Salvage stereotactic body radiation therapy following definitive cryotherapy

Abstract Purpose Whole gland cryotherapy is a guideline approved definitive treatment for localized prostate cancer, and is being explored for partial gland ablation. However, there's a little data regarding management of cryotherapy failures. Stereotactic body radiation therapy (SBRT) is a novel and well-established method of primary treatment for prostate cancer. Here we review salvage SBRT following cryotherapy failures. Methods and Materials A large database of patients treated with definitive SBRT was interrogated to identify those who underwent primary cryotherapy. All patients were determined to have progressive disease based on a rising PSA and/or post-cryotherapy biopsy. All patients were treated with SBRT over 5 treatment fractions using a robotic radiosurgical platform. Baseline cryotherapy characteristics and pre-and post-treatment EPIC questionnaires were analyzed. Acute and late toxicity was evaluated using the CTCAE version 5.0. Cancer outcomes following salvage SBRT were stratified by disease and treatment characteristics. Results A total of 51 patients were identified who underwent cryotherapy followed by salvage SBRT. The majority (47%) were found to have intermediate risk disease at the time of SBRT salvage and most commonly were treated with 3500 cGy in 5 fractions to the prostate and seminal vesicles. Only one grade 3+ toxicity was identified. Patient-reported quality of life metrics following SBRT salvage followed prior patterns observed in the de novo SBRT setting. With a median follow up of 40 months, 76% of the cohort demonstrated disease control. Median time to prostate cancer recurrence was 57.5 months and was predominantly seen in patients with underlying high-risk disease. Conclusions This is largest cohort of patients treated with any radiotherapy salvage following cryotherapy and the first institution to report SBRT salvage. Salvage SBRT following cryotherapy results in low rates of high-grade toxicity, acceptable changes in patient-reported quality of life, and durable rates of long-term oncological control.