Dose Escalated Radiotherapy for Rectal Cancers Using MR-guided Radiotherapy

All patients will receive 45Gy in 25# to mesorectum and elective nodal volumes, and 52.5Gy in 25# as standard to primary gross tumour volume which includes primary tumour, visible nodal disease and extramural vascular invasion if present. Boost dose escalation to a maximum of 60Gy will be delivered to patients with ongoing visible disease from week 2 of treatment onwards.