LAUSR

PURPOSE The role of percent-free PSA (%fPSA) in patients who have undergone radical prostatectomy (RP) and subsequently relapsed is unclear. We previously conducted two retrospective studies and found %fPSA ≥15 in the setting of biochemical recurrence (BCR) confers more aggressive disease. To validate that, we propose to use biobank specimens collected prospectively when patients were first diagnosed with BCR. MATERIALS AND METHOD Biobank specimens of patients with undetectable PSA after RP and then develop BCR(PSA ≥0.1) were analyzed for %fPSA. Patients were stratified according to the %fPSA cut-off of 15%. Univariable and multivariable logistic regression analysis was performed to predict covariates associated with a higher %fPSA. Cox proportional hazard models were performed to evaluate the prognostic effect of %fPSA on androgen deprivation therapy (ADT) free survival, metastasis-free survival, castrate resistant (CRPC) free survival, cancer-specific (CSS) survival. RESULTS 154 men were included in the study, of which 126 (82%) had %fPSA<15 and 28 (18%) had %fPSA≥15. Median follow up for %fPSA<15 and %fPSA≥15 was 75 and 69 months, respectively. Patients with %fPSA≥15 had increased hazard of receiving ADT (25% vs. 43%, adjusted HR 2.40 [95% CI 1.12-5.11]), developing metastatic disease (7.9% vs. 21%, adjusted HR 4.10 [95% CI 1.11-15.2]), and developing CRPC(4.0% vs. 14%, unadjusted HR 4.14 [95% CI 1.11-15.5]). CONCLUSIONS Patients with %fPSA≥15 were started on ADT earlier, and they progressed to CRPC and metastatic stage earlier. %fPSA of ≥15 in the setting of BCR after RP is an indicator of a more aggressive disease. Unlike in the diagnostic setting, a higher %fPSA portends a worse clinical outcome.