SPORT high-risk trial: A randomised feasibility study evaluating stereotactic prostate radiotherapy in high-risk localised prostate cancer with or without elective nodal irradiation

Abstract

Background: Prostate Cancer (PC) has a low alpha‐beta ratio, making it sensitive to hypofractionated radiotherapy. Stereotactic ablative radiotherapy (SABR) provides an opportunity for dose escalation beyond that achievable with conventional radiotherapy. Additionally, there is a lack of novel biomarkers in use in the management of localized PC. Method: Thirty men with high‐risk node‐negative PC (at least one of PSA > 20 ng/mL, T3a, Gleason score ≥ 4 + 3) will be randomized on a 1:1 basis to receive SABR to the prostate (P) and proximal seminal vesicles (SV) alone (36.25 Gy/5#) or to the addition of elective pelvic nodal irradiation (ENI) (25 Gy/5#). All men will be treated using a volumetric arc therapy solution with intra‐prostatic fiducial markers, a prostate‐rectal spacer device and cone‐beam CT‐based image‐ guidance. Results: The primary objective of this study is to demonstrate the feasibility of performing a randomised trial comparing P/SV SABR to the addition of ENI SABR in men with high‐risk localised PC. This will be measured via distinct endpoints: adequate recruitment rate (30 patients in 24 months), number of plans delivered as planned and on schedule, and quantification of acute toxicity to enable calculation of the sample size for a subsequent Phase II trial (CTCAE v4.03). Secondary objectives include quantification of late toxicity and quality of life scores and assessment of PC outcomes post‐SABR. Tertiary and exploratory outcomes include the biobanking of clinically annotated tissue, a health economic analysis, assessment of multiple biomarker candidates, measurement of fatigue, and assessment of the impact of prostate spacer placement. Conclusion: SABR provides scope for dose escalation in men with high‐risk localized PC. The role of ENI has not been determined. Furthermore, this trial offers an additional opportunity for novel biomarker investigation in localized PC.