Prognostic Role of Carcinoembryonic Antigen Level after Preoperative Chemoradiotherapy in Patients with Rectal Cancer

Background The prognostic role of post-chemoradiotherapy (CRT) carcinoembryonic antigen (CEA) level is not clear. We evaluated the prognostic significance of post-CRT CEA level in patients with rectal cancer after preoperative CRT. Methods We reviewed 659 consecutive patients who underwent preoperative CRT and total mesorectal excision for non-metastatic rectal cancer. Patients were categorized into two groups according to post-CRT serum CEA level: low CEA (< 5 ng/mL) and high CEA (>= 5 ng/mL). Results Median post-CRT CEA level was 1.7 ng/mL (range, 0.1-207.0). A high post-CRT level was significantly associated with ypStage, ypT category, tumor regression grade, and pre-CRT CEA level. The 5-year overall survival rate of the 659 patients was 87.8% with a median follow-up period of 57.0 months (range, 1.4-176.4). When the post-CRT CEA groups were divided into groups according to pre-CRT CEA level, the 5-year overall survival rates were significantly different (P < 0.001 and P = 0.001, respectively). Post-CRT CEA level was an independent prognostic factor for overall survival. Multivariate analysis revealed that operation method, differentiation, perineural invasion, postoperative chemotherapy, tumor regression grade, and post-CRT CEA level were independent prognostic factors for overall survival. Conclusion The level of serum CEA after preoperative CRT was an independent prognostic factor for overall survival in patients with rectal cancer.