HYBRIDA Multicentre Randomised Phase II Study of HYpofractionated Bladder Radiotherapy With or Without Image Guided aDaptive Planning

OBJECTIVES: Primary To assess whether adaptive radiotherapy techniques when delivered at multiple centres can lead to a reduction in the level of acute non-genitourinary (GU) toxicity experienced by patients with muscle invasive bladder cancer unsuitable for daily radical radiotherapy. Secondary Establish the local disease control rates of hypofractionated bladder radiotherapy as measured at 3 months Assess time to local disease progression Assess the overall survival time of patients who have received hypofractionated radiotherapy. Investigate the control rate of presenting symptoms, the effect of hypofractionated treatment on late radiotherapy side effects and patient reported outcomes. To establish the proportion of fractions benefiting from adaptive planning. OUTLINE: This is a multicentre randomised Phase II study in patients with muscle invasive bladder who are not suitable for cystectomy or daily radiotherapy. All patients will be planned to receive six 6Gray (Gy) fractions of image guided radiotherapy delivered weekly (total dose: 36Gy) and will be randomised to standard or adaptive planning. Participants allocated to the standard planning group will have one radiotherapy plan generated and this will be used to deliver all 6 treatments, with a cone beam CT scan prior to treatment delivery which can be used by the local investigator to adjust treatment delivery according to local practice. Participants allocated to adaptive planning will have three radiotherapy plans generated; small, medium and large. A cone beam CT taken prior to each treatment delivery will be used to select the most appropriate plan of the day. Patients are followed up in terms of the trial up to 24 months, after this time only basic routine follow-up data will be collected. PROJECTED ACCURAL: The aim is to recruit 62 participants, 31 to each treatment allocation.