Impact of total PSA and percent free PSA in the differentiation of prostate disease: a retrospective comparative study implicating neoplastic and non-neoplastic entities.

PURPOSE: To evaluate the potential of prostate cancer detection on the basis of prostate-specific antigen (PSA)-level and percent free PSA (% fPSA) according to the outcome of prostate needle biopsy.

METHODS

This was a retrospective study of 1040 patients that underwent a prostate biopsy in the Urologic Clinic of the University Hospital of Ioannina, Greece. The patients underwent needle biopsy after abnormal finding in digital rectal examination (DRE). Tissue samples were extracted using a 12-core TRUS-GB. The patients were divided into four groups according to the biopsy outcome. Total serum and free PSA were measured.

RESULTS

The mean PSA concentration of cancer versus noncancer groups was significantly higher (p<0.05). The positive predictive value (PPV) of PSA for serum concentration >10 ng/ml was 47% while the negative predictive value (NPV) in patients with PSA levels <4 ng/ml was 81%. The diagnostic accuracy of % fPSA for patients with PSA level between 4-10 ng/ml was 0.651 (95% CI, 0.549-0.754) (p<0.05). A statistically significant difference in mean PSA concentration was recorded between prostate cancers classified as grade 2 (3+4=7) and 3 (4+3=7) and grade 4 (8) and 5 (9-10) (p<0.05).

CONCLUSIONS

Though informative and suggestive, PSA and % fPSA are not definitive for cancer or non-cancer determination. The differentiation of PSA level between tumours classified as grade 2 (3+4=7) and grade 3 (4+3=7) could support the determination of treatment by backing pathologist's interpretation of the histological diagnosis.