Using MRI Tumour Regression Grade to Guide Treatment in Locally Advanced Rectal Cancer A UK Phase III Trial Offering Surgery Avoidance or Treatment Intensification Based on Response

What this Trial Is About

Researchers are studying the use of magnetic resonance tumour regression grade mrTRG as a new imaging biomarker to guide treatment decisions for patients with locally advanced rectal cancer. This phase III trial is unique in the UK as it offers a watch and wait approach for patients showing a good response to preoperative treatment, potentially avoiding surgery. The trial aims to validate mrTRGs ability to identify patients who can safely defer surgery and those who may need intensified treatment, thus tailoring care based on MRI findings. Participants are randomly assigned to one of two groups. The control group receives management according to national guidelines with post-treatment MRI scans interpreted without mrTRG assessment. The intervention group has their post-treatment MRI scans evaluated by specially trained radiologists to assign an mrTRG grade. Patients with a good response mrTRG 1 & 2 are offered a watch and wait approach to avoid surgery, while those with a poor response mrTRG 3-5 have their cases reviewed by a local colorectal multidisciplinary team for further treatment planning and surveillance. Treatment decisions, including chemotherapy use, follow routine clinical practice and are documented but not dictated by the trial. Participants undergo regular monitoring for up to five years, including routine post-treatment MRI scans following the MERCURY protocol and quality of life questionnaires at registration, 3 years, and 5 years. The study assesses if surgery can be safely avoided after a good MRI response and tracks surgical outcomes, survival, quality of life, and economic impact. Additional evaluations include reproducibility of mrTRG readings, molecular and immunological markers, and circulating tumor DNA to predict relapse. This long-term follow-up aims to improve personalized treatment for rectal cancer patients.

Magnetic Resonance Tumour Regression Grade (mrTRG) as a Novel Biomarker - Phase III Non CTIMP Trial