Supplementary Material for: Proposal of the second cutoff of serum carcinoembryonic antigen levels to stratify patients into low, intermediate, and high risks at recurrences after curative resection of gastric cancer|胃癌数据集|复发风险预测数据集

Introduction: Carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are widely used for various cancers, with the cut-off values of 5.0 ng/mL and 37.0 IU/mL, respectively. However, these cutoff values are not for specific diseases or purposes but are uniformly used for any disease and any purpose . It is also unclear as to whether patients are at equal risk of recurrence if they are below the cutoff values. This study aimed to investigate the optimal cutoff of serum tumor markers in the stratification of recurrence risk after curative resection of gastric cancer. Methods: We constructed a nine-center integrated database of patients recieved gastrectomy between January 2010 and December 2014 with a 5-year follow-up period. We determined the cutoff value of preoperative serum tumor marker levels correlated with postoperative recurrences and evaluated its performance in risk stratification for recurrences in 948 patients with pStage II/III gastric cancer who underwent radical resection. Results: The hazard ratio for postoperative recurrences increased at two points of preoperative CEA levels; 3.6 ng/mL and 5.0 ng/mL, which were set as cutoffs. These two cutoffs stratified relapse-free survival into three levels. Conclusions: By adding a second cutoff value for preoperative serum CEA, which was proposed specifically for the prediction of recurrences, patients can be stratified into low-, intermediate-, and high-risk recurrences after curative resection of gastric cancer.