Effectiveness of antibiotics given to asymptomatic men for an increased prostate specific antigen

Although there is controversy surrounding this subject, some urologists in daily practice often prescribe antibiotics before biopsy to men with a newly increased prostate specific antigen. We evaluated the effects of antibiotics on serum total prostate specific antigen, free prostate specific antigen, percent free prostate specific antigen and prostate specific antigen density in men with prostate specific antigen between 4 and 10 ng/ml and normal digital rectal examination. We also investigated the incidence of prostate cancer after antibiotic treatment by performing prostate biopsies in all patients regardless of posttreatment prostate specific antigen.

Between May 2006 and April 2008 a total of 100 men with total prostate specific antigen between 4 and 10 ng/ml were enrolled in this study. In addition to total prostate specific antigen, free prostate specific antigen, percent free prostate specific antigen and prostate specific antigen density values were evaluated for all of the patients. Patients with pathological digital rectal examination and urinalysis were excluded from the study. All patients received 400 mg ofloxcacin daily for 20 days. After treatment the patients were reevaluated. Regardless of the total prostate specific antigen value after therapy transrectal ultrasound guided prostate biopsy was performed.

Overall 23 men (23%) had histologically proven prostate cancer on biopsy. Mean total prostate specific antigen, free prostate specific antigen and prostate specific antigen density decreased after treatment in patients with and without prostate cancer. However, these reductions within these parameters were not significantly different between patients with and without prostate cancer. Only percent free prostate specific antigen change after treatment was found to be significantly different between patients with and without prostate cancer (p = 0.015). In 17 of the 100 men total prostate specific antigen after treatment was less than 4 ng/ml and of these 5 (29.4%) had prostate cancer on biopsy.

Although antibiotic therapy will decrease serum total prostate specific antigen, it will not decrease the risk of prostate cancer even if the prostate specific antigen decreases to less than 4 ng/ml. Therefore, prescribing antibiotics for asymptomatic men with a newly increased prostate specific antigen may not be an appropriate method of management.