title: Defining the optimal lymphadenectomy cut-off value in epithelial ovarian cancer staging surgery utilizing a mathematical model of validation.
abstract: OBJECTIVE
  Since 1985 International Federation of Gynecology and Obstetrics includes pelvic and aortic lymphadenectomy as part of the surgical staging in epithelial ovarian cancer (EOC). There is no consensus on the overall number of nodes needed in a systematic lymphadenectomy. The aim of this study is to calculate the optimal cut-off value using a mathematical modeling approach.
  
  
  METHODS
  Data was collected retrospectively, from 1996 to 2000, of 120 consecutive Mayo Clinic patients with EOC and positive nodes. All patients was underwent pelvic and/or aortic lymphadnectomy during surgical staging. To mathematically predict the probability of a positive node in EOC patients we used a predictive mathematical model (PMM). The mathematical analysis consisted: creation of a new PMM according to our purposes, application of PMM to describe the experimental data in order to build the polynomial regression curves in each lymphatic area and determine the optimal point for each curve.
  
  
  RESULTS
  The mean number of lymph nodes and metastatic nodes removed were 35 and 7.8, respectively; the mean percentage of positive nodes was 28.3%. The optimal point of each fitting curves were: 7 nodes for unilateral aortic nodal sampling (at least 3 infrarenal or 5 inframesenteric) and 15 nodes for unilateral pelvic lymphadenectomy (at least 5 external iliac).
  
  
  CONCLUSIONS
  We can mathematically predict the probability to obtain a positive node in EOC surgical staging. Our results have shown the need to obtain at least 22 lymph nodes between pelvic and aortic lymphadenectomy.
authors.affiliation: Department of Gynecologic Surgery, Puerta de Hierro University Hospital of Madrid, Joaquin Rodrigo, 2, Madrid 28 222, Spain. apereiras@sego.es
authors.forename: A
authors.initials: A
authors.lastname: Pereira
authors.forename: N
authors.initials: N
authors.lastname: Irishina
authors.forename: T
authors.initials: T
authors.lastname: Pérez-Medina
authors.forename: J F
authors.initials: JF
authors.lastname: Magrina
authors.forename: P M
authors.initials: PM
authors.lastname: Magtibay
authors.forename: A
authors.initials: A
authors.lastname: Kovaleva
authors.forename: A
authors.initials: A
authors.lastname: Rodríguez-Tapia
authors.forename: E
authors.initials: E
authors.lastname: Iglesias
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta; D000077216:Carcinoma, Ovarian Epithelial; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods* / Q000592:standards; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery*; D008207:Lymphatic Metastasis / Q000175:diagnosis; D008875:Middle Aged; D008962:Models, Theoretical; D009375:Neoplasms, Glandular and Epithelial / Q000473:pathology* / Q000601:surgery*; D010051:Ovarian Neoplasms / Q000473:pathology* / Q000601:surgery*; D010388:Pelvis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies