[Development trend of assessment system in gastric cancer based on evolution of staging criteria]

There are two major stage classification systems for gastric cancer: the tumor-node-metastasis (TNM) staging by the International Union against Cancer (UICC)/the American Joint Committee on Cancer(AJCC) and the Japanese Classification of Gastric Carcinoma by the Japanese Gastric Cancer Association(JGCA). The evolution of these two systems showed the advancement of gastric cancer treatment. The independence of TNM and JGCA staging system is not conducive to global communication and cooperation. The integration of 2010 Japan's 14th edition of the General Rules for Gastric Cancer Study and the 7th edition of UICC/AJCC TNM staging formed an internationally unified clinical staging system. TNM staging determined by the N factor according to the number of lymph node metastasis more accurately stratified the survival curves of different stages. On January 1, 2018, the 8th edition of the TNM staging system for gastric cancer was officially implemented. The 8th edition of TNM staging provided a new definition of the staging criteria for esophagogastric junction cancer. On the basis of a single staging system, clinical TNM staging(cTNM) and neoadjuvant treatment staging (ypTNM) were added. N3a and N3b were seperately staged, and adjustments were made to the histological grading. A comprehensive treatment plan was determined by accurate clinical staging in the model of multidisciplinary diagnosis and treatment for gastric cancer. Comprehensive application of endoscopic ultrasonography (EUS), multi-slice spiral CT(MDCT), positron computed tomography combined with CT(PET-CT), and staging laparoscopy can improve the accuracy of preoperative staging of gastric cancer. The emergence of ypTNM staging is a highlight of the 8th edition of the staging, but due to insufficient case data for cTNM and ypTNM staging, the staging criteria are relatively broad, and more data validation, refinement and revision are required in the future. The 8th edition system is superior to the 7th edition system in terms of homogeneity, discriminatory ability, and monotonicity of gradients for Chinese patients with gastric cancer. The new version of the staging can guide clinicians to develop treatment plans more rationally, evaluate the treatment more scientifically, and assess the prognosis more accurately. New lymph node staging methods such as metastatic rate(rN), log odds of positive lymph nodes (LODDS), and a new staging system based on the anatomical range of lymph node metastasis can also better predict the prognosis of patients. At present, molecular type of gastric cancer has little significance for prognosis guidance, and may be rewritten or supplemented with TNM staging of gastric cancer in the future. This article discusses the history, current status and research progress of gastric cancer staging.