Salvage Radiation For Biochemical Failure Following Radical Prostatectomy: Improved Outcomes With Early Treatment

Purpose/Objective(s)While salvage radiation therapy (SRT) to the prostate fossa has been shown to be most effective when Prostate-Specific Antigen (PSA) levels are low, the optimal PSA for salvage treatment remains unknown. The 2013 ASTRO/AUA Guideline states SRT should be administered to post-radical prostatectomy patients “at the earliest sign of PSA recurrence and ideally before PSA rises to 1.0 ng/mL.” We hypothesized that for patients with biochemical failure after radical prostatectomy, the lower the PSA level at time of referral for SRT the better the biochemical control.Materials/MethodsWe conducted a retrospective review of 229 patients with biochemical failure after radical prostatectomy under a Helsinki committee approved database. Between November 2002 and July 2013, patients were treated with salvage radiation using a mean bioequivalent radiation dose of 71 Gy (range 64-83 Gy), 3D conformal planning and 3D treatment techniques (including IMRT and VMAT), EORTC guidelines for the prostate fossa volume (beginning 2007) and Image Guidance with KV/KV imaging and cone beam CT (beginning 2008). Primary outcome was defined as biochemical recurrence free survival, clinical progression free survival and hormonal therapy free survival. 60-month probabilities of survival were estimated using the Kaplan Meier method, univariate analyses were conducted using log-rank tests and univariate predictors with p value ≤ .25 were considered using a Cox multivariate proportional-hazards model.ResultsMedian follow-up time was 50 months. Overall, patients receiving treatment with PSA values of < 0.3 ng/mL had the best 60-month biochemical control (87% n = 66), patients with PSA values between 0.3 ng/mL and 0.7 ng/mL had intermediate control (70% n = 94) and patients with PSA values > .7 ng/mL had the least favorable control (47% n = 69), p-value .7 ng/mL had the least favorable control (47% n = 69), p-value .7 ng/mL had the least favorable control (47% n = 69), p-value