American Brachytherapy Society (ABS) rectoprostatic gel spacer consensus statement.

Purpose: This consensus statement provides recommendations based on expert opinion and best available evidence for the use of rectoprostatic gel spacers (RPS) in the setting of definitive radiation therapy (RT) for men with prostate cancer (PC) and the prevention and management of associated adverse events.

Materials and methods: The American Brachytherapy Society (ABS) assembled an expert panel of 11 physicians to review key aspects of RPS in the definitive treatment of PC with RT. After multiple iterations by the panel to refine key questions and statements regarding RPS utilization in PC RT, a Delphi consensus method was employed to generate consensus statements. A review of prospective and retrospective RPS studies in the setting of external beam RT (EBRT), brachytherapy (BT, including low dose rate (LDR) and high dose rate (HDR)), and combinations of EBRT and BT for treatment of PC was performed to complement the expert panel's recommendations, focused on indications, expected benefits, known risks, and insights on adverse event management.

Results: A total of eight key questions with a total of 27 subsections regarding RPS indications and adverse events were addressed by the panel. Following three anonymized survey iterations which included panel discussion meetings, consensus statements were reached for 24 of the 27 reviewed items. While the panel reached consensus in support of RPS for external beam photon RT, proton RT, and LDR BT monotherapy, the panel did not reach consensus on the use of RPS for HDR monotherapy or combination BT with EBRT. Consensus was reached in most cases for contraindications to RPS placement, except for scenarios involving tumor abutment of the neurovascular bundle (NVB). Consensus was reached for imaging indications, elements of informed consent, and management of rectal wall infiltration (RWI).

Conclusions: This consensus statement summarizes the current indications for RPS placement and the management of potential adverse events prior to proceeding with definitive RT for PC.