[Analysis of biologic changes in PSA blood concentration and free PSA percentage in patients with normal rectal digital examination]

Effect of Antibiotic Treatment on Serum PSA and Percent Free PSA Levels in Patients with Biochemical Criteria for Prostate Biopsy and Previous Lower Urinary Tract Infections

Background

Controversy exists as to the influence of inflammatory foci on total and free prostate-specific antigen (PSA) concentrations. The objective was to analyze the biological variations of PSA and percent free PSA (%f-PSA) in patients with biochemical criteria for prostate biopsy (PSA higher than 4 ng/mL and normal rectal examination) and compare them with the variation induced by antibiotic treatment in a cohort of patients with a history of lower urinary tract infections and no clinical evidence of prostatitis.

Methods

Ninety patients with a history of lower urinary tract infections, non-suspicious digital rectal examination and PSA between 4 and 20 ng/mL were analyzed. PSA concentration and %f-PSA were determined. Forty-five patients were treated with three weeks of ofloxacin, following which marker determination was repeated. All patients underwent ultrasound-controlled transrectal six-core prostate biopsy.

Results

Sixty-seven patients presented benign prostatic hyperplasia (BPH) (30 with prostatitic foci) and 23 cancer. Significant variations in PSA (6.97 ng/mL vs. 5.82 ng/mL, p=0.001) and %f-PSA (14.84% vs. 17.53%, p=0.01) were found only in the treated patients. These differences were significant for patients with BPH-associated prostatitic foci and not for patients with BPH or cancer. The tendency was for PSA to decrease (15 treated patients with PSA <4 ng/mL vs. six non-treated patients) and for %f-PSA to increase. The median variation of %f-PSA was greater than that of PSA. When the cutoff for %f-PSA was set at 25%, 18.9% of unnecessary biopsies after the first determination and 20% after the second could be avoided. By associating the reduction in PSA, up to 46% could be avoided in treated patients.

Conclusion

Biochemical criteria for prostate biopsy may be modified in patients with a history of lower urinary tract infections due to variations greater than those explained by intraindividual biological variations, and may be influenced by the antibiotic treatment. These results suggest that subclinical inflammatory foci may influence PSA and %f-PSA.

Cost-effectiveness of percent free PSA for prostate cancer detection in men with a total PSA of 4-10 ng/ml

OBJECTIVE

To assess the cost-effectiveness of two diagnostic strategies for prostate cancer in men with prostate-specific antigen (PSA) levels of 4-10 ng/ml and normal digital rectal examination (DRE).

DESIGN

Cost-effectiveness analysis was performed using a decision tree model. Data collection and a systematic review of patients at the Urology Department (Carlos Haya Hospital) were made. 101 patients over the age of 40 with PSA levels of 4-10 ng/ml and normal DRE were selected. Transrectal ultrasound-guided prostate biopsy (TRUS-Bx) and percent free PSA testing prior to TRUS-Bx were performed. The outcome measures used were the incremental cost-effectiveness ratio, and costs were calculated through activity-based costing. The effectiveness was measured by means of the number of detected cases, test utility and actual cases (detected cases minus lost cases).

RESULTS

Using base-case analysis, the strategy of percent free PSA + TRUS-Bx was found to be the most cost-effective. The incremental cost-effectiveness ratio for free PSA + TRUS-Bx compared with TRUS-Bx was EUR 2,277.40. Strategy 2 (TRUS-Bx) would be more cost-effective if the cost of percent free PSA increased to EUR 21.64 or if prostate cancer prevalence increased to 26%.

CONCLUSIONS

The use of percent free PSA prior to TRUS-Bx is the most cost-effective diagnostic strategy. However, this result is very sensitive and strategy 2 (TRUS-Bx) would be more cost-effective if the cost of the percent free PSA increased to EUR 21.64 or if the prevalence of prostate cancer increased to above 26%.

[Effect of antibiotic treatment on PSA and percentage of free PSA in patients with biochemical criteria of prostatic biopsy]

INTRODUCTION

PSA serum level measurement in the most important tool in the early diagnosis of prostate cancer patients. However, it is recognised it low specificity is due mainly to prostatic benign diseases. Although it is known that inflammation can contribute on this lack of specificity, there is disagreement in the effect of no symptomatic prostatic inflammatory focus on total PSA and percent free PSA serum levels.

AIM

To analyse the biological variability in total PSA and percent free PSA serum levels in patients with biochemical criteria of prostatic biopsy and to compare them with the antibiotic induced variability in a previous urinary infections cohort patients.

PATIENTS AND METHODS

We analysed 60 patients with previous urinary infections, normal digital rectal examination and PSA between 4 and 20 ng/ml. We measured total PSA and percent free PSA serum levels. Thirty were treated with 3 weeks of ofloxacin and following a new marker determination. Sextant ultrasound guided prostatic biopsy was performed in all cases.

RESULTS

45 patients demonstrated BPH (29 with prostatitis) and 15 prostate cancer (T1c). Significant variations were found on total PSA serum levels (6.97 ng/ml vs 5.82 ng/ml, p = 0.001) and percent free PSA (14.73% vs 17.77%, p = 0.01) only in treated patients. These differences were significant in BPH and BPH with prostatitis patients but not in prostate cancer patients. Treated patients trend was to decrease PSA (13 treated patients shown PSA < 4 ng/ml vs 2 control patients) and to increase percent free PSA. The median variation of percent free PSA was higher than total PSA and was not influenced by PSA level or prostatic volume. Taking 25 as cut-off of percent free PSA, 18.3% of prostatic biopsies could be avoided in the first determination and 20% in the second. Adding the total PSA reduction, 56% of prostates biopsies in the treated patients could be avoided.

CONCLUSIONS

Biochemical criteria of prostatic biopsy could be modified in patients with previous urinary infections due to higher variations on serum markers than those explained by biological variations. These variations could be induced by the antibiotic treatment. These results suggested that the inflammatory focus could influence on total PSA and percent free PSA serum levels.