Prostate specific antigen decrease and prostate cancer diagnosis: antibiotic versus placebo prospective randomized...

Prostate inflammation can lead to an increase in serum prostate specific antigen concentration and confound the use of prostate specific antigen kinetics. Repeat prostate specific antigen measurements after a period of observation or a course of empirical antibiotics are controversial in terms of the optimal approach to reduce the confounding impact on prostate cancer screening. This issue was analyzed in patients with a diagnosis of type IV or asymptomatic prostatitis (National Institutes of Health classification) and high prostate specific antigen.

We studied 200 men between 50 and 75 years old with a high prostate specific antigen (between 2.5 and 10 ng/dl). Of these patients 98 (49%) had a diagnosis of type IV prostatitis. In a prospective, double-blind trial they were randomized to receive placebo (49 patients, group 1) or 500 mg ciprofloxacin (49 patients, group 2) twice a day for 4 weeks. Prostate specific antigen was determined after treatment and all patients underwent transrectal ultrasound guided biopsy of the prostate.

In group 1, 29 (59.18%) patients presented with a decrease in prostate specific antigen and 9 (31%) had cancer on biopsy, while in group 2 there were 26 (53.06%) patients with a decrease in prostate specific antigen and 7 (26.9%) with prostate cancer. There was no statistical difference in either group in relation to prostate specific antigen decrease after treatment or the presence of tumor.

A considerable number of patients (49%) were diagnosed with type IV prostatitis and high prostate specific antigen in agreement with the current literature. Of the patients 26.9% to 31% presented with a decrease in prostate specific antigen after the use of antibiotic or placebo and harbor cancer as demonstrated on prostate biopsy. Prostate specific antigen decreases do not indicate the absence of prostate cancer.