In this phase I single-arm clinical study, 20 patients with T4 unresectable locally advanced colon cancer are proposed to be enrolled, who will be treated with MR-Linac with short course radiotherapy (25Gy/5F), followed by 4 cycles of mFOLFOX6 or 3 cycles of XELOX chemotherapy, then radical surgical resection, and then postoperatively with 8 cycles of mFOLFOX6 or 5 cycles of XELOX. The study will assess patients' surgical R0 resection rate, pCR or cCR rate, PFS, OS, and related adverse effects of treatment, aiming to explore the feasibility, safety, and efficacy of MR-Linac in the treatment of unresectable locally advanced colon cancer.
Patients over 18 years old
Patients can remain in a stationary position on the treatment bed for 1-1.5 hours
ECOG score 0-1
Pathological diagnosis of colon adenocarcinoma, clinical stage cT4N0-2M0
Patients with dMMR or MSI-H
Presence of other types of tumors in addition to colon adenocarcinoma
Claustrophobia or inability to undergo MRI or treatment due to the presence of metal implants or other reasons
Distant metastasis (M1)
Single group
MR-linac
RadiationPatients enrolled will be treated with MR-Linac with short course radiotherapy (25Gy/5F), followed by 4 cycles of mFOLFOX6 or 3 cycles of XELOX chemotherapy, then radical surgical resection, and then postoperatively with 8 cycles of mFOLFOX6 or 5 cycles of XELOX chemotherapy.
MRI-linac Treatment Completion Rate
Is adaptive radiotherapy guided by MRI feasible for patients with locally advanced unresectable colon cancer. The feasibility of each patient will be recorded as a binary variable (1=feasible; 0=not feasible). Completion Rate = Number of Completions / Total ITT Enrollment
Clinical complete response (cCR)
Clinical complete response refers to the absence of detectable tumor clinically after treatment. Number of cCR cases/Number of cases completed for follow-up evaluation
Pathological complete response (pCR)
Pathological complete response is defined as the absence of any signs of cancer in tissue samples after treatment. Number of pCR cases / Number of completed surgeries
Toxicity reaction (CTC 4.0 standard）
CTC 4.0, also known as Common Terminology Criteria for Adverse Events version 4.0, is an extensively used classification system for assessing drug toxicity. This system categorizes drug toxicity into five levels: Grade 0, Grade 1, Grade 2, Grade 3, and Grade 4.
R0 resection rate
During surgery, the R0 resection rate refers to the complete removal of the entire tumor with no residual abnormalities present in the surrounding normal tissue. R0 rate = Number of R0 cases / Total number of surgical procedures performed
Surgical complications
Surgical complications refers to adverse events or problems that arise during or after a surgical procedure. These complications can range from minor issues to serious complications that may have significant consequences for the patient.
Local control rate
Proportion of cases in remission and stable disease after treatment, i.e., proportion of patients who did not experience disease progression.
Online adaptation time, compliance rate, technical success rate
This pilot analysis was pre-specified in the registered protocol as an initial feasibility/run-in phase. Number of successful cases with the initial feasibility/run-in phase.
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