Diagnostic value of percent free prostate-specific antigen: retrospective analysis of a population-based screening study with emphasis on men with PSA levels less than 3.0 ng/mL

OBJECTIVES: To retrospectively investigate the use of percent free prostate-specific antigen (PSA) compared with total PSA in serum as predictor of prostate cancer in men selected randomly from the general population who underwent biopsy on the basis of abnormal findings on digital rectal examination (DRE) or transrectal ultrasound (TRUS) and/or serum PSA levels greater than 10 ng/mL. METHODS: A single intervention, population-based screening study was undertaken in 1988 and 1989. Of the 2400 men aged 55 to 70 years invited to participate, 1782 men responded and were examined with DRE, TRUS, and PSA testing (Tandem-Hybritech). In 1995, frozen serum samples from 1748 men were analyzed for percent free PSA (Prostatus, Wallac OY). Five-year follow-up data on new cancers in the screened population were obtained from the Swedish Cancer Registry (SCR). RESULTS: Of the 1748 men, 367 underwent TRUS-guided biopsies because of abnormal findings on either DRE or TRUS or serum PSA levels of greater than 10 ng/mL. This resulted in the diagnosis of 64 cases of prostate cancer (3.7%). PSA levels of 3.0 ng/mL or greater were found in 55 (86%) of 64 cancer cases and in 399 (24%) of the 1684 benign cases. Among the 1294 men with PSA less than 3.0 ng/mL, 9 prostate cancers were diagnosed (14% of all prostate cancers). All 9 patients with cancer and with PSA less than 3.0 ng/mL had a percent free PSA of 18% or less. In the group of 1109 patients with PSA less than 3.0 ng/mL and a percent free PSA greater than 18%, 159 biopsies were performed because of abnormal DRE or TRUS. However, no prostate cancer was diagnosed in this category of patients. Five years after the screening intervention, 7 more cases of prostate cancer were clinically diagnosed in the screened population according to the SCR. CONCLUSIONS: The combination of PSA levels less than 3.0 ng/mL and percent free PSA greater than 18% defines a large part of the population at a very low risk of cancer of the prostate both at the time of screening and during the following 5 years. Men in this group may be spared DRE, and longer screening intervals may be considered. However, the risk of having prostate cancer is not negligible in men with PSA less than 3.0 ng/mL and percent free PSA of 18% or less. The results of this study indicate that biopsy should be recommended to men fulfilling these criteria, although these results should be confirmed in larger prospective studies because of the limited number of patients with prostate cancer in the present series

Lead time associated with screening for prostate cancer.

Screening serum levels of prostate-specific antigen (PSA) is now a major strategy for early detection of prostate cancer (PC). Quantification of the lead time thus obtained is important both for understanding the development of PC and for evaluating the advantages and disadvantages of widespread screening. In our study, 1,233 randomly selected men living in Stockholm in 1988 were invited to participate in an early detection (ED) program, in which suspicious findings provided by digital rectal examination (DRE), transrectal ultrasonography (TRUS) and/or a PSA value >/=10.0 ng/mL were followed up by biopsy. The cumulative incidence (Kaplan-Meier) of PC in the 946 participants (ED) during 12 years of follow-up was compared to that of an age-matched, randomly selected reference population (RP) of 657 men for whom PSA values (from frozen serum samples) could also be obtained. The PC incidence in men in the RP with PSA values >/=3.0 ng/mL reached the corresponding level for the ED group after 10.6 years (the "catch-up" point). After 12 years of follow-up, the estimated median lead time for men with PSA values in this interval was 4.5 years in the ED population, compared to 7.8 years in the RP. With 20 years of follow-up, the estimated median lead time of the RP was enhanced to 10.7 years. The lead time in connection with PC was influenced by the initial PSA level (although with large variations), length of follow-up and sensitivity of the ED procedure employed. The ED program described here was not associated with major overdetection

Soluble urokinase plasminogen activator receptor as a prognostic marker in men participating in prostate cancer screening.

