Assessment of the value of carcinoembryonic antigen reduction ratio as a prognosis factor in rectal cancer.

Background: Carcinoembryonic antigen (CEA) is the most widely used tumor marker for colorectal cancer. This study aimed to investigate the role of CEA reduction ratio after preoperative chemoradiotherapy (CRT).

Methods: We enrolled 284 patients who underwent preoperative CRT followed by radical surgical resection. Patients were divided into 3 groups: serum CEA levels before CRT (pre-CRT CEA) less than 5 ng/mL (group 1); pre-CRT CEA of 5 ng/mL or more with CEA reduction ratio of 50% or more (group 2); and pre-CRT CEA of 5 ng/mL or more with CEA reduction ratio less than 50% (group 3).

Results: The 5-year disease-free survival (DFS) rate was not different between groups 1 (71.8%) and 2 (69.4%) but was significantly lower in group 3 (49.5%). CEA group, lymph node status after CRT (ypN) stage, and histologic type were independent prognostic factors for DFS on multivariate analysis.

Conclusions: CEA reduction ratio might be an independent prognostic factor for DFS in rectal cancer patients treated with preoperative CRT and radical surgery.