Perioperative carcinoembryonic antigen (CEA) is a key marker for predicting survival and guiding treatment in stage II and III colorectal cancer.

• Elevated perioperative CEA is linked to worse overall survival (OS) and disease-free survival (DFS).
• Patients not receiving adjuvant chemotherapy with high CEA experienced significantly poorer outcomes; adjuvant therapy notably improved OS.

Surgeons should consider perioperative CEA levels in decision-making to personalize treatment strategies, especially for those at higher risk of recurrence.

• The two-year post-surgery period is critical for monitoring recurrence in patients with elevated CEA.