Clinical outcomes after salvage radiotherapy without androgen deprivation therapy in patients with persistently detectable PSA after radical prostatectomy: results from a national multicentre study.

Purpose: To assess oncologic outcomes after salvage radiotherapy (SRT) without androgen deprivation therapy (ADT) in patients with persistently detectable PSA after radical prostatectomy (RT).
Methods: Two hundred and one patients who failed to achieve an undetectable PSA received SRT without ADT. The primary endpoint was failure to SRT that was defined by clinical progression or use of second-line ADT. Clinicopathological parameters, 6-week PSA level, PSAV and pre-SRT PSA levels were assessed using time-dependent analyses.
Results: Median postoperative 6-week PSA and pre-SRT PSA levels were 0.25 and 0.48 ng/mL, respectively. Median time between surgery and SRT was 7 months. Failure to SRT was reported in 42.8 % of cases with the need for second-line ADT in 26.9 % of cases. Pre-SRT PSA was strongly correlated with postoperative 6-week PSA (p < 0.001) but not with PSAV. The risk of SRT failure was increased by threefold in case of Gleason score 8-10 (p = 0.036) or pT3b cancer (p = 0.006). Risk group classification based on these prognostic factors improved SRT failure prediction. Survival curves confirmed that 5-year ADT-free survival rates were significantly influenced by PSAV (p = 0.002) and pre-SRT PSA (p = 0.030).
Conclusions: In patients with persistently detectable PSA after RP and selected for local salvage treatment, SRT offers good oncologic clinical outcomes. The most powerful pathologic predictive factors of SRT failure include a pT3b stage, a Gleason score 8 or more cancer and high PSAV and pre-SRT PSA levels. Patients having a high PSAV >0.04 ng/mL/mo would be potentially better candidates for a systemic therapy due to a high SRT failure rate.