Natural History of Gastric Subepithelial Lesions Measuring 1 to 2 cm.

Objectives: Management strategies for subepithelial lesions (SELs) measuring 1-2 cm remain undefined in most guidelines due to limited data. We aimed to establish a practical clinical approach by analyzing the long-term outcomes of SELs in this size range. Methods: We retrospectively reviewed cases of gastric SELs measuring 1-2 cm between 2011 and 2023. We reviewed esophagogastroduodenoscopy and endoscopic ultrasound images, alongside data from abdominal computed tomography, biopsy results, and long-term follow-up records. Results: Gastric SELs were initially identified in 648 patients. Of these, 88 patients (mean age, 57.1±10.6 years; 60% women) had lesions measuring 1-2 cm and underwent further evaluation or surveillance. The mean lesion size determined by endoscopy was 13.7±3.3 mm. Among the 52 patients with histological confirmation, 24 (46%) were diagnosed with gastrointestinal stromal tumors (GISTs), whereas the remainder had benign lesions. Most gastric SELs were located in the fundus and upper body. Pathological analysis indicated that the majority of GISTs were low-risk. Three GISTs were stratified as moderate-to-high risk; notably, one measured 0.9 cm upon pathological examination. The median surveillance period for the 28 patients without histological confirmation was 55 months (range, 43-115 months). Two of these patients underwent endoscopic or wedge resection due to tumor enlargement; both lesions were histologically confirmed as low-risk. Conclusions: Approximately half of the gastric SELs measuring 1-2 cm were GISTs, representing an intermediate- to high-risk tumors. Given that GISTs in the upper stomach were associated with elevated risk even when smaller than 2 cm, we recommend strict short-term surveillance for such lesions.