title: Clinical effects of adjuvant active specific immunotherapy differ between patients with microsatellite-stable and microsatellite-instable colon cancer.
abstract: OBJECTIVE
  Active specific immunotherapy (ASI) consisting of an autologous tumor cell vaccine given as adjuvant treatment has been shown to improve recurrence-free survival of patients with colon cancer. The aim of the current retrospective study was to investigate whether the beneficial effects of ASI given as adjuvant treatment correlated with microsatellite instability (MSI), which is considered an important biologic determinant of colon cancer.
  
  
  METHODS
  Microsatellite status was assessed on archival tumor material from patients with stage II and III colon cancer. Microsatellite status was next associated with clinical outcome in control and ASI treatment groups using Kaplan-Meier analysis.
  
  
  RESULTS
  We identified 162 (83%) microsatellite-stable tumors (MSS) and 34 (17%) MSI tumors. Patients with MSI tumors did well in recurrence-free interval (RFI) as well as disease-specific survival (DSS) irrespective of treatment arm and tumor stage. Patients with MSI tumors had significantly fewer recurrences and prolonged DSS than those with MSS tumors. Patients with MSS Dukes B tumors who received ASI treatment showed a significantly improved recurrence-free survival compared with controls. ASI treatment did not improve recurrence-free interval or DSS for patients with MSS Dukes C tumors.
  
  
  CONCLUSIONS
  This retrospective study indicated that patients with MSI tumors did well, irrespective of treatment arm and tumor stage. The data also indicate that the clinical benefit, measured as recurrence-free survival, from adjuvant ASI treatment of patients with colon cancer was restricted to patients with MSS Dukes B tumors.
authors.affiliation: Department of Pathology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: de Weger
authors.forename: Annelies W
authors.initials: AW
authors.lastname: Turksma
authors.forename: Quirinus J M
authors.initials: QJ
authors.lastname: Voorham
authors.forename: Zelda
authors.initials: Z
authors.lastname: Euler
authors.forename: Herman
authors.initials: H
authors.lastname: Bril
authors.forename: Alfons J
authors.initials: AJ
authors.lastname: van den Eertwegh
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bloemena
authors.forename: Herbert M
authors.initials: HM
authors.lastname: Pinedo
authors.forename: Jan B
authors.initials: JB
authors.lastname: Vermorken
authors.forename: Harm
authors.initials: H
authors.lastname: van Tinteren
authors.forename: Gerrit A
authors.initials: GA
authors.lastname: Meijer
authors.forename: Erik
authors.initials: E
authors.lastname: Hooijberg
mesh_terms: D019496:Cancer Vaccines / Q000627:therapeutic use*; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D006801:Humans; D016233:Immunotherapy, Active; D053208:Kaplan-Meier Estimate; D053842:Microsatellite Instability; D018895:Microsatellite Repeats; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D012189:Retrospective Studies
chemical_list: D019496:Cancer Vaccines