title: The relation between endometriosis and ovarian cancer - a review.
abstract: BACKGROUND
  Endometriosis is known to harbor characteristics substantiating its possible role as a precursor of ovarian cancer.
  
  
  OBJECTIVE
  To assess the quality of the literature regarding the association between endometriosis and ovarian cancer and to estimate the extent of this relation.
  
  
  METHODS
  An electronic literature search was conducted in PubMed and 1112 articles dealing with the relation between endometriosis and ovarian cancer were identified. Original articles based on case-control studies, cohort studies and cross-sectional studies were included. Studies consisting of populations with self-reported endometriosis were excluded, as were articles with fewer than 20 cases of ovarian cancer. Twenty-eight studies underwent detailed quality assessments based on the checklists developed by the Scottish Intercollegiate Guidelines Network (SIGN). Meta-analyses were conducted on selected subgroups of ovarian cancer with coexisting endometriosis.
  
  
  RESULTS
  None of the 28 studies was given the highest possible rating using the SIGN checklists. The risk of ovarian cancer in women with endometriosis was reported to be a standardized incidence ratio of 1.43-8.95, a rate ratio of 1.6-2.88, an odds ratio of 1.34, with a prevalence of ovarian cancer in 2.0-17.0% of women with endometriosis. Conversely, the prevalence of endometriosis in women with ovarian cancer ranged from 3.4 to 52.6%. Meta-analysis results were weakened by heterogeneity.
  
  
  CONCLUSIONS
  There is sufficient evidence to conclude that there is an increased risk of developing clear-cell and endometrioid epithelial ovarian cancer for women with histologically verified endometriosis. Nonetheless, prospective cohort studies assessing the relation between endometriosis and ovarian cancer will increase knowledge in this field.
authors.affiliation: Department of Obstetrics and Gynecology, Odense University Hospital, Odense, Denmark.
authors.forename: Lene N
authors.initials: LN
authors.lastname: Heidemann
authors.forename: Dorthe
authors.initials: D
authors.lastname: Hartwell
authors.forename: Christian H
authors.initials: CH
authors.lastname: Heidemann
authors.forename: Kirsten M
authors.initials: KM
authors.lastname: Jochumsen
mesh_terms: D004715:Endometriosis / Q000150:complications* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D015995:Prevalence; D012306:Risk
keywords: Endometriosis; meta-analysis; ovarian cancer; review; risk