title: Monitoring of loss of heterozygosity in serum microsatellite DNA among patients with gastrointestinal stromal tumors indicates tumor recurrence.
abstract: BACKGROUND
  Patients with gastrointestinal stromal tumors (GIST) harbor increased levels of circulating tumor DNA in their peripheral blood. In the current study, the aim was to investigate whether the frequency of loss of heterozygosity (LOH) on cell-free DNA in blood may reflect tumor stage and recurrent disease of these patients.
  
  
  METHODS
  Serum DNA and follow-up samples of 92 patients suffering from recurrent GIST were analyzed by a PCR-based fluorescence microsatellite analysis using a panel of 12 polymorphic markers. The data were correlated with established risk factors, and patients were followed-up over 4 y.
  
  
  RESULTS
  Microsatellite analysis demonstrated a positive LOH score on cell-free DNA of 30/92 patients. A significant correlation with recurrence in CT imaging showed that a positive LOH score (n ≥ 2) was detected in 58% (11/19) of patients with recurrent disease (P = 0.030, χ(2) test), but only in 25% of patients were clinically free of recurrence. No prognostic significance of a positive LOH score was observed after a median observation time of 48 mo.
  
  
  CONCLUSIONS
  Our findings show that LOH on circulating serum DNA correlates with the tumor status and is a frequent event in GIST patients with recurrent disease.
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Tamina
authors.initials: T
authors.lastname: Rawnaq
authors.forename: Heidi
authors.initials: H
authors.lastname: Schwarzenbach
authors.forename: Paulus G
authors.initials: PG
authors.lastname: Schurr
authors.forename: Kathrin
authors.initials: K
authors.lastname: Freise
authors.forename: Stephan
authors.initials: S
authors.lastname: Brandl
authors.forename: Jakob R
authors.initials: JR
authors.lastname: Izbicki
authors.forename: Jussuf T
authors.initials: JT
authors.lastname: Kaifi
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood; D004273:DNA, Neoplasm / Q000097:blood* / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D046152:Gastrointestinal Stromal Tumors / Q000097:blood* / Q000000981:diagnostic imaging / Q000235:genetics; D006801:Humans; D008137:Longitudinal Studies; D019656:Loss of Heterozygosity / Q000235:genetics*; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm