title: [Association between microsatellite instability and clinico-pathological characteristics in sporadic colon cancer].
abstract: OBJECTIVE
  Currently, colon cancer is a leading cause of cancer death world-wide. It progresses according to three molecular pathways, named suppressor, mutador and methylator. Microsatellite instability is a hallmark of the lack of reparation, of DNA mismatches and it characterizes a subset of colon tumors (unstable tumors, MSI). MSI-H patients (high degree of microsatellite instability) seem to share clinico-pathological differences with MSS (microsatellite stable) and MSI-L (low degree of microsatellite instability) patients. In this study, associations between high degree of microsatellite instability and pathological (location, mucinous content, differentiation grade, stages T3N0, stages II and III) and clinical features (response to chemotherapy, disease-free survival and overall survival) were evaluated.
  
  
  METHODS
  117 patients with sporadic colon cancer were classified into two populations (MSS/MSI-L and MSI-H) by using PCR and electrophoresis of seven microsatellites, according to the National Cancer Institute recommendations.
  
  
  RESULTS
  MSI-H tumors tended to be located in the right colon (p = 0.022) and were of mucinous histologic type (p = 0.04). No differences in disease-free survival and overall survival between group of stage II and III patients with MSS/ MSI-L and corresponding ones with MSI-H colon cancer were found (p = 0.54, p = 0.37, respectively). Conversely, MSI-H patients with stage II colon cancer had a favourable prognosis (p = 0.027). Nevertheless, response to 5-fluorouracil (5-FU) and leucovorin was similar in MSS/ MSI-L and MSI-H groups (p = 0.38).
  
  
  CONCLUSIONS
  MSI-H patients are characterized by certain pathological features; those MSI-H patients with a stage II seem to have a better prognosis than MSS/ MSI-L patients.
authors.affiliation: Centro de Investigación Biomédica. Servicio Navarro de Salud. Pamplona, Navarra, España. dguerres@cfnavarra.es
authors.forename: David
authors.initials: D
authors.lastname: Guerrero
authors.forename: Enrique
authors.initials: E
authors.lastname: Balen
authors.forename: José María
authors.initials: JM
authors.lastname: Martínez-Peñuela
authors.forename: Jesús
authors.initials: J
authors.lastname: García-Foncillas
authors.forename: Begoña
authors.initials: B
authors.lastname: Larrinaga
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Caballero
authors.forename: Javier
authors.initials: J
authors.lastname: Herrera
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Lera
mesh_terms: D003110:Colonic Neoplasms / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D053842:Microsatellite Instability