The clinicopathological data of patients diagnosed with primary gastric adenocarcinoma in Qinghai University Affiliated Hospital from January 2012 to December 2016 and treated with radical surgery (training set) were used for retrospective analysis. The inclusion criteria of the patients were as follows: (1) histopathology was consistent with gastric adenocarcinoma; (2) anti-inflammatory drugs were not used within 1 week before the operation; (3) no trauma, renal failure, and/or liver failure and infectious diseases; and (4) serum CEA and blood routine test were performed within 1 week before the operation. The exclusion criteria were as follows: (1) T4b (tumor invades adjacent structures/organs could not be resected by R0); (2) peritoneal spread or distant organ metastasis was confirmed during or after the operation; (3) neoadjuvant chemotherapy before the operation; and (4) incomplete clinicopathological data. Additional external validation was performed using a dataset from Fujian Medical University Union Hospital between January 2012 to December 2013, which satisfied the aforementioned inclusion and exclusion criteria. Finally, a total of 803 cases in the training set and 794 cases in the validation set were included in this study. According to Japan's 14th edition of the regulations for the treatment of GC, the scope of gastrectomy was selected, and the lymph nodes around the stomach were cleaned ⁸. TNM staging was carried out according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging standard published in 2016 ⁹.