title: Association between endometriosis and risk of histological subtypes of ovarian cancer: a pooled analysis of case-control studies.
abstract: BACKGROUND
  Endometriosis is a risk factor for epithelial ovarian cancer; however, whether this risk extends to all invasive histological subtypes or borderline tumours is not clear. We undertook an international collaborative study to assess the association between endometriosis and histological subtypes of ovarian cancer.
  
  
  METHODS
  Data from 13 ovarian cancer case-control studies, which were part of the Ovarian Cancer Association Consortium, were pooled and logistic regression analyses were undertaken to assess the association between self-reported endometriosis and risk of ovarian cancer. Analyses of invasive cases were done with respect to histological subtypes, grade, and stage, and analyses of borderline tumours by histological subtype. Age, ethnic origin, study site, parity, and duration of oral contraceptive use were included in all analytical models.
  
  
  RESULTS
  13 226 controls and 7911 women with invasive ovarian cancer were included in this analysis. 818 and 738, respectively, reported a history of endometriosis. 1907 women with borderline ovarian cancer were also included in the analysis, and 168 of these reported a history of endometriosis. Self-reported endometriosis was associated with a significantly increased risk of clear-cell (136 [20·2%] of 674 cases vs 818 [6·2%] of 13 226 controls, odds ratio 3·05, 95% CI 2·43-3·84, p<0·0001), low-grade serous (31 [9·2%] of 336 cases, 2·11, 1·39-3·20, p<0·0001), and endometrioid invasive ovarian cancers (169 [13·9%] of 1220 cases, 2·04, 1·67-2·48, p<0·0001). No association was noted between endometriosis and risk of mucinous (31 [6·0%] of 516 cases, 1·02, 0·69-1·50, p=0·93) or high-grade serous invasive ovarian cancer (261 [7·1%] of 3659 cases, 1·13, 0·97-1·32, p=0·13), or borderline tumours of either subtype (serous 103 [9·0%] of 1140 cases, 1·20, 0·95-1·52, p=0·12, and mucinous 65 [8·5%] of 767 cases, 1·12, 0·84-1·48, p=0·45).
  
  
  CONCLUSIONS
  Clinicians should be aware of the increased risk of specific subtypes of ovarian cancer in women with endometriosis. Future efforts should focus on understanding the mechanisms that might lead to malignant transformation of endometriosis so as to help identify subsets of women at increased risk of ovarian cancer.
  
  
  BACKGROUND
  Ovarian Cancer Research Fund, National Institutes of Health, California Cancer Research Program, California Department of Health Services, Lon V Smith Foundation, European Community's Seventh Framework Programme, German Federal Ministry of Education and Research of Germany, Programme of Clinical Biomedical Research, German Cancer Research Centre, Eve Appeal, Oak Foundation, UK National Institute of Health Research, National Health and Medical Research Council of Australia, US Army Medical Research and Materiel Command, Cancer Council Tasmania, Cancer Foundation of Western Australia, Mermaid 1, Danish Cancer Society, and Roswell Park Alliance Foundation.
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA. cpearce@usc.edu
authors.forename: Celeste Leigh
authors.initials: CL
authors.lastname: Pearce
authors.forename: Claire
authors.initials: C
authors.lastname: Templeman
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Rossing
authors.forename: Alice
authors.initials: A
authors.lastname: Lee
authors.forename: Aimee M
authors.initials: AM
authors.lastname: Near
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Webb
authors.forename: Christina M
authors.initials: CM
authors.lastname: Nagle
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Doherty
authors.forename: Kara L
authors.initials: KL
authors.lastname: Cushing-Haugen
authors.forename: Kristine G
authors.initials: KG
authors.lastname: Wicklund
authors.forename: Jenny
authors.initials: J
authors.lastname: Chang-Claude
authors.forename: Rebecca
authors.initials: R
authors.lastname: Hein
authors.forename: Galina
authors.initials: G
authors.lastname: Lurie
authors.forename: Lynne R
authors.initials: LR
authors.lastname: Wilkens
authors.forename: Michael E
authors.initials: ME
authors.lastname: Carney
authors.forename: Marc T
authors.initials: MT
authors.lastname: Goodman
authors.forename: Kirsten
authors.initials: K
authors.lastname: Moysich
authors.forename: Susanne K
authors.initials: SK
authors.lastname: Kjaer
authors.forename: Estrid
authors.initials: E
authors.lastname: Hogdall
authors.forename: Allan
authors.initials: A
authors.lastname: Jensen
authors.forename: Ellen L
authors.initials: EL
authors.lastname: Goode
authors.forename: Brooke L
authors.initials: BL
authors.lastname: Fridley
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Larson
authors.forename: Joellen M
authors.initials: JM
authors.lastname: Schildkraut
authors.forename: Rachel T
authors.initials: RT
authors.lastname: Palmieri
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Cramer
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Terry
authors.forename: Allison F
authors.initials: AF
authors.lastname: Vitonis
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Titus
authors.forename: Argyrios
authors.initials: A
authors.lastname: Ziogas
authors.forename: Wendy
authors.initials: W
authors.lastname: Brewster
authors.forename: Hoda
authors.initials: H
authors.lastname: Anton-Culver
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gentry-Maharaj
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Ramus
authors.forename: A Rebecca
authors.initials: AR
authors.lastname: Anderson
authors.forename: Doerthe
authors.initials: D
authors.lastname: Brueggmann
authors.forename: Peter A
authors.initials: PA
authors.lastname: Fasching
authors.forename: Simon A
authors.initials: SA
authors.lastname: Gayther
authors.forename: David G
authors.initials: DG
authors.lastname: Huntsman
authors.forename: Usha
authors.initials: U
authors.lastname: Menon
authors.forename: Roberta B
authors.initials: RB
authors.lastname: Ness
authors.forename: Malcolm C
authors.initials: MC
authors.lastname: Pike
authors.forename: Harvey
authors.initials: H
authors.lastname: Risch
authors.forename: Anna H
authors.initials: AH
authors.lastname: Wu
authors.forename: Andrew
authors.initials: A
authors.lastname: Berchuck
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004715:Endometriosis / Q000150:complications* / Q000453:epidemiology / Q000473:pathology*; D005006:Ethnicity; D005260:Female; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009367:Neoplasm Staging; D010051:Ovarian Neoplasms / Q000150:complications* / Q000453:epidemiology / Q000473:pathology*; D012307:Risk Factors