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.