Salvage Radiosurgery After Brachytherapy for Locally Recurrent Prostate Cancer With Real-Time Adaptive Motion Management Using Previously Implanted Brachytherapy Seeds as Fiducial Markers

Locally recurrent prostate cancer after radiotherapy is a difficult clinical scenario. Focal therapy with stereotactic body radiation therapy (SBRT) is a promising treatment option. In this case report, we present the case of a male patient who underwent low dose rate (LDR) brachytherapy many years ago and experienced a prostate-specific membrane antigen positron emission tomography (PSMA PET) avid local recurrence of prostate cancer with rising prostate-specific antigen (PSA). He was able to undergo salvage CyberKnife (Accuray, Madison, WI) robotic radiosurgery without the need for additional fiducial marker placement by tracking previously implanted brachytherapy seeds. Treatment of 40 Gy in five fractions to the PET avid tumor gross tumor volume (GTV) and 35 Gy in five fractions to the planning target volume (PTV) was successfully delivered with minimal toxicity. The patient tolerated therapy well with excellent urinary and sexual functioning and declining PSA at the last follow-up.