Natural History of Asymptomatic Small Gastric Subepithelial Tumors

Goal: To assess the natural history of gastric subepithelial tumors (SETs) of <= 30mm in size and to determine their optimal management. Background: Definitive guidelines have not been formulated for the management of small gastric SETs, owing to a lack of knowledge of their natural history and insufficient long-term follow-up. Study: We retrospectively reviewed the upper endoscopy and/or endoscopic ultrasound results of 989 tumors diagnosed as gastric SETs of <= 30mm in size between July 1997 and October 2008 with a minimal follow-up of 3 months. A gastric SET was defined as a mass covered with normal appearing mucosa on upper endoscopy and a tumor located in the second, third, or fourth layer on endoscopic ultrasound. Results: Of the 989 SETs in 948 patients, 84 (8.5%) showed significant changes in size, and/or echogenicity, and/or morphology at a median 24 months (range, 3 to 123 mo). Estimated growth rates differed significantly by initial size (< 10mm, 0.14mm/mo; 10 to 20mm, 0.22mm/mo; 20 to 30mm, 0.31mm/mo; P = 0.003). Twenty-five patients with tumors showing changes in size and/or echogenicity underwent surgical/endoscopic resection; of these, 19 patients were diagnosed with gastrointestinal stromal tumors (GISTs), of which 3 patients were considered at high risk, 4 at intermediate risk, 10 at low risk, and 2 at very low risk. In a univariate analysis, GISTs showed a significant change in tumor size during follow-up compared with other benign tumors (P = 0.037). However, multivariate analysis did not show a statistical significance in size change between GISTs and other benign tumors (hazard ratio 1.754; 95% CI, 0.575 to 5.291; P = 0.326). Conclusions: Only 8.5% of gastric SETs of <= 30mm in size showed significant changes at a median 24 months. SETs of 10 to 30mm in size grew significantly more rapidly than SETs < 10 mm.