Retrospective analysis of extra-gastrointestinal stromal tumors

AIM:To investigate the clinicopathologic features of patients with extra-gastrointestinal stromal tumors(EGISTs)in South Korea.METHODS:A total of 51 patients with an EGIST were identified.The clinicopathologic features,including sex,age,location,tumor size,histology,mitotic rate,immunohistochemical features,genetic status and survival data,were analyzed.RESULTS:The median age was 55 years(range:29-80years),and male:female ratio was 1:1.04.The most common site was in the mesentery(n=15)followed by the retroperitoneum(n=13)and omentum(n=8).The median tumor size was 9.0 cm(range:2.6-30.0cm)and the median mitotic rate was 5.0/50HPF.(1/50-185/50).KIT was analyzed in 16,which revealed 10cases with wild-type KIT and 6 cases with an exon 11mutation.Among 51 patients,31 patients had undergone surgery,and 10 had unresectable disease and had taken palliative imatinib,which resulted in 22.7 mo of progression-free survival.Of the patients who had undergone surgery,18 did not take adjuvant imatinib,and 8 of these were categorized as"high risk"according to the risk criteria.However,the relapse-free survival was not different(P=0.157)between two groups.CONCLUSION:Because the biologic behaviors of GISTs differ according to the location of the tumor,a more stratified strategy is required for managing EGISTs including incorporation of molecular features.