The usefulness of prostate-specific antigen (PSA) density in patients with intermediate serum PSA level in a country with low incidence of prostate cancer.

OBJECTIVES

To evaluate if a calculated PSA density (PSAD) prior to biopsy could be useful to determine the need for prostate biopsies in patients with serum PSA levels of 4.1-20.0 ng/mL in a country with low incidence of prostate cancer (PCa).

METHODS

A total of 185 consecutive patients aged 50-79 years who underwent prostate biopsies were evaluated by correlating the biopsy results with the results of digital rectal examination (DRE), transrectal ultrasonography (TRUS), serum PSA levels, and PSAD. Prostate volume was calculated from TRUS using prolate ellipse formula and PSAD was obtained by dividing serum PSA level by prostate volume.

RESULTS

In this study population, 27 cases (14.6%) had positive biopsies. Of 158 cases with negative biopsies, 43 (23.2%) had histologically verified prostatic inflammation. The diagnostic value of DRE and TRUS was hampered by unsatisfactory sensitivity and specificity in differentiating patients with positive biopsies from those with negative biopsies. The use of PSAD alone as an indicator for biopsy was also limited by its low specificity. A PSAD cutoff value of 0.15 resulted in a sensitivity of 100% and a specificity of only 12%. Prostatic inflammation was a confounding factor for the inadequate specificity of DRE, TRUS and PSAD. Combined use of DRE and PSAD provided the best information regarding the need for biopsies. Accordingly, if the 47 patients (25.4%) who presented with both a negative DRE and a PSAD < or = 0.20 were not biopsied, the rate of positive biopsy could have increased to 19.6% (27 of 138) without missing any cancer detection.

CONCLUSIONS

It is concluded from this study that for patients with serum PSA levels of 4.1-20.0 ng/mL, biopsies should only be recommended for those with abnormal DRE and/or PSAD >0.20.