Adaptive Radiotherapy in Bladder Cancer: Phase II Results from the RAIDER II Trial

Cancer research · Bladder cancer

Adaptive radiotherapy is safe and feasible for muscle‑invasive bladder cancer, with a low rate of grade 3 toxicity and encouraging disease control.

The RAIDER II trial is a multicentre, randomised phase II study assessing adaptive radiotherapy (ART) techniques for muscle‑invasive bladder cancer. Three arms were compared: standard whole‑bladder radiotherapy, tumor‑focused boost with standard dose (SART arm) and the same boost with a 15 % dose escalation. Ninety‑seven % of patients received concomitant chemotherapy, most commonly 5‑FU/mitomycin. ART was delivered with daily cone‑beam CT and a three‑plan ‘plan‑of‑the‑day’ workflow. The primary endpoint was incidence of ≥grade 3 toxicity. ART achieved a 1.7 % grade‑3 toxicity rate, well below the pre‑specified 20 % threshold, and comparable to the standard arm. Disease‑control outcomes, including bladder‑intact event‑free survival, were numerically higher in the high‑dose arm (71.7 % vs. 66 %) but not statistically significant. Quality of life remained stable across groups. The study demonstrates ART is safe, tolerable, and feasible in a routine clinical setting, suggesting a potential shift toward bladder‑preserving radiotherapy strategies.

Improving precision in bladder radiotherapy may enhance organ preservation, reduce radiation‑related morbidity, and potentially improve oncologic outcomes in patients with muscle‑invasive bladder cancer.

Evidence level: Sejtvonalas. Laboratóriumi sejtekben vizsgálták.

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