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

Abstract

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.