Abstract
Carbohydrate antigen 19-9 (CA19-9) is one of the most widely used tumor markers in gastrointestinal cancer. However, serum CA19-9 is not a recommended routine measurement in colon cancer. In this study, we evaluated the value of the preoperative serum CA19-9 level for the prediction of postoperative prognosis in stage III colon cancer. The medical records of 367 consecutive patients with stage III colon cancer who underwent curative resection followed by adjuvant chemotherapy with oxaliplatin and capecitabine between December 2007 and April 2015 were retrospectively reviewed. We determined the optimal cutoff value of CA19-9 for 3-year recurrence using the receiver operating characteristic (ROC) method. Differences in disease-free survival (DFS) and overall survival (OS) rates stratified by CA19-9 level were compared by using Kaplan-Meier and log-rank tests. A Cox proportional hazards model was used to identify prognostic variables for DFS and OS. The statistically determined best cutoff value for CA19-9 was 24 U/ml. High CA19-9 levels (> 24 U/ml) were significantly associated with poorly differentiated tumors, abnormal carcinoembryonic antigen (CEA) levels, and a high cumulative incidence of lung metastasis. Additionally, compared with low CA19-9 levels, high preoperative CA19-9 levels were associated with inferior 3-year DFS and OS rates, especially for high-risk patients (T4Nany or TanyN2). Multivariate analyses revealed that CA19-9 was an independent factor associated with both DFS (hazard ratio [HR], 2.248; 95% confidence interval [CI], 1.393-3.628; P = 0.001) and OS (HR: 2.081; 95% CI: 1.137-3.808; P = 0.017). The results of this study showed that high levels of preoperative serum CA19-9 indicated a worse prognostic outcome for stage III colon cancer patients. An early follow-up protocol to assess lung metastasis and a full course of adjuvant chemotherapy should be used for these patients.