Salvage robotic SBRT for local prostate cancer recurrence after radiotherapy: preliminary results of the Oscar Lambret Center

Background: Currently, there is no standard option for local salvage treatment for local prostate cancer recurrence after radiotherapy. Our objective was to investigate the feasibility and efficiency of Robotic Stereotactic Body Radiation Therapy (SBRT) in this clinical setting. Methods/materials: We retrospectively reviewed patients who were treated at our institution with SBRT for local prostate cancer recurrence after External Beam Radiation Therapy (EBRT) or brachytherapy. Multidisciplinary staff approved the treatment, and recurrence was biopsy-proven when feasible. A dose of 36 Gy was prescribed in six fractions. Treatment was delivered every other day. Results: Between August 2011 and February 2014, 23 patients were treated with SBRT for intra-prostate cancer recurrence with a median follow up of 22 months (6 to 40). Twenty patients had biopsy-proven recurrence. For 19 patients, EBRT was the initial treatment and in four patients, brachytherapy was the initial treatment; the median relapse-time from initial treatment was 65 months (28 to 150). At relapse, 10 patients had an extra-capsular extension. Fourteen patients were treated with androgen deprivation that could be stopped after a median of 1 month after SBRT (range 0-24). A PSA decrease occurred in 82.6% of the patients after SBRT. The 2-year disease-free survival and overall survival rates were 54 and 100%, respectively. Disease progression was observed for nine patients (39.1%) (five local, three metastatic and one nodal progression) after a median of 20 months (7-40 months). The median nadir PSA was 0.35 ng/ml and was achieved after a median of 8 months (1 to 30) after treatment. We observed no grade 4 or 5 toxicity. Two patients presented with grade 3 toxicities (two Cystitis and one neuralgia). Other toxicities included urinary toxicities (five grade 2 and nine grade 1) and rectal toxicities (two grade 2 and two grade 1). Conclusion: SBRT for local prostate cancer recurrence seems feasible and well tolerated with a short follow up. Prospective evaluation is needed.