Antimicrobial therapy for asymptomatic patients with elevated prostate-specific antigen: can the change in prostate-specific antigen reliably guide prostate biopsy decisions?

OBJECTIVES: To assess the effects of a 4-week levofloxacin course on PSA in asymptomatic men with elevated prostate-specific antigen (PSA) and on prostate biopsy decision.
METHODS: Fifty asymptomatic men with elevated PSA (4.0-10.0 ng/dl) were given levofloxacin 500 mg/day for 4 weeks followed by repeat PSA. Prostate biopsy was recommended at the end of the study. We compared pre- and post-treatment PSA as well as PSA changes between prostate cancer cases and non-cancer patients.
RESULTS: Mean (±SD) PSA decreased from 6.91 ± 2.13 to 6.05 ± 3.0 ng/dl after antimicrobial treatment (p = 0.025). Twenty-five (56.8%) patients had a post-treatment decrease in PSA, including 20 (45.5%) patients to <4.0 ng/dl and/or >25% of the initial PSA value. The difference in PSA change between prostate cancer and non-cancer patients was not statistically significant (p = 0.104).
CONCLUSIONS: Levofloxacin resulted in an overall decrease in PSA for asymptomatic men with PSA in the 4-10 ng/dl range. PSA changes, however, were not significantly different between patients with prostate cancer and non-cancer patients. Prostate cancer was detected in 20% of patients with a clinically relevant PSA decline.