Gastric Cancer TNM Staging
TNM Staging | AJCC 2017
The TNM staging system anatomically classifies malignancies based on the extent of the primary tumour, regional lymph node involvement, and distant metastases. Staging helps physicians decide eligibility for clinical trials, define a patient's prognosis, and determine best treatment options.
The American Joint Committee on Cancer (AJCC) publishes the AJCC Cancer Staging Manual every 6-8 years. This tool is based on the 8th edition (2017) which represents the most up to date TNM staging guide.
1. Primary Tumour (T)
* A tumour may penetrate the muscularis propria with extension into the gastrocolic or gastrohepatic ligaments, or into the greater or lesser omentum, without perforation of the visceral peritoneum covering these structures. In this case, the tumour is classified as T3. If there is perforation of the visceral peritoneum covering the gastric ligaments or the omentum, the tumour should be classified as T4.
** The adjacent structures of the stomach include the spleen, transverse colon, liver, diaphragm, pancreas, abdominal wall, adrenal gland, kidney, small intestine, and retroperitoneum.
Δ Intramural extension to the duodenum or esophagus is not considered invasion of an adjacent structure, but is classified using the depth of the greatest invasion in any of these sites.