CtDNA-guided Selection of Adjuvant Chemotherapy Regimens for Elderly Colon Cancer Patients After Surgery: a Single-center, Randomized, Controlled Study

6 months of adjuvant chemotherapy with 5-FU monotherapy. The follow-up strategy for the four groups of subjects will be the same, including but not limited to chest plain or enhanced CT, abdominal/pelvic enhanced CT, and detection of the tumor marker carcinoembryonic antigen (CEA), until disease progression occurs. All patients will undergo peripheral blood ctDNA-MRD testing again six months after surgery.

XELOX intensive treatment group. The follow-up strategy for the four groups of subjects will be the same, including but not limited to chest plain or enhanced CT, abdominal/pelvic enhanced CT, and detection of the tumor marker carcinoembryonic antigen (CEA), until disease progression occurs. All patients will undergo peripheral blood ctDNA-MRD testing again six months after surgery.