title: Endometriosis and the subsequent risk of epithelial ovarian cancer.
abstract: OBJECTIVE
  There is a possible correlation between endometriosis and an increased risk of epithelial ovarian cancer (EOC), but many uncertainties remain, including race, exposure or surveillance time, and surgical confirmation. Therefore, we carried out a large-scale, nationwide, controlled cohort study in the Taiwanese women to respond to these uncertainties.
  
  
  METHODS
  A historical cohort study was performed by linking the National Health Insurance Research Database of Taiwan. Each patient diagnosed with endometriosis (n = 7537) between 2000 and 2009 was background matched with up to two women without endometriosis (n = 15,074). The total was 136,643 person-years of follow-up and 24 women having new EOC. Cox regression analysis was used to determine the relationship between the EOC incidence rate and an endometriosis status.
  
  
  RESULTS
  The EOC incidence rate of the endometriosis and non-endometriosis women was 3.31 per 10,000 person-years and 0.99 per 10,000 person-years, respectively, contributing to an adjusted hazard ratio (HR) of 3.28 (95% confidence interval, 1.37-7.85). The women with surgical confirmation had a much higher adjusted HR (3.87; 95% confidence interval, 1.58-9.47). No significantly statistical difference of surveillance time between women with and without endometriosis (3.87 years vs. 3.73 years). The occurrence of EOC was not also affected by exposure time of women with endometriosis.
  
  
  CONCLUSIONS
  Taiwanese women with endometriosis really had a risk of newly developed EOC, especially those who had a surgical diagnosis, and this three-fold increase of risk was neither influenced by exposure time nor biased by surveillance.
authors.affiliation: Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Nursing, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Nursing, National Yang-Ming University, Taipei, Taiwan; Institute of Hospital and Health Care Administration and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Hsun
authors.initials: WH
authors.lastname: Chang
authors.affiliation: Department of Nursing, Oriental Institute of Technology, New Taipei City, Taiwan.
authors.forename: Kuan-Chin
authors.initials: KC
authors.lastname: Wang
authors.affiliation: Department of Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Nursing, Oriental Institute of Technology, New Taipei City, Taiwan; Department of Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan.
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Lee
authors.affiliation: Institute of Hospital and Health Care Administration and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Nicole
authors.initials: N
authors.lastname: Huang
authors.affiliation: Institute of Hospital and Health Care Administration and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yiing-Jeng
authors.initials: YJ
authors.lastname: Chou
authors.affiliation: Department of Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Nursing, Taipei City Hospital, Taipei, Taiwan.
authors.forename: Rung-Chuang
authors.initials: RC
authors.lastname: Feng
authors.affiliation: Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ming-Shyen
authors.initials: MS
authors.lastname: Yen
authors.affiliation: Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University Hospital, Ilan, Taiwan.
authors.forename: Ben-Shian
authors.initials: BS
authors.lastname: Huang
authors.affiliation: Institute of Hospital and Health Care Administration and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan. Electronic address: cyguo@ym.edu.tw.
authors.forename: Chao-Yu
authors.initials: CY
authors.lastname: Guo
authors.affiliation: Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University Hospital, Ilan, Taiwan; Immunology Center, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung, Taiwan. Electronic address: phwang@vghtpe.gov.tw.
authors.forename: Peng-Hui
authors.initials: PH
authors.lastname: Wang
mesh_terms: D000328:Adult; D000077216:Carcinoma, Ovarian Epithelial; D016022:Case-Control Studies; D015331:Cohort Studies; D016208:Databases, Factual; D004715:Endometriosis / Q000150:complications*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000453:epidemiology / Q000209:etiology*; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000209:etiology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan
keywords: Cohort study; Endometriosis; Epithelial ovarian cancer; Risk; Surgical diagnosis