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NOT YET RECRUITING
NCT07830511
PHASE3

RIsk aDapted Stereotactic Radiotherapy vs. standarD of Care Radiotherapy in Patients With Prostate Cancer in the Adjuvant or saLvage sEtting With or Without Lymph Node Irradiation (RIDDLELN) - A Phase III Trial

Sponsor: Robert Förster

View on ClinicalTrials.gov

Summary

The goal of this clinical trial is to determine whether stereotactic body radiotherapy (SBRT) delivered in five fractions is non-inferior to standard-of-care mildly hypofractionated radiotherapy in terms of patient-reported quality of life in adults with prostate cancer who require adjuvant or salvage radiotherapy after radical prostatectomy. The trial includes patients with or without a macroscopic recurrence in the prostate bed and allows irradiation of the regional lymphatic drainage when clinically indicated. The main questions it aims to answer are: * Is SBRT non-inferior to standard-of-care radiotherapy regarding urinary (GU) quality of life, measured by the change in the EPIC-26 GU domain score from baseline to 24 months after radiotherapy? * Is SBRT non-inferior to standard-of-care radiotherapy regarding bowel (GI) quality of life, measured by the change in the EPIC-26 GI domain score from baseline to 24 months after radiotherapy? Researchers will compare SBRT delivered as 6 Gy × 5 fractions to the prostate bed with standard-of-care radiotherapy delivered as 2.625 Gy × 20 fractions (total dose 52.5 Gy) to determine whether the substantially shorter SBRT treatment provides non-inferior patient-reported urinary and bowel outcomes. When clinically indicated, treatment of the lymphatic drainage and a simultaneous integrated boost to macroscopic recurrence or involved lymph nodes may also be delivered. Participants will: * Be randomly assigned in a 1:1 ratio to receive either five-fraction SBRT or 20-fraction standard-of-care radiotherapy. * Receive radiotherapy to the prostate bed, with additional irradiation of the regional lymphatic drainage and/or a boost to macroscopic disease or involved lymph nodes when clinically indicated. * Complete questionnaires assessing quality of life, urinary symptoms, and sexual function, including EPIC-26, IPSS, and IIEF-5. * Undergo clinical assessments, PSA measurements, assessment of treatment-related adverse events, and radiological imaging when clinically indicated. * Attend follow-up assessments at 3, 6, 12, 18, and 24 months after radiotherapy and then annually for up to 5 years. A total of 206 participants are planned for the trial. In addition to the primary quality-of-life outcomes, researchers will assess acute and late toxicity, biochemical recurrence-free survival, progression-free survival, time to further anti-cancer therapy, prostate cancer-specific survival, and overall survival.

Key Details

Gender

MALE

Age Range

18 Years - Any

Study Type

INTERVENTIONAL

Enrollment

206

Start Date

2026-09-01

Completion Date

2034-09-01

Last Updated

2026-09-21

Healthy Volunteers

No

Interventions

RADIATION

Stereotactic body radiotherapy (SBRT) to the prostate bed

SBRT to the prostate bed, 6 Gy per fraction in 5 fractions on consecutive working days (EQD2 64.3 Gy at α/β 1.5), completed within approximately one week. Optional simultaneous integrated boost (SIB) up to 6.8 Gy per fraction over 5 fractions to a macroscopic recurrence. If treatment of the lymphatic drainage is indicated (e.g. Roach score above 20% and/or node-positive disease), SIB of 5 Gy per fraction over 5 fractions to the lymphatic drainage, with involved nodes boosted up to 6.8 Gy per fraction over 5 fractions. Delivered as image-guided intensity-modulated radiotherapy. Administered to the experimental arm.

RADIATION

Standard-of-care radiotherapy (SOC) to the prostate bed

SOC radiotherapy to the prostate bed, 2.625 Gy per fraction in 20 fractions (total 52.5 Gy; EQD2 61.95 Gy) on consecutive working days, over approximately four weeks. Optional simultaneous integrated boost (SIB) up to 3 Gy per fraction over 20 fractions to a cumulative total of 60 Gy to a macroscopic recurrence. If treatment of the lymphatic drainage is indicated (e.g. Roach score above 20% and/or node-positive disease), SIB of 2.2 Gy per fraction over 20 fractions to the lymphatic drainage, with involved nodes boosted up to 3 Gy per fraction over 20 fractions. Delivered as image-guided intensity-modulated radiotherapy. Administered to the control arm.