Variable collection
tumor, death, adenocarcinoma, N0, Cancer
TUMOR, SIGNET RING CELL CARCINOMA, ADENOCARCINOMA, CANCER
According to the instructions provided by the National Cancer Institute, the code data extracted from the SEER database was translated. The external validation cohort data was obtained through the hospital medical record system. The variables collected in this study were mainly divided into three categories: patient‐related variables, disease‐related variables, and follow‐up information. (1) Patient‐related variables: race, sex, age at diagnosis, and marital status. (2) Disease‐related variables: histological type, differentiation grade, 7th edition AJCC clinical stage (TNM), tumor size, examined lymph nodes (ELN), positive lymph nodes (PLN), and LODDS, which is calculated as LODDS = log[(PLN + 0.5)/(ELN‐PLN + 0.5)]. (3) Follow‐up information: survival status, cause of death, and survival time.Each variable was categorized as follows: marital status, unmarried or married; sex, male or female; histological type, adenocarcinoma or signet ring cell carcinoma; differentiation grade, G1–2 (well to moderately differentiated) or G3–4 (poorly differentiated and undifferentiated); and the 7th edition AJCC clinical stage, which divided T stage into T1, T2, T3, and T4 and N stage into N0, N1, N2, and N3. The X‐tile software was used to determine the optimal cutoff values for the three continuous variables of age, tumor size, and LODDS. Age was classified as <65, 65–71, and >71 years; tumor size was classified as <2.6, 2.6–4.8, and <4.8 cm; LODDS was classified as LODDS1 (< −1.20), LODDS2 (−1.20 to −0.60), and LODDS3 (< −0.60).