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Reduced Length of ADT and ARTA With XRT in High-Risk Prostate Cancer (RELAX): A Randomised Controlled Trial

Murthy V, Maitre P, Priya S, Dhingra S, Dhanawat A, Shah M, Bhattacharya K, Adepu A et al.

Clinical oncology (Royal College of Radiologists (Great Britain)), 2026

206 participants

Abstract

Aim: To assess the efficacy of a short, intensified regimen of androgen deprivation therapy (ADT) and androgen receptor-targeted agent (ARTA) with curative-intent external beam radiotherapy (XRT) for high-risk prostate cancer (HRPCa) staged with prostate specific membrane antigen (PSMA) imaging.

Materials and methods: The RELAX (Reduced Length of ADT and ARTA with XRT in high-risk prostate cancer) trial is a multicentre, phase II randomised non-inferiority trial comparing 9 months of ADT and 6 months of ARTA against the standard 24-month ADT, with definitive dose-escalated hypofractionated pelvic radiotherapy for PSMA-staged non-metastatic HRPCa. The primary endpoint is 5-year disease-free survival (DFS), defined from randomisation to first biochemical or clinico-radiological recurrence or any-cause death. Secondary endpoints include biochemical failure-free survival, metastasis-free survival, overall survival, testosterone recovery, treatment-related adverse effects, and patient-reported outcomes. Participants are monitored with serial serum PSA and testosterone levels, CTCAE and PRO-CTCAE assessments, and PSMA-PETCT at recurrence. The non-inferiority margin is set at 10% absolute difference from an expected 5-year DFS of 85% in the standard arm, with intention-to-treat analysis. The trial is ethics board approved and funded by institutional intramural grant, and registered on clinicaltrials.gov (NCT06818682).

Results: The planned accrual of 206 participants commenced in…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 206 participants or records.

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