title: Impact of the menstrual cycle on circulating cell-free DNA.
abstract: BACKGROUND
  To determine serum levels of circulating cell-free DNA (cfDNA) throughout the stages of endometrial proliferation and apoptosis during the menstrual cycle.
  
  
  METHODS
  cfDNA was measured in 176 blood samples from 17 healthy volunteers taken at three different time points (menstruation, follicular and secretory phase). Additionally, blood samples from 20 newly diagnosed breast cancer patients were analysed. Quantitative real-time PCR was performed in order to quantify cfDNA fragments of 106 bp.
  
  
  RESULTS
  In healthy individuals, levels of cfDNA did not differ significantly during the menstrual cycle. In breast cancer patients, the median cfDNA level was significantly higher compared to healthy individuals, irrespective of the cycle phase (p<0.001).
  
  
  CONCLUSIONS
  The female cycle does not influence cfDNA serum level measurements. Considering the diagnostic or prognostic value of cfDNA in cancer patients, different time points of blood sampling in premenopausal women seem to be negligible.
authors.affiliation: Department of Gynecology and Obstetrics, Center for Integrated Oncology, Bonn University Medical Center, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany. martin.poelcher@ukb.uni-bonn.de
authors.forename: Martin
authors.initials: M
authors.lastname: Pölcher
authors.forename: Jörg
authors.initials: J
authors.lastname: Ellinger
authors.forename: Stephanie
authors.initials: S
authors.lastname: Willems
authors.forename: Osman
authors.initials: O
authors.lastname: El-Maarri
authors.forename: Tobias
authors.initials: T
authors.lastname: Höller
authors.forename: Charlotte
authors.initials: C
authors.lastname: Amann
authors.forename: Matthias
authors.initials: M
authors.lastname: Wolfgarten
authors.forename: Christian
authors.initials: C
authors.lastname: Rudlowski
authors.forename: Walther
authors.initials: W
authors.lastname: Kuhn
authors.forename: Michael
authors.initials: M
authors.lastname: Braun
mesh_terms: D000328:Adult; D015415:Biomarkers; D001943:Breast Neoplasms / Q000097:blood*; D004247:DNA / Q000097:blood*; D005260:Female; D006801:Humans; D008597:Menstrual Cycle
chemical_list: D015415:Biomarkers; D004247:DNA