We identified from our clinical database a total of 471 patients affected by cat. II chronic bacterial prostatitis (CBP), cat. III (IIIa and IIIb) chronic pelvic pain syndrome (CP/CPPS), or cat. IV asymptomatic inflammatory prostatitis (AIP), according to NIH criteria. 132 intent-to-treat patients, showing levels of PSA > or =4 ng/mL, were subjected to a 6-week course of combination pharmacological therapy with 500 mg/day ciprofloxacin, 500 mg/day azithromycin (3 days/week), 10 mg/day alfuzosin and 320 mg b.i.d. Serenoa repens extract. At the end of treatment, 111 per-protocol patients belonging to all categories of prostatitis showed a total 32.5% reduction of PSA levels. In the same group, 66 patients (59.4%) showed "normalization" of PSA values under the 4 ng/mL limit. Patients affected by cat. IIIb CP/CPPS showed the highest PSA reduction and normalization rates (40% and 68.4%, respectively). Follow-up data show that, after a marked, significant reduction at completion of therapy, PSA levels, urine peak flow rates and NIH-CPSI symptom scores remained constant or decreased throughout a period of 18 months in patients showing normalization of PSA values. Prostatic biopsy was proposed to 45 patients showing persistently high PSA values (> or = 4 ng/mL) at the end of treatment. Fourteen patients rejected biopsy; of the remaining 31, 10 were diagnosed with prostate cancer. Four months after a first biopsy, a second biopsy was proposed to the 21 patients with a negative first diagnosis and persistently elevated PSA levels. Three patients rejected the procedure; of the remaining 18, four were diagnosed with prostatic carcinoma. In summary, combination pharmacological therapy decreased the number of patients undergoing prostatic biopsy from 111 to 45. Normalization of PSA values in 59.4% of patients--not subjected to biopsy--increased the prostate cancer detection rate from 12.6% (14/111) to 31.1% (14/45). The reduction of PSA after a 6-week course of therapy was calculated in patients affected by cat. II, IIIa, IIIb and IV prostatitis after stratification with respect to the concomitant presence or absence of benign prostatic hyperplasia (BPH). PSA was reduced by 41% in cat. II CBP patients without BPH, compared to a 12.7% reduction in patients affected by BPH. Cat. IIIa CP/CPPS patients without BPH showed a 58.3% reduction of PSA levels, compared to a 20.7% reduction observed in CPPS/BPH patients. These data show that the presence of BPH may prevent the reduction of PSA induced by combination pharmacological therapy, and suggest that care has to be taken in the adoption of PSA as a marker of therapeutic efficacy in the presence of confounding factors like BPH. PSA should in our opinion be used as a significant component of a strategy integrating multiple diagnostic approaches.