BACKGROUND: This clinicopathological study evaluated the utility of serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 as predictors of locoregional recurrence and long-term disease-free survival in patients with gastric cancer.METHODS: During the period January 1989 to December 1994, 485 patients with primary gastric cancer were evaluated. Gastrectomies were performed in 434 patients. Prognostic factors were analyzed by the Kaplan-Meier method and multivariate analysis, using Cox regression.RESULTS: Elevated serum CEA and CA19-9 levels were observed in 92 of the 485 patients (19.0%), and in 95 of the 435 patients (21.8%), respectively, and both markers were elevated in 29 of these 435 patients (6.7%). Elevated serum CEA and CA19-9 levels correlated well with lymph node metastasis, lymphatic invasion, vessel invasion, stage grouping, depth of invasion, and curability. Patients with elevated serum CEA levels were at significantly higher risk of having all recurrence factors than were those with normal serum CEA levels. Patients with elevated serum CA19-9 levels were at significantly higher risk of having peritoneal metastases and distant metastases than were those with normal serum CA19-9 levels. A significant difference in the cumulative survival curves of patients was demonstrated between those with elevated and those with normal serum CEA or CA19-9 levels, even for patients at the same disease stage (stage III). Patients with elevated levels of both markers had a significantly worse prognosis than patients in whom the levels of both markers were normal. In patients who underwent gastrectomy, elevated serum CEA levels either preoperatively or within 3 weeks after gastrectomy were associated with significantly worse prognosis than were normal levels. When the cutoff level of serum CEA was increased to 10 ng/ml, serum CEA, age, lymph node metastasis, and surgical stage grouping were selected as independent prognostic factors by multivariate analysis of 14 prognostic factors, using Cox regression.CONCLUSION: Serum CEA and CA19-9 levels provide additional prognostic information in patients with primary gastric cancer. In particular, an elevated serum CEA level provides additional prognostic information and is a useful indicator of curability in patients who undergo gastrectomy. Serum CEA level is an independent prognostic factor in patients with primary gastric cancer.