title: Low-grade oligodendroglioma: an indolent but incurable disease? Clinical article.
abstract: OBJECTIVE
  The authors reviewed their institutional experience with pure low-grade oligodendroglioma (LGO), correlating outcomes with several variables of possible prognostic values.
  
  
  METHODS
  Sixty-nine patients with WHO-classified LGOs were treated between 1992 and 2006 at the McGill University Health Center. Clinical, pathological, and radiological records were carefully reviewed. Demographic characteristics; the nature and duration of presenting symptoms; baseline neurological function; extent of resection; Karnofsky Performance Scale score; preoperative radiological findings including tumor size, location, and absence/presence of enhancement; and pathological data including chromosome arms 1p/19q codeletion and O-methylguanine-DNA methyltransferase promoter gene methylation status were all compiled. The timing and dose of radio- and/or chemotherapy, date of tumor progression, pathological finding at disease progression, treatment at time of disease progression, and status at the last follow-up were also recorded.
  
  
  RESULTS
  The median follow-up period was 6.1 years (range 1.3-16.3 years). The majority (78%) of patients presented with seizures; contrast enhancement was initially seen in 16 patients (25%). All patients had undergone an initial surgical procedure: gross-total resection in 27%, partial resection in 59%, and biopsy only in the remaining 13%. Fifteen patients received adjuvant radiotherapy. Data on O-methylguanine-DNA methyltransferase promoter gene methylation status was available in 47 patients (68%) and in all but 1 patient for 1p/19q status. Survival at 5, 10, and 15 years was 83, 63, and 29%, respectively. Multivariate analysis showed that seizures at presentation and the absence of contrast enhancement were the only independent favorable prognostic factors for survival. The 5-, 10-, and 15-year progression-free survival rates were 46, 7.7, and 0%, respectively.
  
  
  CONCLUSIONS
  This retrospective review confirms the indolent but progressively fatal nature of LGOs. Contrast enhancement was the most evident single prognostic factor. New treatment strategies are clearly needed in the management of this disease.
authors.affiliation: Department of Radiation Oncology, McGill University Health Center, Montreal, Quebec, Canada.
authors.forename: Hamdy
authors.initials: H
authors.lastname: El-Hateer
authors.forename: Luis
authors.initials: L
authors.lastname: Souhami
authors.forename: David
authors.initials: D
authors.lastname: Roberge
authors.forename: Rolando Del
authors.initials: RD
authors.lastname: Maestro
authors.forename: Richard
authors.initials: R
authors.lastname: Leblanc
authors.forename: Eman
authors.initials: E
authors.lastname: Eldebawy
authors.forename: Thierry
authors.initials: T
authors.lastname: Muanza
authors.forename: Denis
authors.initials: D
authors.lastname: Melançon
authors.forename: Petr
authors.initials: P
authors.lastname: Kavan
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Guiot
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017567:Karnofsky Performance Status; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000000981:diagnostic imaging / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D011379:Prognosis; D011859:Radiography; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies