MRI Simulation-guided Boost in Short-course Preoperative Radiotherapy for Unresectable Rectal Cancer

Improvements in downstaging are required when using preoperative chemoradiation for unresectable rectal cancer. There is therefore a need to explore more effective schedules. The study arm will receive MRI simulation-guided boost in short-course preoperative radiotherapy followed by consolidation chemotherapy , which may enhance the shrinkage of tumor comparing with the concurrent chemoradiation.