title: Correlation of microsatellite instability at multiple loci with long-term survival in advanced gastric carcinoma.
abstract: OBJECTIVE
  Microsatellite instability (MSI) correlates with clinicopathologic characteristics and long-term prognosis in patients having gastric carcinoma.
  
  
  METHODS
  Analysis of prospectively collected data and biologic material.
  
  
  METHODS
  Tertiary University Hospital, Policlinico "Le Scotte," Siena, Italy.
  
  
  METHODS
  Two hundred fifty patients with gastric carcinoma.
  
  
  METHODS
  Five mononucleotide repeats (BAT-26, BAT-25, NR-24, NR-21, and NR-27) were analyzed in these patients.
  
  
  RESULTS
  An MSI phenotype was identified in 63 patients (25.2%) and correlated with specific clinicopathologic characteristics. Favorable prognosis was confirmed for patients with an MSI phenotype in univariate (P < .001) and multivariate (P = .05) analyses. Significant differences in clinicopathologic characteristics and long-term prognoses were observed among patients with microsatellite-stable tumors, tumors having instability at 2 to 4 markers, and tumors having instability at all 5 markers (MSI/5). The MSI/5 phenotype was associated with older age (P < .001), female sex (P = .001), antral tumor location (P = .04), intestinal histotype (P = .003), and less infiltration of the serosa (P = .006); lymph node involvement was rare (P < .001) and was limited to few (median, 3) metastatic lymph nodes (P = .001). Long-term survival of patients with the MSI/5 phenotype is favorable and was confirmed in multivariate analysis (relative risk vs patients with stable tumors, 0.32; 95% confidence interval, 0.16-0.63; P = .002).
  
  
  CONCLUSIONS
  Compared with stable tumors, MSI tumors have distinct clinicopathologic features and are associated with a better prognosis. Patients with the MSI/5 phenotype have a very good prognosis.
authors.affiliation: Sezione di Chirurgia Oncologica, Dipartimento di Patologia Umana e Oncologia, Policlinico Le Scotte, University of Siena, 53100 Siena, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Corso
authors.forename: Corrado
authors.initials: C
authors.lastname: Pedrazzani
authors.forename: Daniele
authors.initials: D
authors.lastname: Marrelli
authors.forename: Valeria
authors.initials: V
authors.lastname: Pascale
authors.forename: Enrico
authors.initials: E
authors.lastname: Pinto
authors.forename: Franco
authors.initials: F
authors.lastname: Roviello
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D016009:Chi-Square Distribution; D005260:Female; D005743:Gastrectomy; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008207:Lymphatic Metastasis; D008297:Male; D053842:Microsatellite Instability; D009367:Neoplasm Staging; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D016019:Survival Analysis
chemical_list: D014408:Biomarkers, Tumor