Influence of noncancerous prostatic tissue volume on prostate-specific antigen

Abstract

Objectives. To ascertain the influence of volume of noncancerous prostatic tissue and zone of cancer of origin on the serum prostate-specific antigen (PSA) level to predict tumor volume and pathologic stage in men with clinically organ-confined disease. Methods. We evaluated the relationship between the preoperative serum PSA level and the pathologic findings of stage, grade, and tumor volume for 128 patients who underwent radical prostatectomy. The volume of noncancerous prostatic tissue and zone of cancer origin were determined in 100 and 115 of the 128 patients, respectively. These data were then analyzed to determine their influence on the preoperative serum PSA level. Results. Serum PSA values increased as clinical and pathologic stage progressed. Despite this overall trend, we observed considerable overlap in PSA values between patients with pathologically organ-confined tumors and those with extraprostatic tumor extension and low predictive value indexes. In patients with large noncancerous prostatic tissue volume (greater than 30 cm 3) or tumor volume of 3 cm 3 or less, noncancerous prostatic tissue volume contributed significantly to the elevation of the serum PSA value and interfered with the direct relationship between PSA value and tumor volume. Although there were no significant differences in the distribution of PSA values or tumor volumes between cases with dominant peripheral and transition zone tumors, peripheral zone tumors were more likely to extend beyond the prostate. Conclusions. The volume of noncancerous prostatic tissue affects the serum PSA value and the zone of cancer origin influences pathologic stage. Thus, the serum PSA level is not useful for predicting either tumor volume or pathologic stage on an individual basis.