PSMA-PET/CT-guided salvage radiotherapy in recurrent or persistent prostate cancer and PSA < 0.2 ng/ml
Nantia Solomonidou, Daphnie Germanou, Iosif Strouthos, Efstratios Karagiannis, Andrea Farolfi, Stefan A. Koerber, Jürgen Debus, Jan C. Peeken, Marco E. Vogel, Alexis Vrachimis, Simon K. B. Spohn, Mohamed Shelan, Daniel M. Aebersold, Anca‐Ligia Grosu, Francesco Ceci, Stephanie Kroeze, Matthias Gückenberger, Stefano Fanti, Claus Belka, George Hruby, Sophia Scharl, Thomas Wiegel, Peter Bartenstein, Christoph Henkenberens, Louise Emmett, Nina-Sophie Schmidt-Hegemann, Konstantinos Ferentinos, Constantinos Zamboglou
Abstract
PURPOSE: The purpose of this retrospective, multicenter study was to assess efficacy of PSMA-PET/CT-guided salvage radiotherapy (sRT) in patients with recurrent or persistent PSA after primary surgery and PSA levels < 0.2 ng/ml. METHODS: The study included patients from a pooled cohort (n = 1223) of 11 centers from 6 countries. Patients with PSA levels > 0.2 ng/ml prior to sRT or without sRT to the prostatic fossa were excluded. The primary study endpoint was biochemical recurrence-free survival (BRFS) and BR was defined as PSA nadir after sRT + 0.2 ng/ml. Cox regression analysis was performed to assess the impact of clinical parameters on BRFS. Recurrence patterns after sRT were analyzed. RESULTS: The final cohort consisted of 273 patients; 78/273 (28.6%) and 48/273 (17.6%) patients had local or nodal recurrence on PET/CT. The most frequently applied sRT dose to the prostatic fossa was 66-70 Gy (n = 143/273, 52.4%). SRT to pelvic lymphatics was delivered in 87/273 (31.9%) patients and androgen deprivation therapy was given to 36/273 (13.2%) patients. After a median follow-up time of 31.1 months (IQR: 20-44), 60/273 (22%) patients had biochemical recurrence. The 2- and 3-year BRFS was 90.1% and 79.2%, respectively. The presence of seminal vesicle invasion in surgery (p = 0.019) and local recurrences in PET/CT (p = 0.039) had a significant impact on BR in multivariate analysis. In 16 patients, information on recurrence patterns on PSMA-PET/CT after sRT was available and one had recurrent disease inside the RT field. CONCLUSION: This multicenter analysis suggests that implementation of PSMA-PET/CT imaging for sRT guidance might be of benefit for patients with very low PSA levels after surgery due to promising BRFS rates and a low number of relapses within the sRT field.