Dynamic Monitoring of ctDNA Methylation to Predict Relapse in Colorectal Cancer After Radical Resection (POSTCA)

At present, the main treatment of colorectal cancer (CRC) is surgical resection. CRC patients after radical surgery have good overall survival. However, there are still a large number of patients with postoperative recurrence. The postoperative recurrence rate of stage II CRC patients is 20-30%, and that of stage III CRC patients is 50-60%. Currently, there is no effective measures to predict whether patients suffer postoperative relapse. Patients can only periodically visit doctors in the hope of timely treatment in case of recurrence. Current clinical monitoring methods mainly include imaging detection and tumor markers detection. However, long-term monitoring may affect patients' quality of life and increase patients' economic burden. Therefore, biomarkers that can predict the prognosis of patients and screen out those who need intensive follow up are urgently warranted. At present, imaging is the mainly used approach to monitor tumor recurrence. Quantitative determination of ctDNA methylation in plasma may find tumor recurrence trend before imaging detection, indicating that quantitative determination of ctDNA methylation in plasma is a more sensitive monitoring approach than traditional imaging detection. Can plasma ctDNA methylation be a new recurrence monitoring technique and prognostic prediction method of CRC in clinical practice? In this study, we aimed to monitor the dynamic level of plasma ctDNA methylation after surgery in CRC patients, and to explore the advantages of plasma ctDNA methylation detection over traditional CRC in recurrence monitoring and prognosis prediction. This is a prospective, multicenter, observational, single-blinded controlled study. Dynamic monitoring of CRC patients was performed using the previously established colorectal tumor-specific plasma ctDNA methylation markers. Dynamic monitoring of plasma ctDNA methylation before and after treatment and at regular follow-up in patients with CRC after radical resection of tumor, to explore the predictive effect of postoperative plasma ctDNA methylation on postoperative recurrence and whether dynamic monitoring of postoperative ctDNA methylation could be earlier than imaging examination to indicate tumor recurrence.