Should prostate-specific antigen or prostate-specific antigen density be used as the determining factor when deciding which prostates should undergo biopsy during prostate ultrasound.

Abstract

Prostate ultrasound has been accepted as the appropriate tool for prostate biopsy guidance to determine the presence of prostate cancer if the prostate-specific antigen (PSA) level is not normal. Prostate-specific antigen density (PSAD) has been used to determine if an increased PSA level may be because of benign enlargement of the gland or possible presence of cancer. The specific "cutoff" for PSA and PSAD to delineate which patients are at highest risk has been controversial. We attempted to assess which PSA level or PSAD level should be used. A retrospective analysis of 600 consecutive men, referred for prostate ultrasound and possible biopsy because of an abnormal DRE result or increased PSA level was undertaken. All had prostate volume determined by biplanar endorectal ultrasound. One hundred sixty-six men had cancer confirmed by biopsy. This latter group was further analyzed and was divided into PSA <4.0, PSA 4 to 10, or PSA >10.0 ng/ml. Groups were divided according to those with PSAD <0.10, <0.12, and <0.15 ng/ml. Correlation with Gleason grade of the tumor was made. Of the 166 men with cancer, 15 had PSA levels <4 ng/ml (all palpable), and 81 had PSA levels between 4.0 and 10.0 ng/ml (48 were not palpable by digital rectal examination [DRE]). There were 38 (22.8%) of 166 men with cancer who had a PSAD <0.15. Using the Gleason scoring system, 30 of 38 men had mid-grade or high-grade cancers. Twenty-one (12.6%) of 166 men with cancer had a PSAD <0.12. Of these, 17 of 21 men had mid-grade or high-grade cancers. Fifteen (9.0%) of 166 men with cancer had a PSAD <0.10. Of these, 13 of 15 had mid-grade or high-grade cancer. If the PSA level is more than 4.0 ng/ml, even if no palpable lesion is discerned by DRE, suspicion for the presence of cancer should be raised. The use of PSAD threshold of 0.15 is not inclusive enough to identify clinically important cancer, and it should not be used. Our data demonstrate that 7.9% of men with cancer had a PSAD <0.15 and mid-grade or high-grade, i.e., clinically important, cancer. Although more negative biopsy results will be obtained, we recommend the use of a lower PSAD "cutoff" than the literature has suggested. We recommend that those men with PSA levels more than 4 ng/ml and a PSAD higher than 0.10 should undergo a prostate biopsy to detect clinically important cancer.