Biochemical and clinical outcomes after high-dose salvage radiotherapy as monotherapy for prostate cancer

Purpose To retrospectively evaluate the role of high-dose salvage radiotherapy (SRT) alone with regard to biochemical and clinical outcomes in patients with biochemical failure (BF) after radical prostatectomy (RP). Methods Between January 2003 and August 2011, 168 hormone-naïve localized prostate cancer patients received SRT alone for post-RP BF in a single institution and were retrospectively analyzed. Multivariate analysis was performed to determine the independent prognostic impact of clinical factors on biochemical and clinical outcomes [biochemical relapse-free survival (bRFS), clinical relapse-free survival (cRFS), cancer-specific survival (CSS) and overall survival (OS)]. Results Median follow-up was 54 months. Actuarial bRFS, cRFS, CSS and OS at 5 years were, respectively, 64, 86.2, 94.5 and 96.3 %. On multivariate analysis, nadir PSA (nPSA) after SRT was significantly associated with bRFS (HR 15, p = 0.001) and cRFS (HR 9, p = 0.001), while CSS was associated with RT dose (≥70 Gy; HR 1.9 p = 0.023), pre-RT PSA (<1.5 vs. ≥1.5 ng/mL; HR 1.3, p = 0.008) and age (>75 years; HR 1.2, p = 0.05). OS was significantly correlated with pre-SRT PSA (linear correlation; HR 1.1, p = 0.023) and age (<75 vs. ≥ 75 years; HR 1.1, p = 0.026). Conclusions Effective biochemical and clinical control rates may be safely achieved administering SRT with high doses (≥72 Gy) and using conformal techniques, especially in older patients presenting with lower pre-SRT PSA values. A lower nPSA after SRT predicts for better 5 years bRFS and cRFS rates.