Natural History of Gastric Subepithelial Tumors: Long-Term Outcomes and Surveillance Strategies

Gastric subepithelial tumors (SETs) are commonly identified during routine endoscopy. Most SETs are asymptomatic and small (<2 cm) and exhibit benign behavior over time. Various histopathological types exist, including benign lesions, such as lipomas and heterotopic pancreas, and malignant lesions, such as gastrointestinal stromal tumors (GISTs). Endoscopic ultrasound (EUS) plays a critical role in evaluating the lesion size, layer of origin, border characteristics, and internal echogenicity. Approximately 4-15% of gastric SETs increase in size over ~5 years. The risk factors for the growth and malignant potential of SETs include initial tumor size, irregular or heterogeneous EUS features, mucosal ulceration, and confirmed GIST diagnosis. While lesions ≥2 cm in size or those with high-risk features are typically subjected to resection, small and low-risk SETs are managed with periodic EUS or endoscopic surveillance. Tissue acquisition via EUS-guided biopsy or endoscopic resection is warranted for indeterminate or suspicious cases. A risk-stratified approach minimizes unnecessary interventions while enabling timely detection of clinically significant lesions. Surveillance protocols should be tailored according to characteristics of SETs, patient comorbidities, and diagnostic confidence. This review highlights the long-term outcomes of gastric SETs, evaluates established risk factors for their growth and malignant potential, and discusses evidence-based strategies for surveillance and management.