This is also the staging of pancreatic cancer, which is actually a very specialized issue. Currently, our country mainly adopts the American AJCC staging, which includes both TNM staging and clinical staging, and the TNM staging is a bit more complicated to introduce, for example, whether the tumor has T0 or TX, but of course it is found to have a tumor, mainly because the tumor invasion is very small, even in situ, which we call tumor in situ. When the tumor is less than or equal to two centimeters, we call it T1; when it is greater than two centimeters, we call it T2; when it exceeds the scope of the pancreas itself and invades the periphery of the pancreas, we call it T3; if the tumor grows further, it invades the mesenteric artery or vein, which are two important vessels under the neck of the pancreas, and if there is arterial invasion of these two vessels, we call it T4. What does this T refer to? It refers to the size of the tumor, it means Tumor. The other one is N. What is N? N refers to lymph nodes, when there is lymph node metastasis, we call it N1; if there is no lymph node metastasis, we call it N0. Another one is M. What is M, refers to metastasis, there is metastasis called M1, no metastasis called M0. Stage Ia refers to tumor less than or equal to two centimeters; stage Ib is tumor greater than two centimeters. Stage II also includes stage IIa and stage IIb. Stage IIa mainly refers to tumor invasion to the periphery of the pancreas, while stage IIb, regardless of whether it is called T1, T2, or T3, means that the tumor invades the periphery of the pancreas by more than two centimeters. As long as there is lymph node metastasis, we call it T3, which is the stage III of the tumor. Stage IV tumor is when the tumor has distant metastasis.