Microscopic positive tumor margin does not increase the rate of recurrence in endoscopic resected gastric mesenchymal tumors compared to negative tumor margin

The endoscopic resection of gastrointestinal mesenchymal tumors (GIMTs) is widely accepted because of its minimal invasiveness. However, one major concern is the high rate of positive microscopic margins remaining following endoscopic resection, which was thought to be related to a higher risk of recurrence. This study aimed to determine whether positive margins affect the recurrence rate of gastric GIMTs and the factors associated with positive margins.Patients with gastric GIMTs were recruited retrospectively from January 2008 to December 2013. Clinical and pathological features, endoscopic procedure information, and follow-up data were collected and analyzed.The study included 777 patients. All tumors were removed along with the pseudocapsule without macroscopic residual (ER0), and the median tumor size was 15.2 mm (range 3-100 mm). Pathological evaluation revealed 371(47.7%) GISTs. The rate of microscopic R1 resection rate was 47.0% (443/777). In a stepwise multivariate analysis, a significantly increased incidence of R1 resection was recorded for the GISTs (OR 11.13, 95% CI 3.00-41.37). In a subgroup analysis of GISTs, a univariate analysis revealed that EFTR achieved a higher rate of R0 resection (OR 0.56, 95% CI 0.31-1.00), but it was proven insignificant in a stepwise multivariate analysis. Local recurrence occurred in two patients (0.3%) during a mean follow-up time of 34.2 months. Differences in the recurrence rates between the R0 and R1 groups were statistically insignificant (P = 0.841).R1 resection for gastric GIMTs is not related to a higher recurrence rate than R0 resection, and ER0 resection is sufficient for gastric GIMTs.