BACKGROUND: The urokinase plasminogen activator (uPA) system is involved in tissue remodelling processes and is up-regulated in many types of malignancies. We investigated whether serum levels of different forms of soluble uPA receptor (suPAR) are associated with survival and in particular with prostate cancer and cardiovascular disease mortality. METHODS: Using time-resolved fluorescence immunoassays, we measured intact suPAR [suPAR(I-III)] and intact plus cleaved suPAR [suPAR(I-III) + suPAR(II-III)] and thus calculated the amount of suPAR(II-III) in serum samples from 375 men participating in a prostate cancer screening trial. A total of 312 men were free of prostate cancer and 63 men had prostate cancer diagnosed at the time of screening. The cohort was followed for 15 years. We assessed survival using Kaplan-Meier estimation and Cox proportional hazards regression. RESULTS: The mean age at blood sampling was 64 years. In total, 152 men died during follow-up. SuPAR(I-III) and suPAR(II-III) were significantly positively associated with mortality (P = 0.001 and P < 0.0001, respectively). In a Cox regression model adjusting for age and prostate cancer status, an increase in suPAR(I-III) and suPAR(II-III) by 1-unit (ln-scale) was associated with a hazard ratio (HR) of 2.26 [95% confidence interval (CI) 1.17-4.35] and 2.53 (95% CI 1.56-4.10), respectively. There was a trend towards an increased risk of death from prostate cancer in screening-detected prostate cancer patients with increased values of either suPAR form. However, this difference was not significant and the association disappeared after adjusting for age, tumour stage, tumour grade and prostate-specific antigen. Being in the highest quartile of any of the suPAR forms was associated with a highly significant increased risk of cardiovascular death, with HR adjusted for age of 3.27 (95% CI 1.38-7.73) for suPAR(I-III) quartile 4 versus quartile 1. Conclusions.  High concentrations of serum suPAR(I-III) and suPAR(II-III) were associated with poor overall survival. The association was particularly strong for death from cardiovascular disease. No similar association was found for prostate cancer after adjustment for other prognostic factors

Variation in percentage-free prostate-specific antigen (PSA) with prostate volume, age and total PSA level.

OBJECTIVE: To examine the correlation between prostate volume, patient age and total prostate-specific antigen (tPSA) with the percentage-free PSA (f/tPSA) in a population-based cohort of men with no prostate cancer and with a tPSA of < 10.0 ng/mL. SUBJECTS AND METHODS: Men who in 1988-1989, after randomized selection in the general population, participated in a population-based screening study for prostate cancer, were investigated. In all, 1622 of the men (aged 55-70 years) were considered free from prostate cancer and had a tPSA level of < 10.0 ng/mL. The f/tPSA and tPSA were determined in frozen sera from each individual, and related to prostate volume and age measured at the time of the study. The entire population was investigated, as were four subpopulations based on tPSA levels (< 2.0, 2.0-3.9, 4.0-6.9 and 7.0-9.9 ng/mL). Statistical calculations included multiple regression and correlation analysis. RESULTS: The f/tPSA level varied with prostate volume and age, but the decisive factor for this variation was the tPSA level. The closest correlation was in the tPSA interval 7.0-9.9 ng/mL, where volume and age together explained 47% of the variation in f/tPSA. Also, for men with tPSA levels in each of the intervals 2.0-3.9, 4.0-6.9 and 7.0-9.9 ng/mL, the f/tPSA increased with higher prostate volumes and age. In men with tPSA levels of < 2.0 ng/mL the f/tPSA was not affected by variations in prostate volume or age. CONCLUSION: The variation in f/tPSA with prostate volume, age and tPSA is highly dependent on the tPSA level. Volume and age in the tPSA interval 7.0-9.9 ng/mL can explain almost half the variation in f/tPSA, whereas this influence is insignificant in men with a tPSA of < 2.0 ng/mL