title: Characteristics of clear cell ovarian cancer arising from endometriosis: a two center cohort study.
abstract: OBJECTIVE
  Endometrioid and clear cell ovarian tumors have been referred to as "endometriosis associated ovarian cancers". However, very few studies have compared clinical and prognostic features of endometriosis-associated cancers or cancers not associated with endometriosis according to specific histotypes. We have investigated clinical and histological features of the largest published series of clear cell ovarian cancers arising in endometriosis using a retrospective database.
  
  
  METHODS
  Seventy three patients with a primary diagnosis of either pure clear cell ovarian cancer and mixed endometrioid-clear cell ovarian cancer have been divided into two groups according to the detection of cancer strictly arising from ovarian endometriosis or not (n=27 and n=46, respectively). Clinical and pathological data have been compared.
  
  
  RESULTS
  Patients with clear cell carcinomas arising from endometriosis tend to be significantly younger (51.4±10.0 and 58.4±11.2years, p=0.02). FIGO stage, laterality, prevalence of pure versus mixed histology, and presence of synchronous endometrial carcinoma were not significantly different between the two groups. Unilateral ovarian involvement was more frequent in cases arising in endometriosis (85% vs 63%, p=0.04). Ascites was not found in any of the endometriosis-associated cancer cases vs 19.5% in patients without endometriosis. The presence of endometriosis did not affect 5-year overall survival rates.
  
  
  CONCLUSIONS
  Endometriosis per se does not appear to be associated with a lower stage tumor or to predict prognosis in ovarian clear cell cancers. Unilateral involvement and reduced presence of ascites may be linked to the cystic nature of endometriosis which frequently presents as monolateral and in which associated tumors are more likely to be longer confined to the ovary before spreading.
authors.affiliation: Department of Obstetrics, Gynecology and Neonatology, IRCCS Fondazione Cà Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Scarfone
authors.affiliation: Università Vita-Salute, San Raffale Scientific Institute, Milano, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Bergamini
authors.affiliation: Department of Obstetrics, Gynecology and Neonatology, IRCCS Fondazione Cà Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Noli
authors.affiliation: Department of Obstetrics, Gynecology and Neonatology, IRCCS Fondazione Cà Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Villa
authors.affiliation: Mario Negri Pharmacological Research Institute, Milan, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Cipriani
authors.affiliation: Department of Surgical Pathology, San Raffaele Scientific Institute, Milano, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Taccagni
authors.affiliation: Obstetrics and Gynecology Unit, San Raffaele Scientific Institute, Milano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Vigano'
authors.affiliation: Università Vita-Salute, San Raffale Scientific Institute, Milano, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Candiani
authors.affiliation: Mario Negri Pharmacological Research Institute, Milan, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Parazzini
authors.affiliation: Obstetrics and Gynecology Unit, San Raffaele Scientific Institute, Milano, Italy. Electronic address: mangili.giorgia@hsr.it.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Mangili
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D018269:Carcinoma, Endometrioid / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D016022:Case-Control Studies; D015331:Cohort Studies; D004715:Endometriosis / Q000150:complications*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies
keywords: Clear cell ovarian cancer; Endometriosis; Endometriosis associated ovarian cancer