title: Gene mutations and prognostic factors analysis in extragastrointestinal stromal tumor of a Chinese three-center study.
abstract: BACKGROUND
  Most gastrointestinal stromal tumors (GISTs) have gain-of-function mutation of the c-kit gene, and some have mutation of the platelet-derived growth factor receptor-α (PDGFR-α) gene. Extragastrointestinal stromal tumors (EGISTs) are mesenchymal tumors that occur outside the digestive tract. But the clinicopathologic characteristics of EGISTs are still poorly understood.
  
  
  METHODS
  Paraffin-embedded tissues from 25 cases of EGIST were analyzed for CD117, CD34, Ki-67, S-100, smooth muscle actin, and desmin expression by immunohistochemical method. These cases of EGISTs were also evaluated for the presence of c-kit exons 9, 11, 13, and 17 mutations and PDGFR-α exons 12 and 18 mutations. Survival analysis was used to evaluate the prognostic factors.
  
  
  RESULTS
  c-kit mutations were detected in 44% of EGIST patients and all were exon 11 mutations. PDGFR-α mutations were found in 12% of the 25 cases and all were exon 18 mutations. Survival analysis indicated that mitotic count and Ki-67 labeling index (Ki-67 LI) were significant predictors of survival.
  
  
  CONCLUSIONS
  The pattern of c-kit and PDGFR-α mutation in EGISTs was essentially similar to that in GISTs. From the molecular genetics aspect, EGISTs may be a special subtype of GISTs. The results also show that the combination of mitotic counts and Ki-67 LI may be useful for predicting the prognosis of EGISTs.
authors.affiliation: Department of Oncology, Hangzhou First People's Hospital of Zhejiang Province, Hangzhou 310006, China. tztree@126.com
authors.forename: Song
authors.initials: S
authors.lastname: Zheng
authors.forename: Ke-er
authors.initials: KE
authors.lastname: Huang
authors.forename: De-you
authors.initials: DY
authors.lastname: Tao
authors.forename: Yue-long
authors.initials: YL
authors.lastname: Pan
mesh_terms: D000008:Abdominal Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008643:Mesentery; D008875:Middle Aged; D008940:Mitotic Index; D009154:Mutation; D009852:Omentum; D010386:Pelvic Neoplasms / Q000235:genetics / Q000473:pathology; D010534:Peritoneal Neoplasms / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics*; D012186:Retroperitoneal Neoplasms / Q000235:genetics / Q000473:pathology; D016019:Survival Analysis
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha