Approximately half of patients diagnosed with rectal cancer are offered chemotherapy and radiotherapy treatment (CRT) before surgery. There is great variability in how each tumour responds to CRT. Approximately 30% of tumours completely respond and no cancer cells can be found in the cancer specimen removed at surgery. Other tumours do not respond at all or occasionally continue to grow during treatment.~In many hospitals patients receive an MRI scan before and after CRT treatment. Emerging evidence suggests that by viewing the MRI scans in a smarter way by assessing 'mrTRG' (MR Tumour Regression Grade) it is possible to assess how the tumour has responded to treatment. The TRIGGER Trial aims to evaluate mrTRG as a tool for stratifying patients according to their response to treatment.~Patients will be randomised (1:2 ratio) to a control and intervention arm. Patients in the control arm will receive best current practice of surgery at 6-8 weeks after CRT and then a standard course of chemotherapy. Patients in the intervention arm will receive a treatment plan according to their response to CRT, assessed using the mrTRG. Patients who have a good response to CRT will defer surgery until the cancer stops reducing in size or avoid surgery altogether if the cancer cannot be detected with repeat scans and assessments. Patients who have a poor response to CRT will have additional pre-operative chemotherapy. The investigators will be able to see if this reduces the size of the tumour further, before a decision is made about proceeding to surgery, and if this lowers the risk of the tumour spreading.
This trial evaluates a novel imaging method called magnetic resonance tumour regression grade (mrTRG) to assess how well a tumour has responded to chemoradiotherapy in patients with rectal cancer. The TRIGGER Trial aims to evaluate mrTRG as a tool for stratifying the management of patients according to their response to treatment.