Background: The objectives of this study were to compare the efficacy of 3 modalities (prostate-specific antigen (PSA) assay, digital rectal examination (DRE), and transrectal ultrasonography (TRUS)) in detecting prostate cancer which was pathologically confirmed by TRUS-guided systematic six-sextant biopsy, and to investigate the relationship between the number of positive cores and several clinicopathological parameters.

Methods: Between 1992 and 1994, 297 males (155 from a mass screening program and 142 identified as outpatients) with a mean age of 71 years, underwent examinations including PSA determination, DRE, TRUS and systematic six-sextant biopsy, and/or additional directed biopsy.

Results: Prostate cancer was detected in 93 men. The sensitivity level of the PSA assay was significantly higher (85%) than that of either DRE or TRUS. Patients with an abnormal DRE or TRUS, elevated PSA levels, and those in the T3-T4 category or with moderate to poorly-differentiated adenocarcinomas had more positive biopsy cores (P < 0.05). Also, the relationships of both the number of positive biopsy cores and tumor grade to bone metastasis were significant (P < 0.01). Of 209 hypoechoic areas identified by transrectal ultrasonography, 42% were cancerous, and of 427 isoechoic areas, 12% were cancerous. The percentage of positive biopsy cores with hypoechoic areas was 86% in the subjects with a PSA > 10 ng/mL, but low (9%) in subjects with a PSA < or = 4 ng/mL, and the percentage of negative biopsy cores with a normal TRUS was high (98%) in subjects with a PSA of < or = 4 ng/mL, but lower (67%) in subjects with a PSA > 10 ng/mL.

Conclusion: The serum PSA assay was more useful than either DRE or TRUS in detecting prostate cancer. The percentage of bone metastasis increased concomitant with the number of positive biopsy cores, and the positive biopsy rate of hypoechoic areas positively correlated with the PSA level.