From clinical trials to clinical practice: patterns of practice survey on prostate SABR in Australia and New Zealand

Purpose: Prostate stereotactic ablative body radiotherapy (SABR) is now a standard-of-care radiation therapy option for prostate cancer based on high-level clinical trial evidence. As part of the Australia and New Zealand (ANZ) prostate SABR guideline development process, the Royal Australian and New Zealand College of Radiologists has commissioned a pattern-of-practice survey on contemporaneous prostate SABR practice. Methods and Materials: We conducted a cross-sectional survey among ANZ genitourinary radiation oncologists (ROs), focusing on patient selection, contouring, treatment planning, and delivery of prostate SABR. Results: A total of 53 ROs across ANZ responded to the survey (response rate: 28%). Of the 41 ROs currently offering prostate SABR, 95%, 90%, 35%, 5%, and 0% offer prostate SABR as standard-of-care options to individuals with favorable intermediate risk, unfavorable intermediate risk, favorable high risk (NINJA/ TROG18.01 trial eligible), very high risk, and node-positive prostate cancer, respectively. Most ROs (86%) routinely use fiducial markers. All ROs routinely request planning magnetic resonance imaging for contouring. Clinical target volume contouring ranged from prostate alone (26%) to prostate plus proximal 1 cm of the seminal vesicles (81%). Planning target volume margins ranged from 3 to 5 mm. An anisotropic 5 mm margin with 3 mm posteriorly was most common (56%). Nineteen (45%) ROs provide a focal boost to the intraprostatic lesion. The most common dose fractionation was 36.25 Gy to the planning target volume and 40 Gy to the clinical target volume over 5 fractions, delivered as 2 (50%) to 3 fractions (76%) per week. The majority of ROs offer prostate SABR on standard computed tomography-linear accelerator (LINAC) (88%), with several ROs also treating patients with CyberKnife (10%) and magnetic resonance-LINAC (5%). Of the ROs who use standard computed tomography-LINAC, 84% use intrafraction motion monitoring. Twelve (23%) ROs do not offer prostate SABR. The main barrier cited was a lack of expertise (42%). Conclusions: This ANZ-wide prostate SABR pattern-of-practice survey demonstrated some variations in practice, providing contemporary insight into how prostate SABR is delivered across ANZ and highlighting barriers to wider adoption.