title: Searching for early breast cancer biomarkers by serum protein profiling of pre-diagnostic serum; a nested case-control study.
abstract: BACKGROUND
  Serum protein profiles have been investigated frequently to discover early biomarkers for breast cancer. So far, these studies used biological samples collected at or after diagnosis. This may limit these studies' value in the search for cancer biomarkers because of the often advanced tumor stage, and consequently risk of reverse causality. We present for the first time pre-diagnostic serum protein profiles in relation to breast cancer, using the Prospect-EPIC (European Prospective Investigation into Cancer and nutrition) cohort.
  
  
  METHODS
  In a nested case-control design we compared 68 women diagnosed with breast cancer within three years after enrollment, with 68 matched controls for differences in serum protein profiles. All samples were analyzed with SELDI-TOF MS (surface enhanced laser desorption/ionization time-of-flight mass spectrometry). In a subset of 20 case-control pairs, the serum proteome was identified and relatively quantified using isobaric Tags for Relative and Absolute Quantification (iTRAQ) and online two-dimensional nano-liquid chromatography coupled with tandem MS (2D-nanoLC-MS/MS).
  
  
  RESULTS
  Two SELDI-TOF MS peaks with m/z 3323 and 8939, which probably represent doubly charged apolipoprotein C-I and C3a des-arginine anaphylatoxin (C3adesArg), were higher in pre-diagnostic breast cancer serum (p = 0.02 and p = 0.06, respectively). With 2D-nanoLC-MS/MS, afamin, apolipoprotein E and isoform 1 of inter-alpha trypsin inhibitor heavy chain H4 (ITIH4) were found to be higher in pre-diagnostic breast cancer (p < 0.05), while alpha-2-macroglobulin and ceruloplasmin were lower (p < 0.05). C3a(desArg) and ITIH4 have previously been related to the presence of symptomatic and/or mammographically detectable breast cancer.
  
  
  CONCLUSIONS
  We show that serum protein profiles are already altered up to three years before breast cancer detection.
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands.
authors.forename: Annemieke W J
authors.initials: AW
authors.lastname: Opstal-van Winden
authors.forename: Esmeralda J M
authors.initials: EJ
authors.lastname: Krop
authors.forename: Monica H
authors.initials: MH
authors.lastname: Kåredal
authors.forename: Marie-Christine W
authors.initials: MC
authors.lastname: Gast
authors.forename: Christian H
authors.initials: CH
authors.lastname: Lindh
authors.forename: Marina C
authors.initials: MC
authors.lastname: Jeppsson
authors.forename: Bo A G
authors.initials: BA
authors.lastname: Jönsson
authors.forename: Diederick E
authors.initials: DE
authors.lastname: Grobbee
authors.forename: Petra H M
authors.initials: PH
authors.lastname: Peeters
authors.forename: Jos H
authors.initials: JH
authors.lastname: Beijnen
authors.forename: Carla H
authors.initials: CH
authors.lastname: van Gils
authors.forename: Roel C H
authors.initials: RC
authors.lastname: Vermeulen
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000175:diagnosis*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D040901:Proteomics; D012307:Risk Factors; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D014408:Biomarkers, Tumor