PP02 Presentation Time: 9:10 AM: Salvage Prostate Brachytherapy in Radiorecurrent Prostate Cancer: An International Delphi Consensus Study

Abstract

<h3>Purpose</h3> Local recurrences after previous radiotherapy (RT) are increasingly being identified with increasing use of molecular imaging in biochemically recurrent prostate cancer. Salvage prostate brachytherapy (BT) is an effective and well tolerated treatment option for radiorecurrent prostate cancer. While supported by multiple prospective studies, limited comparative data exists to guide optimal patient selection and treatment technique. We sought to generate international consensus statements on the use and preferred technical considerations for salvage prostate BT. <h3>Materials and Methods</h3> International experts in salvage prostate BT were invited (n=34) to participate. A three-round modified Delphi technique was utilized, with questions focused on patient- and cancer-specific criteria, type and technique of BT, and follow-up after salvage. An a priori threshold for consensus of ≥ 75% was set, with a majority opinion being set at ≥ 50%. <h3>Results</h3> Thirty international experts agreed to participate, and the response rates were 100% (30/30), 93.3% (28/30) and 100% (30/30) for the first, second and third rounds of the survey respectively. Consensus was achieved for 56% (18 of 32) statements. Consensus was achieved in several areas of patient selection, including: 1) A minimum of 2-3 years from initial RT and consideration of salvage BT; 2) MRI and PSMA PET should be acquired prior to salvage; 3) Both a targeted and systematic prostate biopsy should be performed; 4) Salvage BT can be considered after any initial RT technique; and 5) Any Gleason Score at recurrence could be considered for salvage. Several areas did not reach consensus and were controversial: 1) Cut off for maximum T stage and PSA at time of salvage; 2) Whether ADT should be used with salvage BT (and duration); 3) Whether it was appropriate to combine local salvage with SBRT for oligometastatic disease and 4) Whether salvage BT may be repeated more than once. More than 50% of respondents preferred High Dose-Rate salvage BT, and indicated that both focal and whole gland salvage could be appropriate depending on the clinical situation. There was no single preferred dose fractionation for salvage prostate BT. <h3>Conclusions</h3> These findings will inform development of an international expert consensus statement for salvage prostate BT. Consensus was achieved on 56% of statements, though several controversial areas were identified. While our results highlight there is no single preferred approach for salvage BT, areas of controversy will be relevant for the design of future prospective studies and clinical trials of salvage BT.