title: Case-controlled identification of colorectal cancer based on proteomic profiles and the potential for screening.
abstract: OBJECTIVE
  Colorectal cancer (CRC) screening programmes detect early cancers but unfortunately have limited sensitivity and specificity. Mass spectrometry-based determination of serum peptide and protein profiles provides a new approach for improved screening.
  
  
  METHODS
  Serum samples were obtained from 126 CRC patients before treatment and 277 control individuals. An additional group of samples from 50 CRC patients and 82 controls was used for validation. Peptide and protein enrichments were carried out using reverse-phase C18 and weak-cation exchange magnetic beads in an automated solid-phase extraction and spotting procedure. Profiles were acquired on a matrix-assisted laser desorption/ionization time-of-flight system. Discriminant rules using logistic regression were calibrated for the peptide and protein signatures separately, followed by combining the classifications to obtain double cross-validated predicted class probabilities. Results were validated on an identical patient set.
  
  
  RESULTS
  A discriminative power was found for patients with CRC representative for all histopathological stages compared with controls with an area under the curve of 0.95 in the test set (0.93 for the validation set) and with a high specificity (94-95%).
  
  
  CONCLUSIONS
  The study has shown that a serum peptide and protein biomarker signature can be used to distinguish CRC patients from healthy controls with high discriminative power. This relatively simple and cheap test is promising for CRC screening.
authors.affiliation: Department of Surgery, Leiden Universal Medical Center, Leiden, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Huijbers
authors.forename: W E
authors.initials: WE
authors.lastname: Mesker
authors.forename: B J
authors.initials: BJ
authors.lastname: Mertens
authors.forename: M R
authors.initials: MR
authors.lastname: Bladergroen
authors.forename: A M
authors.initials: AM
authors.lastname: Deelder
authors.forename: Y E M
authors.initials: YE
authors.lastname: van der Burgt
authors.forename: R A E M
authors.initials: RA
authors.lastname: Tollenaar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000097:blood / Q000175:diagnosis*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D040901:Proteomics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D014408:Biomarkers, Tumor
keywords: Colorectal cancer; MALDI-TOF; early detection; proteomics; screening