Free and total prostate-specific antigen serum concentrations do not help to detect prostate cancer in patients with urinary outlet obstruction

Abstract

Objectives: To determine whether different molecular forms of prostate-specific antigen (PSA) obtained before transurethral resection of the prostate (TURP) indicate the presence of prostate cancer.

Patients and methods: The free, total and free-to-total PSA levels were measured in 261 patients scheduled for TURP, 20 of whom had known prostate cancer. The tissue histology was compared with the PSA levels and the patients were followed for 5 years.

Results: Prostate cancer was detected in 23 of the patients (9%) who were thought to have benign disease. Normal ranges for the distribution of the PSA levels were established based on the patients with a benign histology, but these ranges did not detect most of the unknown cancers. The sensitivity of the total PSA test in detecting cancer was 38% and the specificity 90%. The discrimination was no better when considering the free fraction or the free-to-total PSA level. However, none of the 14 patients whose cancer was missed showed general progression of the disease during the 5-year follow-up and only one died from prostate cancer. In contrast, eight of the 20 patients with a known prostatic malignancy showed general progression, and six died from the disease.

Conclusion: PSA testing of patients with outlet obstruction often failed to detect prostate cancer, but the prognosis was moderately good in those patients in whom it was missed.