Can Antibiotic Therapy avoid Unnecessary Biopsy in Males with Marginally Elevated PSA Levels?
Abstract
Introduction: Prostate specific antigen (PSA) is widely used for screening and early detection of prostate cancer. However, PSA is not a cancer specific tumor marker and the levels would be influenced by coexistent diseases particularly prostatic infections, which are common in third world countries. We evaluated the effects of antibiotic treatment on serum total prostate specific antigen, free prostate specific antigen and percent free prostate specific antigen in men with prostate specific antigen between 4 and 10 ng/ml with no hard areas on digital rectal examination (DRE).
Materials and Methods: 142 men with PSA levels between 4 and 10 ng/dl, were enrolled in this prospective study. Exclusion criteria were patients with urinary tract infection as evidenced by pyuria and documented history of prostatitis. Basal total-PSA (t-PSA) and free-PSA (f-PSA) were determined using immunometric assay technique based on chemiluminescence method. Ofloxacin (200mg twice a day was given orally for 1 week followed by 100mg at bedtime for three weeks) was given in these patients. t-PSA and f-PSA levels were repeated 4 weeks after therapy. Patients with persistently raised PSA (>4 ng/ml) after a course of antibiotic therapy underwent prostate biopsy whereas patients with PSA reductions were followed up with regular PSA assays to note for any increase in values.
Results: The mean age of the patients was 67 ± 6.7 years. The patients were randomly divided into 2 groups. Group A consisted for men who were given antibiotic therapy for a period of 4 weeks. Men followed up with repeat PSA levels without antibiotics were categorized as Group B. Mean t-PSA was 6.09 ± 1.34 and 3.84 ± 1.25 ng/ml before and after treatment, respectively (mean change -2.25 ± 0.52, p < 0.001) in Group A. 47 out of 102 (46.07%) in Group A had a reduction in PSA levels < 4 ng/ml after antibiotic therapy. Group B included 40 patients, out of which 10 patients (25 %) had reduction in PSA levels during one month of follow up. Out of the 55 patients in Group A, where the PSA levels did not decline with antibiotic therapy, who underwent prostate biopsy, 30 (54.54%) patients did not harbor malignancy. 19 out of these patients had chronic prostatitis on histological examination. There was an increase in %f-PSA by 7.19% in patients on antibiotic therapy and 9.49% in patients without antibiotics.
Conclusions: Antibiotic therapy significantly reduced PSA levels in males with borderline elevated PSA. Empirical antibiotic treatment in asymptomatic patients with a PSA level 4-10 ng/ml and a normal DRE could be used to select candidates for prostate biopsy, especially in third world countries where incidence of subclinical prostatitis is more prevalent. % f-PSA seemed to be a better tool to evaluate patients after a course of antibiotics.
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