Effectiveness of antibiotic treatment given to patients for an abnormal prostate specific antigen before prostate biopsy

Abstract

Objective To analyze the effect of antibiotic treatment on prostate specific antigen (PSA) derivations in patients with and without prostate cancer and to further determine if the changes of PSA values after antibiotic treatment could help to exclude inflammation in the differential diagnosis of an abnormal PSA. Methods A total of 100 patients with lower urinary tract symptoms,a PSA level of 4 to 10 μg/L,free PSA/total PSA (fPSA/tPSA) ratio ＜ 0.25,and a negative digital rectal examination and transrectal ultrasonography were enrolled in this study.All patients received 500 mg of ciprofloxacin twice a day for 3 weeks.Free and total PSA values were measured before and after antibiotic treatment.All the patients were then scheduled for 12-core prostate biopsy. Results The mean tPSA value was (6.5 ± 1.2) and (5.1 ± 1.2) μg/L respectively before and after antibiotic treatment ( P ＜ 0.01 ).Ninety-one patients (91.0％) showed tPSA reduction after antibiotic therapy,of which 13 ( 14.3％ ) had prostate cancer on biopsy.In 17 cases (18.7％) post-treatment tPSA was less than 4 μg/L.Three of the 17 cases (17.6％)had prostate cancer on biopsy.In 6 of the 100 men post-treatment tPSA was between 4 and 10 μg/L and the fPSA/tPSA ratio was above 0.25.One of these cases had prostate cancer on biopsy.Seven cases had a ＞50％ reduction in PSA levels with no positive biopsy results.Although mean total PSA and PSAD decreased after treatment in both groups,the reductions within these parameters were not significantly different between patients with and without prostate cancer (P ＞ 0.05).Furthermore,no differences emerged in terms of the changes of other PSA derivations including fPSA and fPSA/tPSA ( P ＞ 0.05 ). Conclusions The PSA levels may change with long-term antibiotic treatment in patients with elevated PSA values.A decrease in PSA after antibiotic treatment does not rule out the presence of prostate cancer even if PSA decreases to a normal level.But a ＞ 50％ reduction in PSA levels may be associated with a decreasing risk of prostate cancer,which may allow a postponement of prostate biopsy in selected patients. Key words: Prostatic neoplasms; Carcinoma; Prostate specific antigen; Prostate biopsy; Antibiotic treatment