High-risk features are used to direct adjuvant therapy for stage II colon cancer. Currently, high-risk features are identified postoperatively, limiting preoperative risk stratification. We hypothesized carcinoembryonic antigen (CEA) can improve preoperative risk stratification for stage II colon cancer. The National Cancer Database (NCDB 2004-2009) was reviewed for stage II colon adenocarcinoma patients undergoing curative intent resection. A novel risk stratification including both traditional high-risk features (T4 lesion, <12 lymph nodes sampled, and poor differentiation) and elevated CEA was developed. Unadjusted Kaplan-Meier and adjusted Cox proportional hazards analyzed overall survival. Concordance Probability Estimates (CPE) assessed discrimination. Seventy-four thousand nine hundred forty-five patients were identified; 40,844 (54.5%) had CEA levels reported and were included. Chemotherapy administration was similar between normal and elevated CEA groups (23.8 vs. 25.1%, p = 0.003). Compared to patients with CEA elevation, 5-year overall survival in patients with normal CEA was improved (74.5 vs. 63.4%, p < 0.001). Restratification incorporating CEA resulted in reclassification of 6912 patients (16.9%) from average to high risk. CPE increased for novel risk stratification (0.634 vs. 0.612, SE = 0.005). The routinely available CEA test improved risk stratification for stage II colon cancer. CEA not only may improve staging of colon cancer but may also help guide additional therapy.
Keywords: CEA; Colon cancer; Risk stratification; Staging.