EXPERIENCE WITH AN ASSAY FOR PROSTATE-SPECIFIC ANTIGEN AND TRANSRECTAL ULTRASONOGRAPHY IN THE DIAGNOSIS OF PROSTATE-CANCER

Objective To assess the detection of prostate cancer using the Ciba Co ming ACS 180 prostate-specific antigen (PSA) assay and transrectal ult rasonography (TRUS) in a district general hospital. Patients and metho ds In a preliminary study, the serum PSA level in 130 patients was mea sured using both the Ciba Coming and the Hybritech Tandem-R PSA assay and the results assessed using linear regression analysis. A further s tudy comprised 204 consecutive patients who underwent TRUS and biopsy. The histology of the prostatic biopsies was analysed according to the pre-biopsy PSA level (Ciba Coming assay), digital rectal examination (DRE) and TRUS findings. Results The PSA levels measured using the Cib a Coming assay were about 50% higher than those using the Hybritech Ta ndem-R assay. Of 204 men who had TRUS and biopsy, 56 (28%) had detecta ble prostate cancer, but no patient with a PSA of < 6.0 ng/mL had. Fiv e of 47 (11%), 21 of 83 (25%) and 30 of 65 (46%) patients with PSA lev els in the range 6.1-15, 15.1-30 and >30 ng/mL, respectively, had canc er detected. When the DRE was negative, 18 of 111 (16%) patients had a positive biopsy, compared with 38 of 93 (41%) patients when the DRE w as positive (P<0.001). In men with a PSA level of 6.1-15.0 ng/mL, posi tive biopsies were found in 3% when the DRE was negative, compared wit h 27% when it was positive (P<0.025). A TRUS abnormality was detected in 54 of 204 (26%) patients, of whom 25 (46%) had positive biopsies. O f these 54, there were 43 with hypoechoic lesions, of whom 22 (51%) ha d positive biopsies. The cancer detection rate was higher when both TR US and DRE were positive (62%), with the highest detection rate (86%) occurring when the PSA level was also >30.0 ng/mL. When the DRE was po sitive, cancer was detected in 21 of 34 (62%) patients with a positive TRUS, but only in 17 of 59 (29%) patients with a negative TRUS (P<0.0 05). However, when the DRE was negative there was no significant diffe rence in the cancer detection rates for TRUS-positive and TRUS-negativ e patients, where four of 20 and 14 of 91 (15%) patients were found to have cancer, respectively. Conclusions The positive biopsy rates in t his study were comparable with those from similar studies using other PSA assays, When the DRE was negative there was a low detection rate f or cancer of 3% for men with PSA levels of 6.1-15.0 ng/mL. In patients with an elevated PSA level but a negative DRE, the positive biopsy ra te for TRUS-negative patients did not differ from TRUS-positive patien ts, indicating the importance of random systematic biopsies.