title: The prognostic value of dividing epithelial ovarian cancer into type I and type II tumors based on pathologic characteristics.
abstract: OBJECTIVE
  To investigate the prognostic significance of dividing epithelial ovarian cancer (EOC) in type I and type II tumors based on pathologic variables.
  
  
  METHODS
  We used the Danish Gynecologic Cancer Database to identify all patients diagnosed with EOC from 2005 to 2012. Information on histologic type and grade were used to classify tumors as either type I or type II. Death, and several prognostic factors were used in the multivariate Cox regression, and Landmark analysis was used to estimate hazard ratios of all-cause mortality.
  
  
  RESULTS
  Among 2660 patients diagnosed with EOC, 735 were categorized as type I tumors, and 1925 as type II tumors. Patients with type II EOC were more frequently diagnosed in late FIGO stages (stages III-IV) than patients with type I EOC (78.1% vs. 32.1% respectively; P<0.001). Time dependent multivariate Cox analysis, adjusted for known prognostic variables, showed no significant difference in survival within the first two years after diagnosis, however, after 730days of follow-up a significantly increased overall survival for type I tumors was observed (hazard ratio 1.72, 95% confidence interval: 1.28-2.31, P<0.001). Similarly the Landmark analysis for survival confirmed the increased overall survival for type I tumors after two years of follow-up (hazard ratio: 1.85, 95% confidence interval: 1.35-2.54, P<0.001).
  
  
  CONCLUSIONS
  Classification of EOC in type I and type II tumors based on pathologic variables was associated with an increased risk of death for type II tumors after two years of follow-up, while no increased risk was seen during the first two years of follow-up.
authors.affiliation: Dept. of Gynecology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. Electronic address: kira@prahm.dk.
authors.forename: Kira Philipsen
authors.initials: KP
authors.lastname: Prahm
authors.affiliation: Molecular Unit, Dept. of Pathology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mona Aarenstrup
authors.initials: MA
authors.lastname: Karlsen
authors.affiliation: Molecular Unit, Dept. of Pathology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Estrid
authors.initials: E
authors.lastname: Høgdall
authors.affiliation: Dept. of Epidemiologic Research, Statens Serum Institute, Copenhagen, Denmark.
authors.forename: Nikolai Madrid
authors.initials: NM
authors.lastname: Scheller
authors.affiliation: Dept. of Gynecology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Lundvall
authors.affiliation: Dept. of Pathology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lotte
authors.initials: L
authors.lastname: Nedergaard
authors.affiliation: Finsen Laboratory, Copenhagen Biocenter, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ib Jarle
authors.initials: IJ
authors.lastname: Christensen
authors.affiliation: Dept. of Gynecology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Claus
authors.initials: C
authors.lastname: Høgdall
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000077216:Carcinoma, Ovarian Epithelial; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000145:classification* / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000145:classification* / Q000473:pathology*; D011379:Prognosis; D016019:Survival Analysis
keywords: Epithelial ovarian cancer; Pathologic characteristics; Prognostic value; Type I and type II