutes. No AEs occurred during or after the procedure. 

In selected cases, endoscopic resection of SELs is feasible, efficient and safe, also in a Western setting. In our experience preserving the mucosal flap is usefull to allow easy and complete endoscopic closure. Creation of a shorter submucosal access did not compromise the integrity of mucosal flap. More data or comparative studies are needed to assess endoscopic resectability and retrival criteria and optimal removal techniques for SELs.