title: Risk factors for ovarian cancers with and without microsatellite instability.
abstract: OBJECTIVE
  The objective of this study was to evaluate the association between microsatellite instability (MSI) status and (1) ovarian cancer risk factors and (2) the distribution of the specific histologic subtypes in a population-based sample of epithelial ovarian cancers.
  
  
  METHODS
  Participants were drawn from 3 population-based studies of primary epithelial ovarian cancer. Tumor DNA was analyzed using 5 standardized microsatellite markers to assess MSI status. Patients were divided into 3 groups (MSI-high, MSI-low, and MSI-stable) according to National Cancer Institute criteria. We compared the prevalence of specific known risk and protective factors among the 3 subgroups, including body mass index, smoking history, parity, BRCA1 and BRCA2 mutation status, past oral contraceptive use, and tubal ligation. Similarly, we compared the distribution of the histologic subtypes among the 3 subgroups.
  
  
  RESULTS
  A total of 917 ovarian cancer patients were included. One hundred twenty-seven (13.8%) cancers were MSI-high. Subgroup analyses according to smoking, body mass index, parity, past oral contraceptive use, and past tubal ligation did not reveal any statistically significant differences among the groups. Among the 29 patients with BRCA1 mutations, 20.7% had MSI-high cancers compared with 5.9% among 17 BRCA2-mutation patients. The proportions of different ovarian cancer histologic findings among the various MSI subgroups were similar.
  
  
  CONCLUSIONS
  The prevalence of risk and protective factors among ovarian cancer patients is similar for cancers with and without MSI. The distributions of MSI do not differ significantly among ovarian cancers with different histologic findings. Ovarian cancer patients with BRCA1 mutations had a 21% rate of MSI-high tumors, compared with 6% among patients with BRCA2 mutations, but this difference was not statistically significant.
authors.affiliation: Familial Breast Cancer Research, Women's College Research Institute, Toronto, Ontario, Canada.
authors.forename: Yakir
authors.initials: Y
authors.lastname: Segev
authors.forename: Tuya
authors.initials: T
authors.lastname: Pal
authors.forename: Barry
authors.initials: B
authors.lastname: Rosen
authors.forename: John R
authors.initials: JR
authors.lastname: McLaughlin
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Sellers
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Risch
authors.forename: Shiyu
authors.initials: S
authors.lastname: Zhang
authors.forename: Sun
authors.initials: S
authors.lastname: Ping
authors.forename: Steven A
authors.initials: SA
authors.lastname: Narod
authors.forename: Joellen
authors.initials: J
authors.lastname: Schildkraut
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D002288:Adenocarcinoma, Mucinous / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D002170:Canada / Q000453:epidemiology; D002291:Carcinoma, Papillary / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D015331:Cohort Studies; D018284:Cystadenocarcinoma, Serous / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D016889:Endometrial Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053842:Microsatellite Instability; D008875:Middle Aged; D009367:Neoplasm Staging; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D011379:Prognosis; D012307:Risk Factors; D014481:United States / Q000453:epidemiology