Carcinoembryonic Antigen as a Predictor of Pathologic Response and a Prognostic Factor in Locally Advanced Rectal Cancer Patients Treated With Preoperative Chemoradiotherapy and Surgery

Abstract

To evaluate the role of serum carcinoembryonic antigen (CEA) as a predictor of response to preoperative chemoradiotherapy (CRT) and prognostic factor for rectal cancer. The study retrospectively evaluated 352 locally advanced rectal cancer patients who underwent preoperative CRT followed by surgery. Serum CEA levels were determined before CRT administration (pre-CRT CEA) and before surgery (post-CRT CEA). Correlations between pre-CRT CEA levels and rates of good response (Tumor regression grade 3/4) were explored. Patients were categorized into three CEA groups according to their pre-/post-CRT CEA levels (ng/mL) (Group A: pre-CRT CEA <or= 3; B: pre-CRT CEA >3, post-CRT CEA <or=3; C: pre- and post-CRT CEA >3 ng/mL), and their oncologic outcomes were compared. Of 352 patients, good responses were achieved in 94 patients (26.7%). The rates of good response decreased significantly as the pre-CRT CEA levels became more elevated (CEA [ng/mL]: <or=3, 36.4%; 3-6, 23.6%; 6-9, 15.6%; >9, 7.8%; p < 0.001). The rates of good response were significantly higher in Group A than in Groups B and C (36.4% vs. 17.3% and 14.3%, respectively; p < 0.001). The 3-year disease-free survival rate was significantly better in Groups A and B than in Group C (82% and 79% vs. 57%, respectively; p = 0.005); the CEA grouping was identified as an independent prognostic factor (p = 0.025). In locally advanced rectal cancer patients, CEA levels could be of clinical value as a predictor of response to preoperative CRT and as an independent prognostic factor after preoperative CRT and curative surgery.