MRD-Guided Surveillance in Locally Advanced Mid-Low Rectal Cancer (SURVEILLANCE-III)

This study aims to explore the relationship between minimal residual disease (MRD) status and disease recurrence in patients with locally advanced mid-low rectal cancer. MRD refers to the presence of cancer cells that remain in the body after treatment but are undetectable by traditional imaging methods. The study will use a blood-based circulating tumor DNA (ctDNA) methylation test to assess its ability to predict cancer recurrence and survival outcomes. Patients who are newly diagnosed with cT3/N+, M0 mid-low rectal cancer (tumor ≤10 cm from the anal verge) and are eligible for curative-intent treatment will be enrolled. Blood samples will be collected at multiple time points, including before neoadjuvant therapy, before surgery, after surgery, and during follow-up visits over three years. The study will compare MRD status with disease-free survival (DFS), recurrence-free survival (RFS), overall survival (OS), and the time it takes for MRD to detect recurrence compared to standard imaging methods. The goal is to determine whether MRD monitoring can provide an early warning of cancer recurrence and help guide treatment decisions. This study may offer valuable insights into improving postoperative surveillance and personalized treatment strategies for rectal cancer patients.