Controversies exist regarding the survival benefits of intensive follow‐up after curative resection of colorectal cancer.20, 21, 22, 23 In rectal cancer alone, several studies have shown that intensive monitoring is beneficial in terms of detecting treatable residual disease such as local recurrence.22, 24, 25 The results of the present study suggest that patients with rectal cancer showing elevated preoperative CEA may require different surveillance from patients with normal preoperative CEA. Here, CEACAM5 is linked to colorectal cancer.