Using ctDNA Methylation to Monitor Metastatic Colorectal Cancer Treatment (PROMET)

This study will enroll patients with histologically confirmed, recurrent or metastatic colorectal cancer who are eligible to receive radiotherapy in combination with standard-of-care chemotherapy, with or without PD-1 inhibitors. The study will employ ctDNA methylation detection technology to quantitatively assess ctDNA methylation levels in patient plasma samples. Blood samples will be collected at baseline and at multiple predefined timepoints during treatment. In addition, participants will undergo standard imaging surveillance (CT/MRI) every three months. The study aims to correlate ctDNA dynamics with therapeutic response, time to recurrence, and survival outcomes. Ultimately, it seeks to evaluate the potential of ctDNA monitoring for predicting treatment efficacy and prognosis, and to explore its utility in guiding clinical management for metastatic colorectal cancer.