CyberKnife stereotactic radiotherapy for isolated recurrence in the prostatic bed

Purpose: To report a clinical experience of stereotactic body radiation therapy (SBRT) for isolated recurrence in the prostatic bed from prostate cancer. Materials and methods: Between November 2011 and November 2013, 16 patients were treated with SBRT for a macroscopic isolated recurrence of prostate cancer in the prostatic bed. All patients were initially treated with radical prostatectomy, and half of them also received radiotherapy. Two schedules of SBRT were used: 30 Gy in 5 fractions in previously irradiated patients, 35 Gy in five fractions in radiotherapy-naïve patients. Results: At a median follow-up of 10 months (range 2–21 months), a significant biochemical response was found in all but one patient. At imaging evaluation, no local progression was noted: 10 patients showed partial response while four stable disease. At the moment of analysis, all 16 patients were alive. Seven of them experienced distant relapse, while nine maintained biochemical control, with no further therapy. Median time to relapse was 9.3 months (range 3–15.2 months). The treatment was well tolerated: One patient experienced G2 acute genitourinary and gastrointestinal toxicity. Conclusions: Our experience shows that SBRT with CyberKnife for isolated nodal relapse is a safe and well-tolerated treatment.