The staging system of gastric cancer mainly comes from three major organizations: the Joint Commission on Cancer of the United States, the Japanese Society for the Study of Gastric Cancer and the International Anti-Cancer Committee, which produced a unified international TNM staging standard system for gastric cancer for the first time after numerous agreements in 1992.
It refers to the depth of primary tumor infiltration into the gastric wall (in order to facilitate the estimation of the extent and size of the tumor, the stomach is divided into three zones: upper, middle and lower, i.e. three equal points are drawn in the whole length of the major and minor curves of the stomach, linking the corresponding points of the major and minor curves, the upper 1/3 zone includes the cardia and fundus, the middle 1/3 zone is the bulk of the stomach body, and the lower 1/3 zone includes the gastric sinus).
T1: Regardless of the size of the tumor, the lesion is only confined to the mucosa or submucosa layer of early gastric cancer.
T2: The tumor invades the muscular layer of the stomach wall, but the size does not exceed 1/2 of one partition.
T3: The tumor invaded the plasma layer of the gastric wall, or did not invade the plasma layer, but the lesion was larger than 1/2 of one partition, but not beyond one partition.
T4: The tumor occupies more than one partition (T4a) or has involved the surrounding organs (T4b).
Refers to lymph node metastasis
N0: No lymph node metastasis.
N1: There is metastasis in the lymph nodes of station 1 closest to the cancer focus and close to the stomach wall.
It includes the right and left cardia, gastric lesser curvature, gastric greater curvature, suprapyloric and subpyloric as well as splenic hilar lymph nodes.
N2: There is metastasis in the lymph nodes of station 1 in the distant part of the cancer site (such as metastasis in the paracranial or splenic gate lymph nodes in sinus cancer or metastasis in the upper and lower pylorus lymph nodes in cardia cancer).
Or there is metastasis in the lymph nodes of the left paragastric artery, common hepatic artery trunk, splenic artery trunk and post-pancreaticoduodenal station 2.
N3: There were metastasis of station 3 lymph nodes around the paracavalicular artery, parietal aorta, hepatoduodenal ligament, mesenteric root and middle colonic artery.
Refers to distant metastases, including left supraclavicular lymph node metastasis, hematogenous metastasis and abdominal implantation.
M0: No distant metastasis.
M1: with distant metastasis.
Staging
Stage I: refers to superficial gastric cancer without lymph node metastasis, or tumor has invaded the muscular layer but not more than 1/2 of one partition;
Stage II: refers to superficial carcinoma with lymph node metastasis in the first station, T2 and T3 carcinoma, and T3 carcinoma without lymph node metastasis also belongs to this stage;
Stage III: Tumors of various sizes with lymph node metastasis from the second station, or tumors with lymph node metastasis from the first station or even without lymph node metastasis that have exceeded one partition;
Stage IV: Any tumor with third station lymph node metastasis or distant metastasis, regardless of the size of the tumor, belongs to this stage.
If the primary tumor is confined to the mucosal layer and has not invaded the intrinsic layer of mucosa, it is considered as carcinoma in situ, which is indicated by Tis, when the tumor is TisN0M0, it is considered as carcinoma in situ, also called stage 0. Due to the advancement of diagnostic technology, it is possible to make preoperative judgments on tumor infiltration and metastasis and perform clinical staging, which is expressed as CTNM.