Clinicopathological variables
tumor, T stage, cardia, AJCC
TUMOR
The following characteristics were extracted from the SEER database: year of diagnosis, gender, age, race, marital status, grade, AJCC stage, T stage, N stage, M stage, primary site, tumor size, regional nodes examined (RNE), surgery, radiation therapy, chemotherapy, survival time and vital status. Patients were categorized according to the primary site (cardia, distal site, middle site, and overlapping/NOS), tumor size (≤ 2 cm, ≤5 cm, and >5 cm), and RNE (0, 1–15, and ≥ 16). The GNEC patients were converted to the 8th edition of the AJCC TNM staging system based on the 7th edition in the SEER database. In the research, CSS was regarded as the endpoint. It was defined as the period from diagnosis to cancer-related mortality.