PREDICTIVE VALUE OF TOTAL AND PERCENT FREE PROSTATE SPECIFIC ANTIGEN IN HIGH GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA LESIONS: RESULTS OF THE TYROL PROSTATE SPECIFIC ANTIGEN SCREENING PROJECT

Abstract

We evaluate the predictive values of total and percent free prostate specific antigen (PSA) in regard to high grade intraepithelial lesions in volunteers who participated in the Tyrol PSA Screening Project. Between June 1995 and December 1998, 1,474 patients undergoing transrectal biopsy of the prostate were evaluated. The primary detection rates of prostate cancer and high grade intraepithelial lesions were evaluated. In addition, the rate of prostate cancer detected on biopsy in patients diagnosed with high grade prostatic intraepithelial neoplasia on the previous biopsy was assessed. Mean total PSA values and mean percent free PSA levels were determined for each study group and compared using the Mann-Whitney U test. A total of 1,077 (73.1%) volunteers had benign prostatic hyperplasia or prostatitis, and 327 (22.2%) had prostate cancer. The primary detection rate for high grade intraepithelial lesions was 4.7% (70 patients) and on repeat biopsy was 38.6% (27). Mean total PSA for the benign prostatic hyperplasia, prostate cancer, high grade and intraepithelial cancer groups were 6.0, 8.7, 5.9 and 5.2 ng./ml., respectively. Mean percent free PSA values for the various groups were 21.9, 12.1, 15.0 and 12.0, respectively. In regard to total PSA there was a statistically significant difference between the prostate cancer and high grade prostatic intraepithelial neoplasia groups (p = 0.016), as well as the prostate cancer and intraepithelial cancer groups (p = 0.028). However, the high grade and intraepithelial cancer groups did not differ significantly. In regard to percent free PSA there were statistically significant differences between the prostate cancer and high grade prostatic intraepithelial neoplasia groups (p = 0.0001), and the high grade and intraepithelial cancer groups (p = 0.013). In regard to percent free PSA our data indicate a significant difference between high grade intraepithelial lesion and intraepithelial cancer. Due to a substantial overlap in percent free prostate specific antigen between the 2 groups, a clinically useful cutoff point could not be established. Therefore, we recommend repeat biopsy in all patients with high grade intraepithelial lesions regardless of the percent free PSA.