Experience with an assay for prostate-specific antigen and transrectal ultrasonography in the diagnosis of prostate cancer.

Abstract

To assess the detection of prostate cancer using the Ciba Corning ACS 180 prostate-specific antigen (PSA) assay and transrectal ultrasonography (TRUS) in a district general hospital. In a preliminary study, the serum PSA level in 130 patients was measured using both the Ciba Corning and the Hybritech Tandem-R PSA assay and the results assessed using linear regression analysis. A further study 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 Corning assay), digital rectal examination (DRE) and TRUS findings. The PSA levels measured using the Ciba Corning assay were about 50% higher than those using the Hybritech Tandem-R assay. Of 204 men who had TRUS and biopsy. 56 (28%) had detectable prostate cancer, but no patient with a PSA of < 6.0 ng/mL had. Five of 47 (11%), 21 of 83 (25%) and 30 of 65 (46%) patients with PSA levels in the range 6.1-15.15.1-30 and > 30 ng/mL, respectively, had cancer 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 was positive (P < 0.001). In men with a PSA level of 6.1-15.0 ng/mL, positive biopsies were found in 3% when the DRE was negative, compared with 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. Of these 54, there were 43 with hypoechoic lesions, of whom 22 (51%) had positive biopsies. The cancer detection rate was higher when both TRUS 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 positive, 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 < 0.005). However, when the DRE was negative there was no significant difference in the cancer detection rates for TRUS-positive and TRUS-negative patients, where four of 20 and 14 of 91 (15%) patients were found to have cancer, respectively. The positive biopsy rates in this study were comparable with those from similar studies using other PSA assays. When the DRE was negative there was a low detection rate for 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 rate for TRUS-negative patients did not differ from TRUS-positive patients, indicating the importance of random systematic biopsies.