A Prospective Feasibility Study Using ctDNA to Tailor Neoadjuvant Chemotherapy for Patients With Colorectal or Appendiceal Adenocarcinoma

This study is investigating whether a blood test that detects tumor DNA (called ctDNA) can help doctors personalize chemotherapy decisions for patients with colorectal or appendix cancer that has spread to the lining of the abdomen (peritoneal metastases). The goal is to see if tailoring treatment based on this test improves outcomes. **You may be eligible if...** - You are 18 or older with a confirmed diagnosis of colorectal or appendiceal cancer that has spread to the abdomen's lining - Your cancer is potentially removable by surgery - Your overall health (ECOG 0–1) allows for chemotherapy - You have adequate blood counts, liver, and kidney function **You may NOT be eligible if...** - Your cancer has also spread to the brain, liver, or lungs - You have had serious complications from prior chemotherapy - You have uncontrolled medical or psychiatric conditions - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.