Salvage radiation therapy after radical prostatectomy: survival analysis

To evaluate the outcome of patients treated with salvage radiotherapy after radical prostatectomy and to investigate the effects of independent predictors on survival.

From January 2000 to December 2015, 234 patients with biochemical/clinical recurrences after radical prostatectomy were submitted to salvage radiotherapy (SRT). One hundred and fifty-seven patients (67%) received three-dimensional (3D) conformal radiotherapy while 77 patients (33%) were treated with intensity-modulated radiotherapy (IMRT) or IMRT/image-guided radiotherapy by tomotherapy. The median RT dose to prostate bed was 70.2 Gy (range: 66-79 Gy). The investigated endpoints were biochemical relapse-free survival (BRFS), clinical relapse-free survival (CRFS), distant metastasis-free survival (DMFS), and prostate cancer-specific survival (PCSS). Different covariates were considered to investigate predictors of survival.

With a median follow-up of 117 months the BRFS, CRFS, DMFS and PCSS at 10 years were 54%, 84%, 90%, and 94%, respectively. In multivariate analysis (MVA), the pathological Gleason Score (pGS) was the most important factor affecting BRFS, CRFS, DMFS and PCSS (P<0.007, HR>1.55); pathological stage (pT) was predictor of BRFS (P=0.007, HR=1.7) and PCSS (P=0.02, HR=4.2), and the last prostate-specific antigen during follow-up was an important survival predictor of CRFS (P=0.004, HR=1.26) and PCSS (P<0.0001, HR=1.04). The time between surgery and the start of SRT was correlated with BRFS (P<0.0001, HR=0.987) and CRFS (P=0.047, HR=0.989). In univariate analysis (UVA), positive surgical margins at the prostatectomy specimen improved BRFS (P=0.01, HR=0.54), CRFS (P=0.05, HR=0.46) and DMFS (P=0.005, HR=0.13) after SRT.

At long-term follow-up, excellent outcome results of SRT on BRFS, CRFS, DMFS, and PCSS were obtained. Several prognostic factors such as pGS, pT and surgical margin status were found to be predictors of survival.