[The digital rectal exam, prostate-specific antigen and transrectal echography in the diagnosis of prostatic cancer]

This study analyzes the three available clinical methods in the diagnosis of prostate cancer (PC): digital rectal examination (DRE), serum prostate specific antigen (PSA) and transrectal ultrasound (TRUS), and attempts to establish the best system in the early detection of PC.

The findings of DRE, serum PSA and TRUS of the prostate in patients in which a TRUS-guided prostate biopsy was performed initially, and prostate surgery afterwards (TURP in 72%, radical retropubic prostatectomy in 20% and simple prostatectomy in 8%), are retrospectively analyzed.

PC was eventually found in 50 patients (56%). Seventy-eight patients had an abnormal DRE, 44 of which had a final diagnosis of PC (sensitivity = 94%, specificity = 20.5%). Serum PSA levels were available in 60 cases before diagnosis. Levels > 4 ng/ml were found in 32 of 38 cases with PC (sensitivity = 84%, specificity = 31%). The TRUS finding with the highest positive predictive value (PPV) for PC was diffuse prostate heterogeneity (77.8%). When a hypoechoic nodule was seen in the prostate peripheral zone, PC was found in 53.7%. Different combinations of the three methods are analyzed, trying to increase the diagnostic capabilities of each isolated test. Transrectal ultrasound-guided prostate biopsy detected 44 (88%) of the 50 cases with PC, its negative predictive value being 86.7%. Prostate tissue valid for histologic diagnosis was obtained in 97% of the cases, and the predictive value of the true tumor grade was 84.1%. The general complication rate attained 3.4%, none being of the septic type.

When parallel testing was examined (one or more tests being abnormal), the most efficient combination in the early detection of PC was when DRE was suspicious or serum PSA > 4 ng/ml (sensitivity = 95%, PPV = 62%). When at least two diagnostic tests were abnormal (serial testing), the most efficient combination to confirm the presence of this tumor was an abnormal TRUS and a serum PSA > 10 ng/ml (specificity = 86%, PPV = 88%).