title: Prognostic significance of MRP5 immunohistochemical expression in glioblastoma.
abstract: BACKGROUND
  Glioblastoma multiforme (GBM) is the most frequent malignant primary brain tumor in adults, exhibiting poor survival. The efficacy of chemotherapy is often limited by the development of multidrug resistance by the tumor cells. In the current study, we investigated the prognostic significance of the multidrug resistance protein 5 (MRP5) in patients with GBM.
  
  
  METHODS
  We retrospectively studied 33 patients with GBM treated with a combination of surgery, postoperative radiotherapy and adjuvant temozolomide chemotherapy. MRP5 protein expression was determined immunohistochemically and correlated with other prognostic factors and survival.
  
  
  RESULTS
  The immunohistochemical expression of MRP5 was observed in 0-45% of tumor cells. Patients with MRP5 index >11% exhibited significantly worse survival compared to those with MRP5 index ≤ 11 (10.5 vs. 18 months, p = 0.0002). Patients with Ki-67 index lower than 30% had longer survival (15 vs. 11 months, p = 0.0084). Furthermore, patients with a gross total tumor excision had better survival (p = 0.016). No significant difference was observed between preoperative Karnofsky performance score, age, gender and survival. In multivariate analysis, MRP5 index and the extent of tumor resection were identified as factors with independent prognostic power.
  
  
  CONCLUSIONS
  The present results imply that MRP5 index may hold a prognostic role in patients with GBM.
authors.affiliation: Department of Neurosurgery, University Hospital of Ioannina, Ioannina, Greece. alexiougrg@yahoo.gr
authors.forename: George A
authors.initials: GA
authors.lastname: Alexiou
authors.forename: Anna
authors.initials: A
authors.lastname: Goussia
authors.forename: Spyridon
authors.initials: S
authors.lastname: Voulgaris
authors.forename: Andreas D
authors.initials: AD
authors.lastname: Fotopoulos
authors.forename: George
authors.initials: G
authors.lastname: Fotakopoulos
authors.forename: Antigoni
authors.initials: A
authors.lastname: Ntoulia
authors.forename: Anastasia
authors.initials: A
authors.lastname: Zikou
authors.forename: Perikles
authors.initials: P
authors.lastname: Tsekeris
authors.forename: Maria I
authors.initials: MI
authors.lastname: Argyropoulou
authors.forename: Athanasios P
authors.initials: AP
authors.lastname: Kyritsis
mesh_terms: D000367:Age Factors; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005909:Glioblastoma / Q000473:pathology / Q000628:therapy*; D006801:Humans; D017567:Karnofsky Performance Status; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D015999:Multivariate Analysis; D011379:Prognosis; D012189:Retrospective Studies; D012737:Sex Factors; D015996:Survival Rate; D000077204:Temozolomide; D016896:Treatment Outcome
chemical_list: D018906:Antineoplastic Agents, Alkylating; D003606:Dacarbazine; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000077204:Temozolomide; C120809:ABCC5 protein, human