Researchers have made strides in refining radiotherapy for muscle-invasive bladder cancer, demonstrating the potential of personalized approaches to improve treatment outcomes and reduce side effects. A recent study published in European Urology highlights the benefits of adaptive radiotherapy, where treatment plans are tailored to the individual patient's anatomy.
The Phase 2 RAIDER trial, conducted across the U.K., Australia, and New Zealand, explored the feasibility and safety of adaptive radiotherapy in 345 patients with muscle-invasive bladder cancer. Led by Professor Robert Huddart from The Institute of Cancer Research, London, the study compared standard radiotherapy with adaptive methods, including dose-escalated adaptive radiotherapy (DART).
Adaptive Radiotherapy: A Personalized Approach
Traditional radiotherapy often employs a 'one size fits all' approach, delivering the same dosage in each session. However, the bladder's shape and position can vary, complicating targeted treatment. Adaptive radiotherapy addresses this challenge by creating multiple treatment plans (small, medium, and large) and selecting the most appropriate plan based on the bladder's size and position at each session.
Professor Emma Hall, Co-Director of the Clinical Trials and Statistics Unit at The Institute for Cancer Research, London, noted, "As medical technologies continue to improve, it means that we can investigate delivering more complicated and personalised forms of radiotherapy to treat certain cancers."
Key Findings from the RAIDER Trial
The RAIDER trial revealed that adaptive radiotherapy, particularly DART, led to fewer serious long-term side effects compared to standard radiotherapy. Notably, there was no evidence that higher radiation doses in the DART group resulted in worse side effects. The two-year overall survival was 80% with DART, comparable to 77% for patients treated with standard whole-bladder RT (WBRT) or standard-dose adaptive RT (SART).
Robert Huddart, MBBS, PhD, of the Royal Marsden Hospital in London, stated that the image-guided adaptive strategy enabled radiotherapy dose escalation to over 86% of patients' bladder tumors without significant increase in toxicity.
Addressing Challenges and Future Directions
Despite the promising results, challenges remain in standardizing bladder volume during treatment. As Krishnan Patel, MD, of the National Cancer Institute's Center for Cancer Research, explained, variations in bladder volume can affect the interface between the bladder and surrounding organs, influencing radiation delivery. The study protocol involved standardizing liquid intake to maintain consistent bladder volume, but individual variations persist.
Further studies are planned to evaluate the effectiveness of adaptive radiotherapy in improving cancer control and patient outcomes. Dr. Hattie Brooks, Research Information Manager at Cancer Research UK, expressed enthusiasm for the potential of adaptive radiotherapy to reduce side effects and improve the lives of people treated for bladder cancer.
Trinanjan Basu, MD, of HCG Cancer Center in Borivali, India, emphasized that a strict contouring, planning, and image-guided adaptive RT protocol remains cornerstone for this approach and should be investigated and explored further.
