Background: Combining risk factors for prostate cancer into a predictive tool may improve the detection ofprostate cancer while decreasing the number of benign biopsies. We compare one such tool, age multiplied byprostate volume divided by total serum PSA (PSA-AV) with PSA density and detection of primary malignantcirculating prostate cells (CPCs) in a Chilean prostate cancer screening program. The objectives were not only todetermine the predictive values of each, but to determine the number of clinically significant cancers that wouldhave been detected or missed. Materials and
Methods: A prospective study was conducted of all men undergoing12 core ultrasound guided prostate biopsy for suspicion of cancer attending the Hospital DIPRECA and Hospitalde Carabineros de Chile. Total serum PSA was registered, prostate volumecalculated at the moment of biopsy,and an 8ml blood simple taken immediately before the biopsy procedure. Mononuclear cells were obtained fromthe blood simple using differential gel centrifugation and CPCs identified using immunocytchemistry with anti-PSA and anti-P504S. Biopsy results were classed as positive or negative for cancer and if positive the Gleasonscore, number of positive cores and percent infiltration recorded.
Results: A total of 664 men participated, ofwhom 234 (35.2%) had cancer detected. They were older, had higher mean PSA, PSA density and lower PSA-AV.Detection of CPCs had high predictive score, sensitivity, sensibility and positive and negative predictive values,PSA-AV was not significantly different from PSA density in this population. The use of CPC detection avoidedmore biopsies and missed fewer significant cancers.
Conclusions: In this screening population the use of CPCdetection predicted the presence of clinically significant prostate cancer better than the other parameters. Thehigh negative predictive value would allow men CPC negative to avoid biopsy but remain in follow up. Theformula PSA-AV did not add to the predictive performance using PSA density.