Extended use of P504S positive primary circulating prostate cell detection to determine the need for initial prostate...

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.

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.

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.

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.