Study of Higher Dose MR-Guided Radiotherapy for Rectal Cancer Using Adaptive Treatment to Target Tumor Changes

What this Trial Is About

Researchers are evaluating a new approach to treat locally advanced rectal adenocarcinoma by increasing the dose of radiotherapy while using adaptive techniques to target the cancer more precisely. The study aims to see if this dose escalation can improve the chance of completely treating the cancer, known as complete pathological response, potentially allowing patients to avoid surgery and its long-term complications. The trial uses a novel MR-linac machine that combines MRI imaging with radiotherapy to adapt treatment daily based on tumor changes. Participants will receive a standard dose of 45Gy to the mesorectum and elective nodal areas, and 52.5Gy to the primary tumor area over 25 treatment sessions. From the second week of treatment, those with visible tumor may receive a boost dose up to 60Gy. The MR-linac allows for daily adjustments to the radiation plan, focusing treatment on the tumor while sparing healthy tissue. Non-adaptive treatments can be delivered using either the MR-linac or a CT-linac system. During the study, patients will undergo regular assessments including MRI scans, camera tests sigmoidoscopy, and patient-reported questionnaires to monitor side effects and tumor response. Researchers will track treatment completion rates on the MR-linac, gastrointestinal and genitourinary side effects, tumor recurrence, and pathological response over up to two years. The studys total participation includes the treatment period and long-term follow-up to evaluate safety and effectiveness of this adaptive, higher-dose radiotherapy approach.

Dose Escalated Radiotherapy for Rectal Cancers Using MR-guided Radiotherapy