Objectives: To determine if the serum testosterone (T) concentration influences the ability of prostate-specific antigen (PSA) to predict prostate cancer volume and stage.
Methods: One hundred consecutive patients with clinically localized prostate cancer who underwent radical prostatectomy were examined prospectively. Each patient was evaluated preoperatively with a serum PSA, total T, free T, and percent free T. All surgical specimens were evaluated using the whole mount, step section technique for Gleason score, tumor volume, and extraprostatic disease.
Results: Serum total T, free T, and percent free T did not correlate with the serum PSA level (r = .03, .08, and .07, respectively), tumor volume (r = .11, .08, and .11, respectively), prostate weight (r = .00, -.08, and .11, respectively), or Gleason score (r = .11, .08, and .11, respectively). Serum PSA correlated with tumor volume (r = .51, P < 0.0001). Extraprostatic disease was significantly associated with a higher percent free T value (r = .26, P = 0.02) but not with either the total or the free T level. Linear regression analysis showed that neither the total nor the free T concentration was a significant predictor of extraprostatic disease in the presence of PSA (P = 0.30 and 0.24, respectively); percent free T contributed only slightly to PSA in the prediction of extraprostatic disease (P = 0.05). However, neither total T, free T, nor percent free T was a significant predictor of tumor volume; in essence, the association between PSA and tumor volume was independent of the serum T concentration (P = 0.30, 0.24, and 0.60, respectively).
Conclusions: Serum total T, free T, and percent free T values do not enhance the ability of PSA to predict the tumor volume or pathologic stage in patients with clinically localized prostate cancer.