DIPPER trial protocol: A multi-centre, randomised trial of salvage radiotherapy versus surveillance for biochemical recurrence after radical prostatectomy (ANZUP 2002).

Abstract

Salvage radiation therapy and surveillance for low risk PSA recurrence have competing risks and benefits. The efficacy of early salvage radiation therapy to the prostate bed with or without pelvic lymph nodes compared to surveillance in patients with prostate specific antigen (PSA) recurrence following radical prostatectomy and no identifiable recurrent disease evident on prostate specific membrane antigen-positron emission tomography/computerised tomography (PSMA-PET/CT) is unknown. Dedicated Imaging Post-Prostatectomy for Enhanced Radiotherapy outcomes (DIPPER) is an open-label, multi-centre, randomised phase 2 trial. The primary endpoint is 3-year event-free survival, with events comprising one of PSA recurrence (PSA ≥0.2ng/mL higher than baseline), radiologic evidence of metastatic disease or initiation of systemic or other salvage treatments. Secondary endpoints include patient reported outcomes, treatment patterns, participant perceptions and cost-effectiveness. Eligible participants have PSA recurrence of prostate cancer following radical prostatectomy, defined by serum PSA 0.2-0.5ng/mL, deemed low risk according to modified European Association of Urology (EAU) biochemical recurrence risk criteria (ISUP Grade Group ≤2, PSA doubling time more than 12 months), with no definite/probable recurrent prostate cancer on PSMA-PET/CT.