title: Development and internal validation of a prognostic model for survival after debulking surgery for epithelial ovarian cancer.
abstract: OBJECTIVE
  Predicting survival of patients with epithelial ovarian cancer (EOC) is based on prognosis of the population. Combining prognostic factors could facilitate survival prediction on the level of the individual patient. The aim of this study was to develop a prognostic model to predict five-year disease specific survival in patients with EOC, and to evaluate whether this would add to prediction based on prognosis of the population.
  
  
  METHODS
  A retrospective cohort study was performed of all EOC patients treated with primary debulking and adjuvant chemotherapy or neo-adjuvant chemotherapy and interval debulking surgery in three gynaecological-oncologic centres between 1998 and 2010. Primary outcome was 5-year disease-specific survival. We developed a Cox proportional hazard model using the LASSO-method to select the best combination of characteristics from 12 potential predictors and to correct for overfitting. Performance of the model was expressed as calibration and discrimination (c-statistic). A nomogram was developed to increase the clinical applicability of the model.
  
  
  RESULTS
  Of 840 patients with EOC 462 (55%) died within 5 years due to the disease. A combination of FIGO stage, residual tumour after surgery, primary or interval surgery, histology, performance status, age, amount of ascites and a family history suggestive of breast/ovarian cancer best predicted 5-year survival. The final model showed accurate calibration and the c-statistic was 0.71 (95% CI 0.69-0.74).
  
  
  CONCLUSIONS
  Five-year survival in all stage EOC patients can be predicted accurately using available characteristics. After external validation the model can be used for counselling of patients.
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: m.j.rutten@amc.uva.nl.
authors.forename: M J
authors.initials: MJ
authors.lastname: Rutten
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: J H L
authors.initials: JH
authors.lastname: Boldingh
authors.affiliation: Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands; Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Schuit
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Free University Medical Center, Amsterdam, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Trum
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Anthony van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: van Driel
authors.affiliation: Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: B W J
authors.initials: BW
authors.lastname: Mol
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: G G
authors.initials: GG
authors.lastname: Kenter
authors.affiliation: Centre of Gynaecologic Oncology Amsterdam, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: M R
authors.initials: MR
authors.lastname: Buist
mesh_terms: D000368:Aged; D000077216:Carcinoma, Ovarian Epithelial; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000401:mortality* / Q000601:surgery*; D049451:Nomograms; D010051:Ovarian Neoplasms / Q000401:mortality* / Q000601:surgery*; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate
keywords: Debulking surgery; Nomogram; Ovarian cancer; Prediction; Survival