Table 1.
Eighth edition American Joint Committee on Cancer (AJCC) Tumor Nodes Metastasis (TNM) staging for gastric neoplasms with suggested imaging for staging (adapted from Amin et al. [12] and from the National Comprehensive Cancer Network (NCCN) Guidelines [13]).
| 8th AJCC Gastric Cancer TNM Staging | Definition | Imaging |
|---|---|---|
| T | ||
| TX | Primary tumor cannot be assessed | EUS is the modality of choice in assessing the invasion depth of gastric cancer. |
| T0 | No evidence of primary tumor | |
| Tis | Carcinoma in situ: intraepithelial tumor without invasion of the lamina propria | |
| T1 | Tumor invades lamina propria, muscularis mucosae, or submucosa | |
| T1a | Tumor invades lamina propria or muscularis mucosae | |
| T1b | Tumor invades submucosa | |
| T2 | Tumor invades muscularis propria | |
| T3 | Tumor penetrates subserosal connective tissue without invasion of visceral peritoneum or adjacent structures T3 tumors also include those extending into the gastrocolic or gastrohepatic ligaments or into the greater or lesser omentum, without perforation of the visceral peritoneum covering these structures |
|
| T4 | Tumor invades serosa (visceral peritoneum) or adjacent structures | CT is more useful in advanced T stages to evaluate the tumor nodularity outside |
| T4a | Tumor invades serosa (visceral peritoneum) | the stomach or invasion of the adjacent organs. |
| T4b | Tumor invades adjacent structures, such as the spleen, transverse colon, liver, diaphragm, pancreas, abdominal wall, adrenal gland, kidney, small intestine, and retroperitoneum | |
| N | ||
| NX | Regional lymph node(s) cannot be assessed | CT, PET/CT, and EUS can be used for nodal staging. Radiological criterion for nodal involvement is lymph node enlargement. |
| N0 | No regional lymph node metastasis | |
| N1 | Metastasis in 1 to 2 regional lymph nodes | |
| N2 | Metastasis in 3 to 6 regional lymph nodes | |
| N3 | Metastasis in 7 or more regional lymph nodes | |
| N3a | Metastasis in 7–15 regional lymph nodes | |
| N3b | Metastasis in 16 or more regional lymph nodes | |
| M | ||
| M0 | No distant metastasis | CT or PET/CT are recommended to assess metastatic disease. |
| M1 | Distant metastasis |
CT, computed tomography; MRI, magnetic resonance imaging; PET/CT, 18F-fluorodeoxyglucose positron emission tomography; EUS, endoscopic ultrasound.