Gastric adenocarcinoma is commonly used in TNM staging method, and the pathological basis of staging is mainly the depth of tumor infiltration, lymph nodes and distant metastasis. According to different combinations of TNM, gastric cancer can be divided into I-IV clinicopathological stages, with I stage being early stage and IV stage being late stage. T represents the depth of primary tumor infiltration of the gastric wall. T1: tumor invades the lamina propria, the muscular layer of the mucosa or the submucosal layer; T2: tumor infiltrates the lamina propria; T3: tumor penetrates the subplasma connective tissue without invading the visceral peritoneum or neighboring structures; T4a: tumor invades the plasma membrane; T4b: tumor invades neighboring tissues or organs. N represents local lymph node metastasis. n0: no lymph node metastasis; n1: 1 to 2 regional lymph node metastasis; n2: 3 to 6 regional lymph node metastasis; n3: more than 7 regional lymph node metastasis. M, on the other hand, represents the situation of distant metastasis of the tumor. m0: without distant metastasis; m1: with distant metastasis. Stage I, including T1~2N0MO, T1N1MO. Stage IV, including T any staging N any staging M1. Early gastric adenocarcinoma can be treated by surgical resection, and at the same time, radiotherapy can be assisted to improve the prognosis and even cure the disease. Advanced gastric adenocarcinoma is difficult to treat the disease by surgery, and the prognosis is poorer, so it can be treated by radiotherapy or targeted therapy to relieve the symptoms, control the tumor progression, improve the quality of life and prolong the survival time. Therefore, after discovering gastric adenocarcinoma, it is recommended to have standardized treatment under doctor’s guidance as soon as possible to improve the survival rate.