Evaluation of the Clinical Utility of Online Adaptive Radiotherapy in Bladder Cancer (BLADAPT-GETUG V11)

Trimodal therapy (TMT) consisting of transurethral resection of bladder tumors followed by radiotherapy and chemotherapy is a therapeutic alternative in patients with Muscle-Infiltrating Bladder Cancer who are inoperable or refuse surgery. One of the main challenges of TMT is the planning and delivery of radiation therapy. Indeed, the bladder is a mobile hollow organ subject to repletion, with variations in size and shape during and between radiotherapy sessions. Standard radiotherapy techniques require large planning target volume margins around the bladder, which can be responsible for irradiation of a large volume of large and small bowel with grade 2 and 3 toxicities. Adaptive radiotherapy allows for the generation of a treatment fraction personalized to a patient\'s anatomical modification with margin reduction and improves the dosimetric quality of the delivered plans. The hypothesis is that this improvement results in radiation-induced toxicity improvement.