Free to total prostate-specific antigen (PSA) ratio improves the discrimination between prostate cancer and benign prostatic hyperplasia (BPH) in the diagnostic gray zone of 1.8 to 10 ng/mL total PSA.

OBJECTIVES

Improved discrimination between prostate cancer (PC) and benign prostatic hyperplasia (BPH) is clearly needed. Our aim in this study was to evaluate whether the free to total prostate-specific antigen (PSA) ratio would be useful in the gray zone of 1.8-10 ng/mL total PSA range.

METHODS

In a consecutive series of 435 clinic patients referred for prostate evaluation, 308 had a total PSA < 10 ng/mL (92 had PC and 216 BPH). Free and total PSA were measured, and the free to total PSA ratio calculated.

RESULTS

Total PSA values were significantly different between the two groups. For the 200 patients with a total PSA < 6 ng/mL, no significant difference in total PSA values were seen (P = 0.411), whereas free to total PSA ratios remained statistically different (P < 0.001). Receiver operating characteristic (ROC) curve analysis comparing the performances of total PSA over the ratio of free to total PSA showed a clear advantage for the ratio at all sensitivity levels.

CONCLUSIONS

These data demonstrate that in a significant number (n = 308) of prostatic patients in the diagnostic gray zone of 1.8-10 ng/mL total PSA, the routine use of free to total PSA might be advantageous in discriminating between cancer and benign hyperplasia. This advantage remained for total PSA < 4 ng/mL. Further study is warranted to confirm these findings in an unselected population.