Changing patterns of Serum CEA and CA199 for Evaluating the Response to First-line Chemotherapy in Patients with Advanced Gastric Adenocarcinoma

Background: This study was designed to investigate the value of CEA and CA199 in predicting the treatment response to palliative chemotherapy for advanced gastric cancer. Materials and Methods: We studied 189 patients with advanced gastric cancer who received first-line chemotherapy, measured the serum CEA and CA199 levels, used RECIST1.1 as the gold standard and analyzed the value of CEA and CA199 levels changes in predicting the treatment efficacy of chemotherapy. Results: Among the 189 patients, 80 and 94 cases had increases of baseline CEA (${\geq}5ng/ml$) and CA199 levels (${\geq}27U/ml$), respectively. After two cycles of chemotherapy, 42.9% patients showed partial remission, 33.3% stable disease, and 23.8% progressive disease. The area under the ROC curve (AUC) for CEA and CA199 reduction in predicting effective chemotherapy were 0.828 (95%CI 0.740-0.916) and 0.897 (95%CI 0.832-0.961). The AUCs for CEA and CA199 increase in predicting progression after chemotherapy were 0.923 (95%CI 0.865-0.980) and 0.896 (95%CI 0.834-0.959), respectively. Patients who exhibited a CEA decline ${\geq}24%$ and a CA199 decline ${\geq}29%$ had significantly longer PFS (log rank p=0.001, p<0.001). With the exception of patients who presented with abnormal levels after chemotherapy, changes of CEA and CA199 levels had limited value for evaluating the chemotherapy efficacy in patients with normal baseline tumor markers. Conclusions: Changes in serum CEA and CA199 levels can accurately predict the efficacy of first-line chemotherapy in advanced gastric cancer. Patients with levels decreasing beyond the optimal critical values after chemotherapy have longer PFS.