Background: Carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are the most common tumor markers for colorectal cancer. The aim of this study was to evaluate the possibility of adding them into the current staging system by analyzing their prognostic significance.
Materials and methods: The study population was patients (n = 574, 67.1 +/- 11.3 years old, 397 males) who received potentially curative resection of colorectal adenocarcinoma (stage I-III) between January 1994 and August 2002, including preoperative measurements of CEA and CA19-9. Clinicopathological characteristics and associated follow-up data were retrospectively collected by reviewing available medical charts. CEA higher or equal to 5 ng/ml was defined as abnormal (CEA+). The CA19-9 level was set at 37 U/ml (CA19-9+). Patients were further divided into four groups (1, 2, 3, 4) according to the results of these two markers (CEA/CA19-9: -/-, -/+, +/-, and +/+). Survival was analyzed for AJCC staging, CEA (+) versus (-), CA19-9 (+) versus (-), and four groups.
Results: CEA and CA19-9 survival curves were not significantly different. However, the combined use of the two markers revealed a significant survival benefit (P = 0.035) of group 1 ("-" for both markers) over 4 ("+" for both) in stage II.
Conclusions: Patients with an elevated level of both CEA and CA19-9 in stage II of colorectal cancer have a significantly poorer prognosis than those with normal levels of these markers. We recommend adding both CEA and CA19-9 to the current staging system.