Purpose: We retrospectively analyzed preoperative levels of carbohydrate antigen (CA) 19-9 in colorectal cancer (CRC) patients to determine the prognostic value of CA19-9 in CRC patients with normal carcinoembryonic antigen (CEA) levels.
Methods: A total of 639 patients who underwent curative surgery at Taipei Veterans General Hospital between 2002 and 2006 were enrolled. We excluded 254 patients (39.7 %) with high preoperative CEA levels and analyzed 385 patients with normal CEA levels. The measured endpoint was the postoperative disease-free survival (DFS). The prognostic value of CA19-9 was determined using log-rank test and Cox regression analysis.
Results: High CA19-9 levels were significantly associated with advanced disease and were detected in 5.8 % of patients with stage I disease, 11.7 % of those with stage II disease, and 22.5 % of those with stage III disease (P < 0.001). The 5-year DFS in patients with normal CA19-9 levels was 82.0 %, which was significantly higher than that in patients with high CA19-9 levels (68 %; P < 0.001). In a multivariate analysis, the most important independent factor affecting the 5-year DFS was tumor-node-metastasis stage (95 % CI, 1.26-2.36; HR = 1.72). After stratification by other factors, high CA19-9 level remained an independent prognostic factor for patients with normal CEA levels. Patients with high CA19-9 levels also showed a higher incidence of lung metastasis (23.1 %) than those with normal CA19-9 levels (7.2 %).
Conclusions: CA19-9 may be a prognostic factor for CRC patients with normal CEA levels. An aggressive follow-up protocol for lung metastasis should be used for these patients.