3182 - PSA Reduction as Predictor of Biochemical Relapse in Low and Favorable Intermediate Prostate Cancer Treated with Radical Radiotherapy
Presenter(s)
A. G. Allegra1, L. Nicosia2, A. Molinari3, C. De-Colle1, C. Fierro3, N. Giaj-Levra1, F. Giannetti3, C. Menichelli3, C. Orsatti1, G. Pastore3, E. Pastorello1, F. Ricchetti1, M. Rigo1, A. Romei1, P. Zuccoli3, A. Fanelli3, and F. Alongi1,4; 1Department of Advanced Radiation Oncology, IRCSS "Sacro Cuore Don Calabria Hospital" Cancer Care Center, Negrar di Valpolicella (VR), Italy, 2Department of Advanced Radiation Oncology, IRCCS Sacro Cuore Don Calabria Hospital, Cancer Care Center, Negrar di Valpolicella, Italy, 3Radiotherapy Department, Ecomedica Poliambulatorio Ergéa Group, Empoli (FI), Italy, 4University of Brescia, Brescia, Italy
Purpose/Objective(s): Radiation therapy (RT) is standard treatment for localized prostate cancer (PCa). Prostate-specific antigen (PSA) kinetics, particularly PSA reduction (PSAr) after RT, are emerging as significant prognostic indicators for biochemical control. This retrospective multi-institutional study explores the correlation between PSAr and biochemical relapse-free survival (BRFS). This retrospective multi-institutional study explores the correlation between PSAr and biochemical relapse-free survival (BRFS).
Materials/Methods: 251 low-to-intermediate risk PCa patients treated with RT only were analyzed. Isoeffective RT schedules were: 39 fractions x2 Gy, 28x2.55 Gy, 16x3.5 Gy, 5x7 Gy. Main objective was BRFS, defined as the time from PSA nadir (PSAn) to PSAn plus 2 ng/ml. PSAr was defined as the percentage of total PSA reduction from baseline. The optimal PSAr cut-off value was defined as 90%. Patients were stratified by PSAr, baseline PSA, Gleason Score (GS), and RT schedules.
Results: GS was 3+3 in 120 (48%) patients and 3+4 in 131 (52%) patients. After a median follow-up of 36 months (30-48), 2 and 5-year BRFS were 97.3% and 95.2%, respectively, in patients with PSAr =90% and 89.5%, 61.5% in patients with PSAr<90% (p=0.00). In the responder population, median time to PSAr 90% was 24 months and the median time to PSAn was 28.7 months (20-38). At univariate and multivariate analyses, PSAr was the only significant predictor of BRFS [HR 6.519 (95% IC 1.9-22.2), p=0.003].
Conclusion: PSAr could be a reliable prognostic factor for long-term biochemical control. This study underscores the potential of PSAr as a tool for risk stratification and personalized follow-up strategies in PCa management.