Introduction: At least nine different manufacturers currently produce at least 14 different methods for measuring total PSA. The number of available methods of measuring the free to total ratio of PSA (f/tPSA) is in turn rapidly expanding. Patients and methods: The f/tPSA was measured in 103 men aged over 50 years immediately before guided sextant prostatic biopsy and the serum f/tPSA compared using four available immunofluorometric assays (Chiron ACS 180. Wallac Déifia Prostatus. Hybritech Tandem-R and DPC Immulite). Results: There were no significant differences between the Déifia Prostatus and Hybritech Tandem-R or between the DPC Immulite and ACS 180 methods in the 71 patients found histologically to have cancer, or the 32 found to have benign prostatic disease. However, there was a highly significant difference between the results of the Déifia Prostatus and both the Chiron ACS 180 and Immulite methods for both benign disease (P< 0.001) and cancer (P < 0.001 ). Differences were also significant between the Hybritech Tandem-R and the Chiron ACS 180 methods (benign; P< 0.02; malignant P < 0.007) and between the Hybritech Tandem-R and DPC Immulite assays for malignant disease only (P< 0.001). There was a significant difference between the last two methods for benign disease (P < 0.05). The accuracy of cancer prediction also varied with the method and threshold selected. There was a correlation between Gleason grade and f/tPSA. Conclusions: With the rapid expansion of f/tPSA testing, we would advise caution in interpreting the results of this measurement and in particular suggest that the details of the method used to obtain the result are reported.
|Number of pages||1|
|Journal||British Journal of Urology|
|Issue number||SUPPL. 4|
|Publication status||Published - 1998|