Long‐Term Outcomes of Gastric Subepithelial Lesion of < 2 cm and Risk Factors for Tumor Growth

ABSTRACT Background and aim Endoscopic resection of small gastric subepithelial lesions (SELs) has been recently reported. However, evidence of natural history of untreated small gastric SELs is lacking. This study aimed to investigate the long‐term course of gastric SELs of < 2 cm as well as identify the enlargement rate and factors affecting it. Methods A total of 1045 gastric SELs in 1033 patients were evaluated via endoscopic ultrasonography (EUS) from January 1994 to December 2023. Of these, this study included 125 SELs in 122 patients with an initial tumor diameter of < 2 cm and who underwent at least two EUS examinations. Tumor diameter was measured through EUS and considered enlarged when the longitudinal diameter increased > 1.25 times from the initial size. Multivariate Cox proportional hazards regression analysis was used to identify factors affecting tumor enlargement. Results The average observation period was 4.0 ± 3.4 years. A total of 29 (23.2%) lesions were enlarged during the observation period, with a mean tumor doubling time of 4.1 ± 3.8 years and an augmentation rate of 5.7/100 person‐years. The multivariate analysis indicated that the initial tumor size of ≥ 9.5 mm (hazard ratio [HR]: 3.99, 95% confidence interval [CI]: 1.33–11.94) and EUS finding changes (irregular border, cystic space, high echoic lesion, and/or heterogeneity), excluding calcifications (HR: 2.55, 95% CI: 1.09–5.97), were increasing factors. Conclusions The augmentation rate of gastric SELs of < 2 cm was 5.7/100 person‐years. These results provide valuable data for treatment decisions.