Prognostic factors after salvage radiotherapy alone in patients with biochemical recurrence after radical prostatectomy

Objectives: To evaluate the oncological outcome and to assess prognostic factors of salvage radiotherapy alone in patients with biochemical recurrence after radical prostatectomy. Methods: We reviewed our single institution, prospectively maintained database of 2043 patients who underwent radical prostatectomy between September 1995 and Dcember 2011. In this cohort, 149 patients who developed biochemical recurrence after radical prostatectomy and received salvage radiotherapy alone after pelvic magnetic resonance imaging were included. Three-dimensional conformal radiotherapy or intensity-modulated radiotherapy was delivered with a median dose of 70.0 Gy (66.0-78.0 Gy) or 67.2 Gy (64.8-70.0 Gy). Kaplan-Meier and Cox regression analyses were carried out. Results: With a median follow up of 82 months (range 20-153 months), 55 patients (36.9%) failed salvage radiotherapy. The 5-year salvage radiotherapy failure-free probability was 53.6%. On multivariate analysis, pre-salvage radiotherapy prostate-specific- antigen ≥1.0 ng/mL (P = 0.003, hazard ratio 3.592, 95% confidence interval 1.522-8.579), pathological stage ≥T3a (P = 0.004, hazard ratio 2.261, 95% confidence interval 1.290-3.833), pathological Gleason score ≥7 (P = 0.018, hazard ratio 5.501, 95% confidence interval 1.577-21.221), prostate-specific antigen doubling time <12 months (P = 0.014, hazard ratio 2.243, 95% confidence interval 1.177-4.275) and no visible lesion on pelvic magnetic resonance imaging (P = 0.016, hazard ratio 2.068, 95% confidence interval 1.268-3.501) were independent prognostic factors of salvage radiotherapy failure after radical prostatectomy. Conclusions: Pre-salvage radiotherapy prostate-specific antigen ≥1.0 ng/mL, pathological stage ≥T3a, pathological Gleason score ≥7, prostate-specific antigen doubling time <12 months and no visible lesion on pelvic magnetic resonance imaging are prognostic factors of salvage radiotherapy failure after radical prostatectomy. We should consider additional treatment in patients with these factors for favorable outcomes.