cfDNA 5mC/5hmC Biomarkers to Predict Chemotherapy Response in Metastatic Colorectal Cancer

This study is analyzing stored blood samples from people with metastatic colorectal cancer (colorectal cancer that has spread) to see whether specific chemical modifications on tumor DNA released into the bloodstream (called 5mC and 5hmC markers) can predict how well a patient will respond to standard chemotherapy regimens like FOLFOX or FOLFIRI. **You may be eligible if...** - You have been confirmed to have metastatic colorectal adenocarcinoma - You received first-line chemotherapy with FOLFOX or FOLFIRI - Blood (serum or plasma) samples collected before treatment started are available - Your tumor's RAS and BRAF mutation status is documented - Your response to treatment was formally assessed using standard imaging criteria **You may NOT be eligible if...** - Your stored blood samples are of insufficient quality or quantity - Your cancer was not an adenocarcinoma (a different cancer cell type) - You had another concurrent cancer requiring systemic treatment - You have an active autoimmune or inflammatory disease that could affect the DNA markers being studied Talk to your doctor to see if this trial is right for you.