Gastric adenocarcinomas are staged using the American Joint Committee on Cancer’s 8th TNM classification. The perigastric ligaments, mesentery, omentum, and potential spaces between the parietal and visceral peritoneal linings play are important structures for staging. Stage IIIA (T4a, N2, M0): The tumor has grown from the stomach wall into the serosa, and has spread to 3 to 6 lymph nodes, but has not spread to distant parts of the body. The American Joint Committee on Cancer (AJCC) tumor/node/metastasis (TNM) classification and staging systems for gastric cancer are provided below. [1] Post-neoadjuvant treatment staging. Tumor that involves the gastrocolic or gastrohepatic ligaments or penetrates into the greater or lesser omentum without perforating the visceral peritoneum covering these structures is coded T2. Any perforation of the visceral peritoneum covering the gastric ligaments or omentum is classified T3. Gastric carcinoma is staged using the American Joint Committee on Cancer (AJCC) 8th edition TNM classification system, which categorizes disease based on tumor depth (T), lymph node involvement (N), and distant metastasis (M). 1 There are 4 main stages of tumour size in stomach cancer. T1 means the tumour has started to grow into the wall of the stomach. It’s divided into T1a and T1b: T2 means the tumour has grown into the muscle layer of the stomach. T3 means the tumour has grown into the outer lining of the stomach. The main tumor is growing into the subserosa layer (T3), AND the cancer has spread to 3 to 6 nearby lymph nodes (N2). The cancer has not spread to distant parts of the body (M0).