To examine whether subclinical prostatic inflammation might influence serum prostate-specific antigen (PSA) levels in men with clinically undetectable prostate cancer.

A total of 461 patients who underwent prostate biopsy at our hospital were studied between January 1996 and December 1999. Of these patients, a total of 125 patients without detectable prostate cancer or a history or symptoms of prostatitis, with serum PSA levels of less than 20.0 ng/mL and other specified exclusion criteria, were included in the study. Inflammation observed at biopsy was scored for inflammation extent and inflammatory aggressiveness, and the effects of these morphologic aspects of inflammation on serum PSA levels were examined.

The extent of inflammation tended to increase as the prostate volume increased (P = 0.006). Patients with a PSA greater than 2.5 ng/mL had a greater extent and aggressiveness of inflammation than those with PSA levels of 2.5 ng/mL or less (P = 0.004 and P = 0.050, respectively). However, no statistically significant differences were found in terms of the extent of inflammation or inflammatory aggressiveness between patients with PSA levels greater than 4.0 ng/mL and those with PSA levels of 4.0 ng/mL or less. Furthermore, the extent of inflammation did not account for PSA levels greater than 2.5 or 4.0 ng/mL by multivariate analysis.

Our results indicate that subclinical prostatic inflammation is not the etiology of a serum PSA greater than 4.0 ng/mL in men without clinically detectable prostate cancer.