Relationship between prostatic epithelial volume and serum prostate-specific antigen levels.

OBJECTIVES

The present study was designed to determine the relationship between serum prostate-specific antigen (PSA) levels and prostatic epithelial volumes.

METHODS

Forty-two men between the ages of 50 and 79 years of age with either an abnormal digital rectal examination (DRE) or a serum PSA level > 4 ng/dL underwent transrectal ultrasonography (TRUS) and ultrasound-guided random systematic biopsy of the prostate. The volumes of the peripheral zone (PZ) and transition zone (TZ) were calculated, assuming that the total prostate and TZ are ellipsoidal structures. Six random systematic biopsies were directed into the PZ and four random systematic biopsies were directed into the TZ under ultrasound guidance. Among the 42 patients undergoing prostatic biopsy, adenocarcinoma of the prostate was identified in 21 (50%). Tissue sections obtained from the biopsy specimens of the subjects without histologic evidence of prostate cancer were stained with Mallory trichrome stain, and the percentage area density of epithelium in the biopsy cores was determined using computer-assisted color image analysis. The relationships between serum PSA and total, PZ, and TZ epithelial volumes, and serum PSA and total, PZ, and TZ prostatic volumes were determined using regression analysis.

RESULTS

The difference between the mean percentage epithelial density of the PZ (17.79 +/- 1.40%) and TZ (10.32 +/- 0.82%) was statistically significant (p < 0.0001). The mean volumes of epithelium in the PZ and TZ were 4.25 +/- 0.47 cc and 3.39 +/- 0.45 cc, respectively. The p and r2 values for the relationship between serum PSA and total prostatic volume were 0.016 and 0.260, respectively. Statistically significant correlations were also observed between serum PSA levels and TZ epithelial volumes (p = 0.0009; r2 = 0.449) and serum PSA levels and TZ volumes (p = 0.007; r2 = 0.329). Statistically significant correlations were not observed between serum PSA levels and the following parameters: PZ volume, PZ epithelial volume, and total prostatic epithelial volume.

CONCLUSIONS

Although the PZ contains a significantly greater area density and absolute volume of epithelium than the TZ, the serum PSA level is most strongly correlated only with the volume of epithelium in the TZ.