Salvage Radiation Therapy Following Radical Prostatectomy. A National Danish Study

Background: The purpose of this observational cohort study was to evaluate the outcome and prognostic factors following salvage radiotherapy (SRT) in a consecutive national cohort.Material and methods: Between 2006 and 2010, 259 patients received SRT in Denmark. Patient- and cancer-related characteristics were retrospectively retrieved from patient charts. The primary end point was biochemical progression-free survival (b-PFS).Results: At the end of follow-up, 51% of the patients displayed a prostate-specific antigen (PSA) level<0.1ng/ml. The three-year b-PFS rate for the total cohort was 57.0%. Nearly half of the patients (44%) received androgen deprivation therapy (ADT) in combination with SRT. Positive surgical tumour margins (p=0.025) and ADT (p=0.001) were the only markers independently correlated with b-PFS. In patients who received SRT without ADT, both a pre-SRT PSA level0.5ng/ml (p=0.003) and pathological tumour stage T1-T2 (p=0.036) independently correlated with b-PFS. Moreover, a duration between radical prostatectomy (RP) and SRT 29 months (p=0.035) independently correlated with b-PFS in patients treated with ADT in combination with RT.Conclusions: In patients treated for biochemical failure after RP, positive surgical tumour margins and PSA levels 0.5ng/mL at the time of SRT were associated with a favourable outcome. Despite less favourable tumour characteristics, patients receiving SRT and ADT demonstrated improved b-PFS, and in particular, patients with PSA levels>0.2 ng/ml benefitted from additional ADT.