Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate

Background and Objectives: The purpose of this study was to evaluate free-t o-total prostate-specific antigen (PSA) ratios after definitive external be am radiation therapy for men with adenocarcinoma of the prostate (CaP). Methods: A prospective evaluation of percent free PSA in men following defi nitive external beam radiation therapy for CaP was compared to men with unt reated CaP and men at very low risk for CaP. Statistical comparison of clin ical and pathologic parameters was performed. Results: There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA wh o were treated with external beam radiation therapy. Conclusions: Free-to-total PSA ratios after definitive external beam radiat ion therapy for CaP are consistent with percent free PSA in patients with n ewly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells. Published 1999 Wiley-Liss, Inc.dagger.