OBJECTIVETo investigate the clinicopathological features of small gastrointestinal stromal tumors(GISTs) and to evaluate the efficacy of endoscopic therapy for GISTs.

METHODSClinicopathological and follow-up data of 418 patients with GISTs undergoing endoscopic therapy in the Zhongshan Hospital between January 2009 and July 2014 were analyzed retrospectively. All the cases were evaluated by the NIH risk classification and AIFP classification, and were grouped according to the tumor size and location. Nuclear atypia and mitotic count were used to evaluate the biological behavior of small GIST. Efficacy of endoscopic therapy was analyzed with follow-up data.

RESULTSOut of 418 patients, GISTs located in the esophagus was 14(3.3%), in the stomach 389(93.1%), in the duodenum 5(1.2%), in the rectum 10(2.4%). A total of 412(98.6%) patients were mainly spindle cells, and mitosis was not found in 320(76.5%) patients. In 389 small stomach GIST, 245(58.6%) were in fundic region. Cases were divided into four groups according to the size and the result revealed the bigger the size, the more the mitotic count. Nuclear atypia in the 1.5-1.9 cm group was significantly higher compared to other groups. Cases were divided into four groups according to the location and the result revealed the mitotic count was not associated to the location. While the nuclear atypia of stomach GIST was significantly higher than that of esophageal GIST and the nuclear atypia of rectum GIST was significantly higher than that of other positions. The median follow-up was 32(4-69) months. One case(gastric fundus GIST, >1.5 cm) presented local recurrence 23 months after operation and underwent endoscopic resection again. No recurrence or metastasis was found in other patients.

CONCLUSIONSEndoscopic resection technique is effective for small GISTs patients. The small GISTs with 0.4 cm diameter or less are often benign and should be followed up for long time. The small GISTs with 0.5 cm diameter or more possess the risk of malignancy, then surgical resection should be performed. Rectum small GISTs (except for 0.4 cm diameter or less) have worse biological behavior and should be removed.