[Parameters to improve the specificity of the prostate-specific antigen. Early detection of prostate cancer]

The aim of the study was to improve the case detection rate of prostate cancer for patients who had unremarkable palpation findings and a PSA value in the range of 4 to 10 ng/ml by combination of the parameters total PSA (tPSA), f/tPSA ratio, prostate volume, PSA density, patient's age and transrectal ultrasound findings.

Sextant biopsy of the prostate was performed for 619 patients aged 45-75 years who had unremarkable palpation findings and PSA values in the range of 4 to 10 ng/ml. The f/tPSA ratio was determined, transrectal ultrasound examination was performed, the prostate volume was measured and the PSA density calculated. The relationship between the various test variables - and their combination - and the histology results was investigated using logistic regression.

Prostate cancer was detected in 131 of 619 patients. Analysis of the aforementioned test variables by means of logistic regression revealed that the combination of the parameters f/tPSA ratio, PSA density and patient's age can significantly increase the sensitivity and specificity of PSA in predicting prostate cancer compared with the use of these parameters on an individual basis. With an assumed limit value of 5% for performance of punch biopsy, 31% of biopsies could be avoided in practice. In such a case, only 3% of instances of prostate cancer would have gone undetected.

The combined use of f/tPSA ratio, PSA density and patient's age can significantly enhance the case detection sensitivity for the PSA range of 4 to 10 ng/ml.