title: Extended use of P504S positive primary circulating prostate cell detection to determine the need for initial prostate biopsy in a prostate cancer screening program in Chile.
abstract: BACKGROUND
  To determine the frequency of primary circulating prostate cells (CPC) detection according to age and serum PSA levels in a cohort of men undergoing screening for prostate cancer and to determine the diagnostic yield in those men complying with the criteria for prostate biopsy.
  
  
  METHODS
  A prospective study was carried out to analyze all men evaluated in a hospital prostate cancer screening program. Primary CPCs were obtained by differential gel centrifugation and detected using standard immunocytochemistry using anti-PSA, positive samples undergoing a second process with anti-P504S. A malignant primary CPC was defined as PSA+ P504S+, and a test positive if 1 cell/4ml was detected. The frequency of primary CPC detection was compared with age and serum PSA levels. Men with a PSA >4.0ng/ml and/or abnormal rectal examination underwent 12 core prostate biopsy, and the results were registered as cancer/no-cancer and compared with the presence/absence of primary CPCs to calculate the diagnostic yield.
  
  
  RESULTS
  A total of 1,117 men participated; there was an association of primary CPC detection with increasing age and increasing serum PSA. Some 559 men underwent initial prostate biopsy of whom 207/559 (37.0%) were positive for primary CPCs and 183/559 (32.0%) had prostate cancer detected. The diagnostic yield of primary CPCs had a sensitivity of 88.5%, a specificity of 88.0%, and positive and negative predictive values of 78.3% and 94.9%, respectively.
  
  
  CONCLUSIONS
  The use of primary CPCs for testing is recommended, since its high negative predictive value could be used to avoid prostate biopsy in men with an elevated PSA and/or abnormal DRE. Men positive for primary CPCs should undergo prostate biopsy. It is a test that could be implemented in the routine immunocytochemical laboratory.
authors.affiliation: Hospital Carabineros of Chile, Nunoa, Chile E-mail : nigelpetermurray@gmail.como.
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Murray
authors.forename: Eduardo
authors.initials: E
authors.lastname: Reyes
authors.forename: Cynthia
authors.initials: C
authors.lastname: Fuentealba
authors.forename: Omar
authors.initials: O
authors.lastname: Jacob
authors.forename: Nelson
authors.initials: N
authors.lastname: Orellana
mesh_terms: D000367:Age Factors; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D001707:Biopsy, Needle; D016009:Chi-Square Distribution; D002677:Chile; D015331:Cohort Studies; D016001:Confidence Intervals; D055088:Early Detection of Cancer / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000378:metabolism / Q000473:pathology*; D010865:Pilot Projects; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000473:pathology*; D019998:Racemases and Epimerases / Q000235:genetics / Q000378:metabolism*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase