Background: The aim of this longitudinal study was to try and improve the specificity of carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 in monitoring tumor recurrence in patients with resectable gastric adenocarcinoma by setting suitable elevation levels.
Methods: One hundred eighty-one patients with resectable gastric adenocarcinoma were considered. Serum samples were obtained preoperatively and every 3 months postoperatively.
Results: Preoperative CEA and CA19-9 positivity rates were 19.9% and 18.2%. The specificity and sensitivity of CEA elevation to monitor recurrence were 92.9% and 23.4% versus 76.5% and 78.9% in CEA-negative versus CEA-positive patients, respectively. For CA19-9 the specificity and sensitivity were 95.0% and 18.8% versus 60.0% and 83.3% in CA19-9-negative versus CA19-9-positive patients, respectively. When we set the elevation level of CEA at 5 ng/mL, the specificity of CEA elevation to monitor recurrence increased to 94.1% for CEA-positive patients. The specificity increased to 93.3% for CA19-9-positive patients when the CA19-9 elevation level was set at 100 U/mL.
Conclusions: For CEA- or CA19-9-positive patients with resectable gastric adenocarcinoma we can increase the specificity of CEA and CA19-9 by setting the elevation level of CEA at 5 ng/mL and CA19-9 at 100 U/mL.